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4 OMNR-OGS 1983 Ontario Ministry of Natural... Minister Hon - Alan w- PoPe W. T. Foster Deputy Minister ONTARIO GEOLOGICAL SURVEY Open File Report 5363 Depositional Characteristics of the Whirlpool Sandstone, Lower Silurian, Ontario by I. Peter Martini and C Salas 1983 Parts of this publication may be quoted if credit is given. It is recommended that reference to this report be made in the following form: Martini, I. Peter and Salas, C. 1983: Depositional Characteristics of the Whirlpool Sandstone, Lower Silurian, Ontario; Ontario Geological Survey Open File Report 5363, 124 p., 5 tables, numerous figures and photos.

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6 Ontario Geological Survey OPEN FILE REPORT Open file reports are made available to the public subject to the following conditions: This report is unedited. Discrepancies may occur for which the Ontario Geological Survey does not assume liability. Recommendations and statements of opinion expressed are those of the author or authors and are not to be construed as statements of government policy. Open file copies may be read at the following locations: Mines Library Ontario Ministy of Natural Resources 8th Floor, 77 Grenville Street, Toronto The office of the Regional or Resident Geologist in whose district the area covered by this report is located. Handwritten notes and sketches may be made from this report. Check with the Library or Region al or Resident Geologist's office as to whether there is a copy of this report that may be borrowed. The Library or Regional or Resident Geologist's office will also give you information on copying ar rangements. A copy of this report is available for Inter-Library Loan. This report is on file in the Regional or Resident Geologists' office(s) located at: Yonge Street Richmond Hill, Ontario L4C 3C9 The right to reproduce this report is reserved by the Ontario Ministry of Natural Resources. Permission for other reproductions must be obtained in writing from the Director, Ontario Geological Survey. E.G. Pye, Director Ontario Geological Survey ill

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8 PREFACE This study on The Depositional Characteristics of the Whirlpool Sandstone, Lower Silurian, Ontario, was initiated to provide information on the Whirlpool Sand stone, locally called the Credit Valley Sandstone, quarried in the Milton-Inglewood area of Southern Ontario and to provide concepts to aid in the exploration for, and evaluation of sandstone with good splittability. Sedimentological analysis of the Whirlpool Sandstone was undertaken to determine its depositional environment and to provide information which would assist experienced quarry operators in identifying areas having the best potential for the extraction of suitable quarry material. The results of regional sedimentology analysis show that the Limehouse-New Smithson quarry region is the best area for extracting suitable stone, and that good pros pects can be present in the Limestone-Milton region, where parts of the buried Whirlpool remains unexplored. E.G. Pye Director Ontario Geological Survey. v

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10 ACKNOWLEDGEMENTS I wish to thank the many people that helped in this study and in the preparation of this report. I like to single out Mr. M. Narain and Mr. T. Harvey of the Ministry of Natural Resources who started it all. Mr. McHarg, Mr. DeForest and Mr. Simpson provided information on their quarrying operations, and Mr. Galbraith first introduced us to the various active and abandoned quarries. Mr. J. Kwong described the petrology of selected thin section. Mr. C. Salas gathered the field information on the quarries studied in details in the Milton-Inglewood area and prepared the first version of the field report. He beneficted from discussions with Dr. Middleton and Dr. Risk of McMaster University. Mr. A. Mclellan drafted the final figures, Mrs. K. Beitz typed the manuscript. This work was financially supported by the Ontario Ministry of Natural Resources, and in part by a grant from the National Science and Engineering Research Council (NSERC Grant No. A7371). Vll

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12 ABSTRACT The Whirlpool Sandstone (Lower Silurian) has been extensively quarried as building stone in the Milton-Inglewood area, Ontario. It has been used under the trade name of "Credit Valley Sandstone" in many Government and University buildings in Southern Ontario. The economics of the industry and the depletion of the easily accessible reserves require that only shallowly (3-5 m) buried sandstone be extracted which shows good splittability ('reed' of the quarryman) and does not require sawing. The sedimentological analysis of the Whirlpool Sandstone was designed to determine the environments of deposition of this unit, but also to explain and expand the practical experience of the quarrymen to try and predict which areas have the best potential for additional extraction of suitable rocks. It was found that good reed is presented not only by plane beds, but also by large scale shallow cross-beds and swales. Sandstone with these types of sedimentary features is usually formed in large streams, coastal bars and shelf sheets. These sandstones may be locally reworked by small sand dunes or disected by channels generating medium scale, steep cross-beds (kurls) forming unworkable, waste stone. The rock with good reed may grade laterally and vertically to ripple cross-laminated ('Feathery reed' of the quarryman) sandstone which requires sawing to be used in constructions. The regional sedimentological analysis of the Whirlpool Sandstone indicates that no economic large deposit of sandstone with good reed can be found in the Milton-Hamilton area where cross-bedded intervals prevail. The best area for extracting stone is the Limehouse-New Smithson quarry region, although small kurls may interrupt the continuity of the extractable zones. Some good prospects can also be present in the Limehouse-Milton region where IX

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14 parts of the shallowly buried secondary escarpment of the Whirlpool remains unexplored. In that area however, there is the possibility of large cross- bedded channels, and a good drilling program is required for a precise evaluation. The regional sedimentological variation indicates that good rock exist in the Inglewood area as well. Other prospective areas exist, but the possibility of sawing thick intervals of ripple-cross-laminated sandstone should be considered, to eliminate much waste. XI

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16 CONTENTS Page Int roduct ion... l Objectives and justification of study... l Methods of study... 8 Results and recommendations Regional Geological Setting Stratigraphic correlations Contacts and thickness variations Lithology Colour Fossils Facies Analysis of the Milton-Inglewood area Facies Plane beds Cross-beds Large cross-beds (channels) Swale beds Ripple cross-laminations Convolute laminations Transition (Whirlpool) beds Manitoulin beds Facies associations... * Milton Quarry Brown's Farm (Barnes) Quarry Rice and McHarg Quarry Brockton Quarry New Smithson Quarry Structural Sandstone Quarry Hilltop Quarry DeForest Brothers Quarry Other features of the Whirlpool Sandstone Summary of structural characteristics Paleocurrents Engineering properties Regional slope of the Whirlpool-Queenston contact xiii

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18 Discussion Environments of deposition... * Concepts in aid to exploration of rocks with good reed Page Sedimentary structures and environments Rocks with good reed Rocks with poor reed... *... * Conclusions Exploring for rocks with good reed in the Milton-Inglewood area 120 References TABLES 1. Petrographic features of the Whirlpool Sandstone Chemical analysis of sandstone from the Milton area Statistics of directional measurements Engineering tests of quarried sandstones Approximate elevation of the Queenston-Whirlpool contact FIGURES 1. Regional stratigraphic correlation Major sections of the Lower Silurian along the Niagara Escarpment... * Location of quarries studied in the Milton-Inglewood area Lithofacies variation along the Niagara Escarpment Structural basins of northeastern America and Lower Silurian units in the Appalachian Basin Distribution of the Whirlpool Sandstone in Ontario Petrographic characteristics Secondary sedimentary features... * Field of stability of primary sedimentary structures Primary sedimentary features formed under shooting flow conditions Primary sedimentary features of the Whirlpool formed under shooting flow conditions... * Types of cross-beds Cross-beds of the Whirlpool xv

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20 Page 14. Cross-beds of the Whirlpool Cross-beds of the Whirlpool Shallow dipping cross-beds and swales Ripple marks diagrams Ripple marks of the Whirlpool Ripple marks of the Whirlpool Various sedimentary structures of the Whirlpool Stratigraphic section of the Milton Quarry Stratigraphic sections of the Brown's Farm (Barnes) Quarry Faces of the Brown's Farm and Rice and McHarg Quarries Stratigraphic section of the Rice and McHarg Quarry Map of the sedimentary features observed on the floor of the Rice and McHarg Quarry Cross-sections of the Rice and McHarg Quarry Fracture pattern in the Rice and McHarg Quarry Stratigraphic section of the Brockton Quarry...* Stratigraphic section of the New Smithson Quarry Stratigraphic section of the Structural Sandstone Quarry Stratigraphic section of the Hilltop Quarry Stratigraphic section of the DeForest Brothers Quarry Features of the Whirlpool Sandstone at Rochester (N.Y.) and Lockport (N.Y.) Features of the Whirlpool Sandstone at Niagara Gorge, De Cew Falls and Hamilton Stratigraphic cross-section of the Milton-Inglewood area Paleocurrent directions along the Niagara Escarpment Environmental model of the Whirlpool Sandstone xvii

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22 Depositional Characteristics of the Whirlpool Sandstone, Lower Silurian, Ontario l 2 by I. Peter Martini and C. Salas Department of Land Resource Science, University of Gueplh, Guelph, Ontario NIG 2W1 2 Department of Geology, McMaster University, Hamilton, Ontario Manuscript approved by C.R. Kustra, Regional Liason Geologist, February 28, This report is published with the permission of E.G. Pye, Director, Ontario Geological Survey. xix

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24 INTRODUCTION OBJECTIVES AND JUSTIFICATION OF THE STUDY The objectives of this report are: 1. To review existing information and interpretations on the environment of deposition of the Whirlpool Sandstone (Lower Silurian) exposed along the Niagara Escarpment in Western New York and Ontario (Figs, l, 2). 2. To provide new detailed information about the Whirlpool Sandstone mined in the Milton-Inglewood area, and locally known as "the Credit Valley Sandstone" (Fig. 3). 3. To provide a few basic concepts in aid to exploration for, and evaluation of the sandstone with good splittability (with good "reed") in the Milton-Inglewood region. Utilizing a preliminary environmental model, areas are indicated where remaining good reserve of accessible workable sandstone may be present. The study has been prompted by several concomitant factors. 1. The industry of extracting sandstone for building purposes has been under economic stress since the sixties. The reducing amount of good, readily accessible sandstone, combined with the market competition provided by less expensive artificially generated products, has prompted the closure of many quarries. At present only three permanently open quarries extract building stones from the Lower Silurian sandstone. They are all located in the Milton-Inglewood area. 2. The existent quarries are profitable small scale enterprises. To remain competitive they need to be able to work on rocks with good splitting properties to avoid costly sawing operations. Therefore good "reed" sandstones are required and they must be available at shallow depths

25 - 2 - Figure 1. Regional correlation of the Lower and Middle Silurian along the Niagara Escarpment (after Chaivre and Sanford, 1972). Insert shows correlative units toward the Appalachians Mountains (after Pettijohn et al., 1972).

26 Medina l ALLUVIAL -,... Conglomeratic facies TRANSITION ZONE TIME LINES Conformable CONTACTS Concordant Discordant MARINE ROUTE 20 AT STONEY CREEK (SC) NIAGARA AREA (R) ROCHESTER AREA (G) 7*5*. *X h \ \ 'NT \ uiiniaurnu l Jl ) WILLIAMSON ^ SODUS 'Q N N O N

27 - 4 - Figure 2. Location of major outcrops and stratigraphic sections of the Lower Silurian Medina Group along the Niagara Escarpment (after Martini, 1974).

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29 Figure 3. Location of quarries studied in the Milton-Inglewood area.

30 WHIRLPOOL SANDSTONE QUARRIES Milton - Inglewood 1. Milton (Barnes) 2. Brockton 3. Brown 's Farm (Barnes) 4. Rice St McHarg New.Smithson 6. Structural Sandstone 7. Hilltop 8. De Forest

31 (less than 3-5 m overburden). The area between Milton and Inglewood is a favoured location for the extraction of the Whirlpool Sandstone where it forms a lower secondary scarp. 3. Basic information on the sandstone resource is urgently required for the Milton-Inglewood area to foster and support sensible conservation and development policies, particularly at a time when the new Niagara Escarpment conservation plan is pending. 4. Geologically, renewed interest has been generated for the study of the Whirlpool and other similar thin basal quartzose sandstones which contain numerous cross-beds, and are generally poorly explained. Whereas the existing interpretations suggest ill defined transgressive, shallow marine environment of deposition, new sedimentological concepts suggest that perhaps these types of rocks may, in part, be of fluvial origin, particularly of braided streams. Such conditions would fit well with subtropical Lower Silurian landscapes, which were not protected by higher land plants, as they had not yet been evolved at the time. STUDY DESIGN AND METHODS This study was designed as a pilot analysis of the best exposures of the Credit Valley Sandstone (Whirlpool Sandstone, Lower Silurian) in the Milton-Inglewood area to assess which rock types (lithofacies) are more suitable for flagstone extraction. The sequences of the Milton-Inglewood area were also compared and contrasted with those of the best exposures along the Niagara Escarpment in Southwestern Ontario and Northeastern New York to determine the regional variation of the characteristics (facies) of the Whirlpool Sandstone. This is a necessary step in the reserch for better understanding of the paleoenvironments of deposition of these rocks, thus of the distribution of specific lithofacies suitable for mining.

32 - 9 - The study consisted of the following steps. 1. A review was made of the most up-to-date literature pertaining to the Whirlpool Sandstone. 2. Whereas the outcrops of the southermost part of the Niagara Peninsula and adjacent New York state are well known and needed only a cursory reexamination (Martini, 1966; Friedman et al. 1982), the quarries from Milton to Inglewood were examined accurately during several exploratory visits. 3. Eight quarries were selected for detailed analysis. The selection was designed to include all the working quarries, and complementary representative exposures from Milton to Inglewood. 4. The Rice and McHarg quarry was chosen for further detailed study because it has been and still is being worked on for considerable length of time, and it has good exposures of rocks along the walls and on the floor. In this quarry the three dimensional characteristics of the different types of rocks (lithofacies) can be readily observed. Other quarries have similar exposures, such as the Hazel Norrie quarries. They shall need further study. 5. The first step in the analysis of the exposures was to try and identify the reoccuring lithofacies, that is those rock units which are uniquely characterized by an assemblage of textures (grain size), color, sedimentary structures, and fossils. 6. Where large exposures occur, several vertical sections were measured on different walls of the quarries. A representative vertical section or a composite one, where scattered outcrop occur or where strong variation exists, are reported for each quarry. 7. The 'facies thickness 1 was determined as an arbitrary, semi-quantitative estimate of the relative abundance (thickness) of the different facies,

33 in respect to the sum of the thicknesses of the various facies measured in the sections of the quarries. 8. The sedimentary features exposed on the walls and on the floor of the Rice and McHarg quarry were mapped in details after positioning them on the basis of a detailed topographic survey. Standard techniques are used in the measurements, descriptions and sampling of the sections (Kottlowski, 1965). 1. Rock grain size was estimated in the field using a comparator chart, and is reported either in millimeters or in phi (4* * ~log 2 nrm) (Folk, 1961). The major subdivisions of grain size classes are: mm phi(({)) pebble ^ very coarse sand ; O coarse sand ; -fi medium sand ; 2 fine sand ; 3 very fine sand ; 4 silt ; 8 clay ^.0039 ^ 2. The colour of the rocks was determined in the field utilizing the Munsell rock colour chart. 3. Paleocurrent direction was determined by measuring the azimuths of maximum slopes of cross beds, cross-laminations, and the directions indicated by current crescents, parting lineations and preferred orientation of fossils. The orientation of ripple crests and the long axes of pebbles provide directions perpendicular to the paleocurrent.

34 The paleocurrent data obtained during this study and from previous ones were analyzed utilizing a modified computer program (after Martini, 1965). It provides the average paleocurrent direction, a measure of dispersion of the data around such an average, and a test (Tukey X 2 ) on whether the distributions show preferred orientations* 5. The paleocurrent distributions are reported in rose diagrams. The rose diagrams of vectorial data (cross-beds, cross-laminations, current crescents) have 40 0 classes. The paleocurrent data showing paleocurrent trends, but not direction of flow (parting lineations, ripple crests and pebble a-axis orientations) were subjected to a 29 transformation (the measured angle was doubled), and the rose diagrams were constructed with 20 0 classes, each being repeated in the opposite quadrats in a mirrorlike fashion. 6. Oriented samples were collected from each lithofacies (facies) from each quarry. Several thin sections were cut perpendicular to bedding to determine the petrography of the rocks. ' 7. A qualitative petrographic description is provided for representative thin sections. The quantitative determination of the relative abundance of the different minerals and other components of the rock are reported as percentage of approximately 300 point counts for each thin section. RESULTS OF THE STUDY AND RECCOMENDATIONS FOR FUTURE WORK This study was conducted during the second half of It is based on published data, available unpublished data, and new data obtained during a two months field season in the Milton-Inglewood area. The study has beneficted by the opinion of several leading sedimentologists who have visited the outcrops along the Niagara Escarpments and in the Milton-

35 Inglewood area, prior to or after the International Congress of Sedimentology held in Hamilton in August, The main results of this study include: 1. Definition of the principal lithofacies of the Whirlpool Sandstone. 2. Identification and analysis of these facies suitable for flagstone mining. 3. Detailed description of the sequences (facies associations) present in the main outcrops and quarries of the Whirlpool. 4. Reconstruction of the paleoenvironments of sedimentation of the Whirlpool Sandstone. Such a preliminary model serves to explain the occurrence of certain types of rocks at various localities and provides bases for prediction of workable stones in areas still to be exploited. Future research on the Whirlpool Sandstone should focus on: 1. Other quarries in the Milton-Inglewood area provide three dimentional exposures of the Whirlpool, thus the anatomy of its sedimentation could be clearly understood. The Hazel M. Norris quarries (Lot l, Concession 3, Caledon; and Lot 30, Concession 6, Chinguacousy) provide perhaps some of the largest exposures still to be analyzed in details. 2. The petrographic analysis of the Whirlpool should be extended. Particular effort should be placed in the analysis of the cementing materials and the pyritic mineralizations which occur in the lowermost beds of the units, and in minor measure, at other different horizons. 3. The surface information needs to be extrapolated into the subsurface, a. Firstly, a coring program should be implemented in the Milton- Inlgewood area where the sandstone can be found at shallow depth. This would serve both for testing locally in the Limehouse area the environmental model proposed, and in evaluating possible future quarrying prospects in the Milton-Limehouse area.

36 b. Secondly, a regional subsurface study should be conducted utilizing available cores, cuttings and mechanical logs of wells drilled for the hydrocarbon exploration. Such a study is required to determine the paleogeography and environments of deposition of the Whirlpool Sandstone. This could in turn provide new information on the subsurface reservoir and traps for hydrocarbons. REGIONAL GEOLOGICAL SETTING STRATIGRAPHIC CORRELATIONS The regional development of the Upper Ordovician and Lower Silurian of Western New York and Southern Ontario is related to the evolution of the Taconic (Appalachian) Mountains (Sanford, 1972). East-west cross sections either along the Niagara Escarpment or in the subsurface show consistent thinning westward of the clastic wedges shed from the rising taconic Mountains (Fig. 1). The Algonquin arch of the Southwestern Ontario penisula separated the Appalachian basin to the east from the intracratonic Michigan basin to the west (Fig. 4), where carbonate deposition prevailed. Stratigraphically, the Ordovician Queenston Formation is correlated with the Juniata and Bald Eagle Formations of the Pennsylvania, Ohio areas (Fisher, 1954, 1966). The Lower Silurian Medina Group is generally correlated with the Tuscarora and Shawangunk Formations (Fisher, 1960; Berry and Boucot, 1970; Sanford, 1972). The Medina is considered to have been derived from the erosion and redistribution of the red Ordovician deposits of the Appalachian Regions (Fisher, 1954, Martini, 1971). The Taconic clastic wedge grew through repetitive development of large deltas, alternating with major marine transgressions (Yeakel, 1962). In western New York and Ontario a major widespread emersion occurred at the

37 Figure 4. Major lithofacies variations of the Lower and Middle Silurian along the Niagara Escarpment. 1. Medina; 2. Niagara Falls; 3. Hamilton; 4. Cataract; 5. Owen Sound; 6. Cabot Head; 7. Manitoulin Island; 8. Mastinique.

38 i i ~ r ' i i ' T i it CABOTJHEAD 150 J 15

39 end of the Queenston deposition. Such a well defined raudcracked surface Is sharply overlain by the well sorted gray sandstone of the Lower Silurian Whirlpool Sandstone. During the deposition of the Whirlpool a major transgression occurred in the region with the injection of the sublittoral shales of the Cabot Head and the dolostones of the Manitoulin as far east as the Niagara River and Lockport (Martini, 1966, 1971, 1974; Friedman, et al., 1982). Subsequently, a reactivation of the deltaic conditions lead to a regression and the deposition of the Grimsby Sandstone. repeated during the lower part of the Middle Silurian. A similar cycle That transgressive phase is marked by the Thorold Sandstone and the overlying Clinton carbonates. The renewed pulse of clastic input in the basin is recorded by the marine Rochester shales which thin from the Niagara Region to the west (Fig. 1). Some difficulty has always been encountered in dealing with the Whirlpool Sandstone. The Whirlpool Sandstone (Lower Silurian) was first named officially by Grabau (1909). He assigned that name to the white quartzose sandstone that occurs at the base of the Medina Group. Previously the rock formation was popularly referred to as the White Medina. Grabau (1913) considered the Whilrpool to be a local facies not directly connected to any particular eastern source. Fisher (1954) suggested that the Oswego Sandstone or similar Appalachian origin is the direct source of the Whirlpool. More recently the Whirlpool Sandstone has been interpreted as being a tongue attached to the coarse 'Clinton 1 to the east (Heyman, 1977; quoted by Seyler, 1981), or an "anomalous finger" (of the Tuscarora Formation) possessing a different source than the other units of the Medina Group (Knight, 1969).

40 The Whirlpool Sandstone is mineralogically mature and undoubtly of second cycle (Alling, 1936). Only the more stable heavy minerals are present indicating that wind and water were jointly responsible for the transportation of the constituent grains from their source to the present sites of deposition (Holstein, 1936, p. 56). Furthermore, the restricted heavy mineral suites indicate that they are not typical of Precambrian distributive provinces (Holstein, 1936). Therefore combining the westward thinning of the formation, increased sorting and a decrese in grain size, and the prevalent paleocurrent direction, all substantiate the fact that the Whirlpool Sandstone has an Appalachian Origin. Van Tyne (1979; quoted by Seyler, 1981) shows an eastern pinch out of the Whirlpool and the associated marine Power Glen (Bolton, 1957) in New York, and a thickening toward the Great Lakes. Similarly, Yeakel (1962) showed the boundary between the continental facies of the Tuscarora and the marine facies of the Lower Silurian rocks to the west in the Great Lakes Region. Such a boundary approximately delimits the hydrocarbon producing trend of the Medina (Fig. 5; Martini, 1971). The Whirlpool pinches out along the Niagara Escarpment between Medina and Rochester, and north of Beaver Valley (Fisher, 1954; Martini, 1966; Telford, 1973). The typical gray quartzose to fedspatic sandstone facies is limited to the westernmost part of New York, Lake Erie and the southern Ontario peninsula east of the Algonquin Arch (Fig. 6). CONTACTS AND THICKNESS VARIATION The type section of the Whirlpool Sandstone is at the omonimous location in the Niagara Gorge, where it is 5.5 m (M8 ft) thick (the upper contact with the Cabot Head (Fisher Creek; Fisher, 1954) is not exposed). The formation outcrops along the Niagara Escarpment from Medina (New York)

41 Figure 5. Structural basins of central-east America, and distribution of lower Silurian units in the Appalachian Basin.

42 ' ' -' - ' ' "' ' '-~C^'- -ILLINOIS. A i: C - ' ' '-ilx^-o^ ' ' "' ' ' - ' ' -\ 0 ^ '^^' /^ztr^v'-'.-.'ba-s'ln-'.'-'.-j Cretaceous and Tertiary l l Early Paleozoic IH Late Paleozoic J Crystalline 19

43 Figure 6. Distribution of the Whirlpool Sandstone in Ontario (after Sanford, 1969).

44 LAKE HURON MANITOULIN DOLOSTONE WHIRLPOOL SANDSTONE CABOT HEAD SHALE 80 21

45 to the Beaver Valley at Duncan, approximately 12.2 km (8 miles) south of Collingwood. East of Medina in the Holley-Rochester region (N.Y.), the typical light gray Whirlpool Sandstone is laterally replaced by a thick (2.4 m (8 ft)), coarse, undulating to finely laminated, red sandstone unit which marks the base of the Medina along a sharp, flat contact with the underlying shales and sandstones of the red Queenston (Ordovician). North of the Beaver Valley the Whirlpool is replaced by shales and the carbonate units typical of the Michigan Basin (Fig. 4). In the subsurface, the Whirlpool thins out considerably from the central New York region where 34 m (112 ft) of the White Medina have been reported in the Chemung County, to the average thickness of 6.1 (20 ft) in northeastern New York State and Ontario. Along the Niagara Escarpment in Ontario, the Whirlpool thins out regionally from a maximum of 8.5 m (28 ft) in the Niagara Gorge to a minimum of 2.4 m (8 ft) at Webster Falls in the Hamilton region (Bolton, 1957). Local variations in thickness have been reported both in outcrops and boreholes. Whereas some variations may be associated to uneven topography at the surface of the Queenston contact, some variations may be related to the fact that the upper contact of the formation is gradational with the shales of the Cabot Head or the silty argillaceous dolostone of the Manitoulin, and it is difficult to be identified objectively. This upper contact is generally taken to be at an ill specified top of the last massive sandstone unit (Bolton, 1957) or at the bottom of the first dolostone bed above the sandy interval. In the Milton-Inglewood area a convenient marker is provided by a calcarenite layer which has well developed large vugs partially filled with calcite crystals. The lower contact of the Whirlpool with the Queenston, is consistently sharp and mud-cracked.

46 LITHOLOGY The Whirlpool is typically a medium to thick bedded, very light gray (N8) fine to coarse grained, well sorted unfossiliferous sandstone. Alling (1936) classified the Whirlpool of the Niagara section as a feldspatic sandstone having quartz as the dominant species, and microcline, plagioclase, garnet, leucoxene, magnetite, apatite, and zircon as accessories. Seyler (1981) confirmed that the Whirlpool Sandstone is a subarkose (Dott, 1964) in the Niagara area. Petrographic analyses of the sandstone in the Milton-Inglewood area indicate that the highly quartzose sandstone can be classified as a subarkose (feldspatic sandstone) (Table 1; Pettijohn et al., 1972). Parks (1912) reported that the sandstone mined in the Orangeville area is gray, fine grained, quartzose with few heavy weathered feldspar grains. This sandstone has a calcite cement and some argillaceous matter (Table l, Fig. 7). Preliminary observations suggest that whereas the Whirlpool of the Niagara-Hamilton region is tightly cemented primarily by quartz, other outcrops along the Niagara Escarpment farther to the west in New York and farther to the North in Ontario have still quartz cement, but also an increasing amount of calcite cement (Fig. 7). The variation of cement types and amounts differentiate the tight hard sandstone of the Hamilton-Niagara region from the more porous and less resistant sandstone of the Milton-Inglewood area. Mineralizations of Cu and Fe bearing minerals, primarily pyrite and chalcopyrite occur in thin laminae and small concretions all along the outcrop belt, and are particularly common in the Milton-Inglewood area (Fig. 8A). Locally in the lowermost layers, a heavy mineralization of the sandstone occur and pyritic cement prevails in some basal beds (Table 1). Seyler (1982) reports abundant hematite from the Niagara Gorge area.

47 The Whirlpool has a relatively consistent suite of heavy minerals, of the most resistant species. Holstein (1936) however, succeded in subdividing the formation into a lower unit characterized by a heavy mineral assemblage dominated by zircon, and an upper unit dominated by collophane (Fig. 7). The grain size of the Whirlpool Sandstone shows a regional fining along the Niagara Escarpment from the east to the west and north, with coarse sand in New York and fine sand in the Hamilton-Inglewood area. Clay pebbles are reworked into sandstone beds of the lower and middle part of the formation (Fig. 8B). No clay drapes however, have been observed in the lower two-thirds of the formation. Thin clay interlayers occur in the top part of the formation. Vertically, the largest grain size is usually found in the middle part of the Whirlpool Sandstone (85% sand, 9% silt, 6% clay: Lockwood, 1942), with an occasional fining toward the base (61Z sand, 28% silt, H.% clay: Lockwood, 1942), and a consistent fining toward the top (49% sand, 37Z silt, 14X clay: Lockwood, 1942; Geitz, 1952). Well rounded and frosted sand grains are locally common, particularly in the lower few centimeters of the formation (Fisher, 1954). Regionally, the average size of quartz grains decreases from 0.26 mm near Niagara Falls to 0.18 mm at Hamilton, to mm at Duntroon (Winder, 1968; Koepke, 1960). COLOUR Variations occur in the colouration of the formation. Red mottled zones have been reported from boreholes in the Niagara Region (Bolton, 1957). Along the outcrops, the Whirlpool is characteristically a gray to buff gray sandstone unit, except to the west of Medina (NY) and in thick lower portions of the unit in local quarries in the Limehouse-Inglewood area

48 (New Smithson and DeForest quarries (Fig. 3)) where dark red to brown red colours occur (Hewitt, 1952; Parks, 1912). FOSSILS The lower 2/3 of the Whirlpool Sandstone is unfossiliferous, except for scattered continental algal spores (Miller and Eames, 1982; Strother and Traverse, 1979). They are found preferentially in the lowermost layer. Rare ooid structure are present. Seyler (1981) reports phosphatized ostracods in the Niagara region. 'Problematic traks* have been observed at the mudcracked contact with the Queenston and in the lower beds of the Whirlpool in the Limehouse-Inglewood area. Abundant problematic burrows have been reported by Seyler (1981) from the lowermost 30 cm of the Whirlpool in the Niagara Gorge. The upper 1/3 of the formation has abundant trace fossils. Locally the primary sedimentary structures are heavily disturbed or completely obliterated by bioturbation. This fossiliferous zone characterizes the marine transition of the Whirlpool either to the overlying open marine shales of the Cabot Head (Power Glen (Bolton, 1957), Fisher Creek (Fisher, 1954)) in the De Cew Fall-Lockport area, or to the Manitoulin Dolostone in the Hamilton-Inglewood area.

49 Figure 7. Petrographic characteristics of the Whirlpool Sandstone in the Milton-Inglewood area. A. Typical gray sandstone of the lower Whirlpool (q quartz grain; s - quartz overgrowth), B. sandstone of the upper beds of Whirlpool (c - calcite cement, y - pyrite) C,D,E,F sandstone of the lowermost bed of the Whirlpool Sandstone (o 3 ooidal structure, p collophane pellets(?), r " spores)

50

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53 Figure 8. Sedimentary features of the Whirlpool Sandstone. A. Mineraliza tion along a bedding surface, B. Clay pebbles (Rice and McHarg Quarry), C. Mudcracks in the upper Whirlpool (Brown's farm Quarry), D. Mudcracs and other traces at the bottom of the Whirlpool (Hilltom Quarry).

54

55 FACIES ANALYSIS OF THE MILTON-INGLEWOOD AREA FACIES The Whirlpool Sandstone In the Milton-Inglewood area is characterized by eight major lithofacies: Plane beds (A), Swale beds (B), Cross-beds (C), Large troughs (D), Ripple cross-laminations (E), Convolute laminations (F), Transition (Whirlpool) beds (G), and Manitoulin beds (H, M). PLANE BEDS (A) Plane beds are one of the primary sedimentary structures formed under specific flow conditions (Fig. 9). They commonly parallel horizontal bedding plane (Figs. 10B, 11A), but they can also develop on wavy and inclined depositional surfaces (Figs. 10, 11D). Plane beds are found at all locations studied and generally make up 272^ of the measured "facies thickness", up to 59Z at the Rice and McHarg quarry. The plane beds are characterized by internal parallel laminae ranging in thickness from 0.5 to 4 mm (av. l mm). Heavy mineral concentrations along some surfaces provide convinient dark colouration which allows easy recognition of the laminae, except in the more deeply red coloured rocks. The laminae are laterally extensive. The plane beds range in thickness from 4 to 40 cm with an average of 14 cm. Generally they show good splittability (A 2 )- They are seldom ill defined (A x ) and difficult to split. The bedding surfaces of these beds invariably show parting lineations (PL) (Crowell, 1959; Allen 1982, p. 260), parting-step lineations (PSL) (McBride and Yeakel, 1963), and a variety of other current lineations (Fig. 10B). Among these, a characteristic accumulation of heavy minerals

56 flaring downstream is good indicator of "trend" as well as "vectorial direction" of the paleocurrents (Fig. 11B; R.J. Cheel, pers. comm.). Other directional information is obtained from current crescents formed around clay pebbles (Fig* 11C). Locally the clay pebbles are abundant and are oriented perpendicularly to the paleocurrent direction (Fig. 36). This facies is constituted of a mature quartz sandstone uniformly cemented primarily by quartz and calcite. The grain size ranges from 2.0 to 3.50 with average around Sorting is good and the grains are subrounded. The colour of the rock is generally light yellowish gray (5Y 8/2). However, a reddish-purple (5R 5/2) variety of this facies is found in significant amount at two localities (New Smithson and DeForest Quarries) (Fig. 3). Generally this red sub-facies is finer than the norm (average 3.50), its parallel laminations are more difficult to discern. Mineralization by iron and copper is common along hte surface of laminae. It is very thin (few mm), but laterally extensive (order of meters) and locally it forms pseudo-concretions a few millimeters thick and few centimeters wide (Fig. 8A). CROSS-BEDS (C) This facies comprises primarily trough cross-beds (0^,02? Figs. 12, 13), rare tabular cross-beds (Co; Fig. 12) and occasional sigmoidal units (Fig. 14A). The trough cross-beds can be further subdivided into units with steep (C 2) foresets ( ; Fig. 14), and units with shallow (Cj) foreset dips ( ; Figs. 15C, E; 16A, B, C, D). The second type has usually plane laminated foresets with good splittability ("reed"). The trough cross-beds are widely distributed and are found at all but two of the

57 Figure 9. Fields of stability of primary sedimentary structures (after Allen, 1968, 1982).

58 40 10 UP AD 4 UP LP.D UP CN 'E 0.1 lo NM B J I I I l l I I I d AD Antidunes UP Upperstage Plane Bed D Dunes R Current Ripples LP Lower Stage Plane Bed NM No Movement d Grain Size (mm) w Stream Power V. FINE COARSE V COARSE } Sand Grade 35

59 - 36- Figure 10. Primary sedimentary structures. A. Various stages of flow and sandwaves (antidunes) under shooting flow conditions (after Allen, 1982), B. Plane beds with parting and parting-step lineations, C. Hummocky Cross-Stratification, D. Swash marks and beach cross-lamination (after Harms and al., 1982).

60 Flow Flow ^ilwuhli x^'pppi^s^sssess B 2-100

61 Figure 11. Sedimentary features of the Whirlpool Sandstone. A. Plane beds (Brown's farm), B. Parting lineations and heavy mineral flares (Rice and McHarg Quarry), C. Current crescents (Hilltop Quarry), D. Undulating plane beds resembling Hummocky Cross Stratifications (New Smithson Quarry).

62

63 B (b) KEY Lone-* ale ovo'oncr-.1 bedding Cross-bedding Cross- lamination Mud drapes [y^g&j Mud closts 41

64 Figure 13. Cross-beds of the Whirlpool Sandstone. A. Trough cross-beds seen on a bedding surface, B. Shallow, large cross-bed seen both on the bedding surface and on a vertical section, C. Exumed slipface, D. Large scale-trough cross-bed seen on a bedding plane, E. Coset of cross-beds in a vertical face. Photographs A to D are from Rice and McHarg Quarry, E. is from De Cew Falls.

65

66 Figure 14. Cross-beds of the Whirlpool Sandstone. A. Sigmoidal cross-bed (Hilton Quarry), B. Large trough (channel) (Brown's Farm Quarry), C. Trough cross-bedded zone (Brown's Farm Quarry), D. Trough cross-bed (Rice and McHarg Quarry).

67

68 quarries studied (New Smithson and DeForest quarries), and make up T.7% of the measured facies thickness. The geometry and scale of the cross-beds vary considerably within and between quarries. In general, the single isolated sets are most common (Fig. ISA), but cosets of up to four sets are widespread (Figs. 13E, 14D). Single sets range in thickness between 50 and 100 cm with average of 60 cm, and cosets up to 200 cm thick are found in the Milton quarry. Where good exposures of the bedding surfaces as well as the vertical cuts are available, such as at the Rice and McHarg quarry, thin (approximately 30 cm), wide (approximately 5 cm) cross-beds with shallowly dipping (15 0 ) foresets are observed (Figs. 13; 15C, E; 16A, B, C). Generally the foreset thicknesses range from 0.5 to 6 cm. The visible geometry of the cross-beds varies depending on the orientation of the outcrops in response to the paleocurrent direction. In most cases the sets are wedge shaped generally with tangential lower contacts, and they extend laterally for 2 to more than 20 m. Strait crested, tabular cross-beds exposed in outcrops perpendicularly to the paleocurrent direction, resemble and can be mistaken for plane beds (Figs. 12; 15D). The lithology of the cross-beds does not differ generally from that of the other facies within the same quarry, except for the troughs at the base of the Whirlpool. There, a fining upward sequence occurs varying in size from 1.5 to Sorting is generally good. The grains are subrounded. Locally, shale pebbles are heavily concentrated toward the toe of the foresets where they can generate sandy, clay pebble conglomerates. Mineralization is not widespread except in the 30 cm of the Whirlpool where pyrite is present as cement and replacement of phosphatic grains.

69 LARGE CROSS-BEDS (CHANNELS) (D) This large cross-beds facies is present only in the Brown 1 s Farm (Barnes) and Structural Sandstone Quarries. It makes up 12'K of the measured facies thickness. The large cross-beds occur as single trough features, filling channels locally defined by exposed cutbanks (Fig. 14B). The channels range in size up to 2.4 m in depth and more than 25 m in width along the outrop. The inclined beds of the troughs range in thickness from 0.5 cm to 'apparent* 40 cm where they are not well weathered out. They all show either plane laminations or well developed ripple marks. In some troughs the ripple cross-laminations record reverse flow, climbing upslope on the foresets (Fig. 12D). The sand of this facies is on the average coarser than that of other facies, averaging Locally high concentrations of clay pebbles occur along the foresets and particularly toward the deeper central parts of the troughs. SWALE BEDS (B) The swale beds facies is found in its typical form at the DeForest quarry (Figs. 3; 16D). The swale beds are characterized by undulating surfaces having large wavelength (20 m) and small amplitude (maximum 21 m). The slope of the beds is generally six degrees. However, in one instance the beds grade into a steeply inclined (24 0 ), wide surface of unknown origin, possibly of a large bar-beach landform. The individual beds making up the swales range in thickness from 10 to 30 cm with average of 15 cm. The swale beds persist for 2.6 m of the exposed section of the DeForest quarry. This interval can be subdivided

70 Figure 15. Cross-beds. A. Single trough cross-bed set (Brockton Quarry), B. Cross-bed apparently reversing paleocurrent, C. Shallow dipping cross-bed, D. Cross-beds showing apparent plane beds in section perpendicular to flow, E. Shallow dipping trough crossbed. Photographs B to E are from Rice and McHarg.

71

72 Figure 16. Shallow dipping cross-beds or swales. A, B, C general views and details from Rice and McHarg, D. Large shallow swales from DeForest Quarry.

73

74 into a lower reddish (5R 5/2) plane laminated subfacies and an upper light yellowish gray (5Y 8/1) ripple marked upper subfacies. The lower subfacies presents good splittability along the sides of the swales, loosing it somewhat toward the center of the trough* The grain size of this facies is uniform ranging from 2.0 to It shows good sorting and subrounded grains. RIPPLE CROSS-LAMINATIONS (E) Ripple marks develop in a variety of forms under specific conditions of flow and grain size (Figs. 9, 17). The ripple cross-laminations occur in every quarry studied, and they comprise 14.5% of the measured facies thickness. Trough (E j) cross- laminations are most common and they are formed by various ripple marks. The wave (E 2 ) ripples are present, but they are restricted to the upper part (1/3) of the Whirlpool. Although an intense search for them was made in outcrop east of Hamilton by Fisher (1954) none was found in the lower part (2/3) of the Whirlpool Sandstone. A variety of ripple marks is recognizable on well exposed bedding planes, primarily of linguoid and, secondarily, of lunate, straight crested, and symmetrical forms (Figs. 18, 19). The small troughs show on the bedding surface as characteristic rib and furrow structures (Fig. 19B, D, E). Well developed ripple-fans are present (Fig. 18D). The ripple indices average 6 cm and range between 2.4 and 10. The dip of the cross-laminae is about 6 0. The layers containing trough ripple cross-laminations are generally thin to medium bedded. Mineralization is seldom present.

75 The wave ripples are best developed at the base of the transition zone, in the upper 1/3 of the Whirlpool, in thin (7-30 cm) beds (Figs. 20A, B). The wave ripples are straight to slightly sinuous, rarely bifurcating, with rounded to sharp crests. Internally, the cross-laminae show a preferred direction of transport. Interference ripples are present as well. The ripple index varies from 6 to 15 with modes at 6 and 12. The Hilltop quarry exposes one of the best and thickest sequence of the ripple cross-lamination facies. CONVOLUTE LAMINATIONS (F) The convolute lamination facies is rare, making up only Q.6% of the measured facies thickness. This facies is restricted to silty sand beds and represent penecontemporaneous deformation of pre-existent ripples by escaping water during compaction (Fig. 20C). It is typically represented in few thin interlayers in the Milton quarry in association with thick ripple cross-lamination facies. TRANSITION (WHIRLPOOL) BEDS (G) The Whirlpool Sandstone has a gradational upper contact with the Manitoulin Dolostone. Invariably this transition zone is marked by thin shale (I) beds alternating with thin fossiliferous (primarily trace fossils) fine to very fine sandstone layers, ranging in thickness between 3 to 17 cm. These transition beds are arbitrarily assigned to the Whirlpool Sandstone, and are considered to represent the clearly marine facies of this unit. Two sub-facies can be distinguished in the transition beds. One (GI) is characterized by a variety of ripple marks including wave,

76 Figure 17. Ripple marks. A. Classification of small scale and large scale ripple forms (after Allen, 1968), B. Regular ripple marks and ripple cross-laminations, C. Three dimensional linguoid ripple marks and trough ripple cross-laminations, D. Ripple marks with a variable angle of drift shown in a section parallel to the flow (after Harms et al., 1982).

77 55 r Ul Depth decreoses m Velocity increases r Straight Sinuous l l Symmetric Asymmetric Linguoid Depth Velocity decreases increases B

78 Figure 18. Ripple marks as seen in the quarry floor of Rice and McHarg Quarry. A. Wave ripples, B. Straight ripples, C. Ripple fan and exumed slipface, D. Ripple fan.

79

80 Figure 19. Ripple marks. A. Rippled bed, B. Plane and vertical views of ripple marks (Hilltop Quarry), C. Ripple cross-laminations (Hilltop Quarry), E,F,G. Different views of rippled bed (parallel to the bedding surface (E), perpendicular to paleocurrent (F), and parallel to paleocurrent (G)) (After Allen, 1982).

81

82 Figure 20. A. Wave ripple marks (Brockton Quarry), B. Storm layers and wave ripple marks (New Smithson Quarry), C. Convolute laminations (Milton Quarry), D. Plane bedded storm layers and bioturbation (Hamilton).

83

84 interference and straight crested ripples, and occasional plane bedded storm layers (Fig. 2QB). Biturbation (trails and burfows) are common (Fig. 20D). This sub-facies is the most common one and represent 7.1Z of the measured facies thickness. The second sub-facies (G 2 ) is well developed only at the New Smithson quarry, and makes up 2% of the measured facies thickness. This sub-facies is characterized primarily by lensing beds, showing internal wavy plane beds, resembling in two dimensional view the Hummocky Cross- Stratifications of Harms et al. (1982) (Fig. 11D). Those beds have a sharp base, and have some clay pebbles. They are storm deposits. The intervening gray shales contain some brocken bryozoa fragments and burrows. MANITOULIN BEDS (H, M) The lower beds (H) of the Manitoulin are made up of thinly bedded (10 cm) bioturbated calcareous siltstone to silty bioclastic dolostone. Internal stratifications are rarely preserved because of intense bioturbation. The lower contact is generally marked by a very dense dolomitlzed calcarenite bed containing large vugs (up to 8 cm in diameter). In other instances, the lower contact is gradatlonal into the transitional Whirlpool layers. The lower beds of the Manitoulin (H) form approximately 132 of the measured facies. They grade imperceptibly upward into the main body (M) of the Manitoulin Formation which is characterized by a bioclastic argillaceous dolostone alternating with thin shale beds and partings. Throughout the Manitoulin sequence there is a variety of fragments of crinoid ossicles, rugose corals, bryozoa and trace fossils.

85 FACIES ASSOCIATIONS MILTON QUARRY (Barnes) (Lot 18, Concenssion 6, Milton) This is the southernmost quarry studied in details in the Milton- Inglewood area (Figs. 3, 21). The whole Whirlpool unit is exposed. Its sequence resembles more to those exposed in the Hamilton and Niagara Peninsula, rather than those of the Limehouse-Inglewood area. The quarry has large wall exposures, allowing analysis of lateral variation in facies. In general this locality is typified by trough cross-bedded facies varying strongly in character along the outcrop, alternating with rare plane beds and with more abundant and variable cross-laminations. The transition to the overlaying Manitoulin Dolostone starts typically with a layer containing wave ripples, overlain by bioturbated calcareous sandstone and shales, grading upward into shaly bioturbated bioclastic thin dolostones of the Manitoulin. Unique to this locality is the presence of laterally extensive, locally scoured-out shale layers in the upper (2/3) cross-bedded part of the Whirlpool (Fig. 21, Facies I). The following features are exposed from the base up: 1. The topmost layer of the Queenston Formation (J) is characterized by a bleached gray shale layer, locally heavily mudcracked. 2. The lowermost unit of the Whirlpool is trough cross-bedded, it shows a fining upward sequence, and has the lowermost 15 cm heavily mineralized with pyrite. 3. The overlaying horizon is generally plane bedded although locally it can be laterally replaced by ripple cross-laminations. 4. A siltstone to mudstone facies grading-up into fine sandstone has well developed ripple cross-laminations showing good ripple drift in finer sandstone layers. Convolute laminations develop locally.

86 Figure 21. Composite stratigraphic section of the Milton Quarry. -*^X Cross-beds, ^Qs ripple marks,^/v-a-x wave ripples, ^\f convolute lamination,*'. J \ plane beds, C ^ burrows, -^- calcareous, (2 fossiliferous, O Q mineralized, ^^ vugs, ** clay pebbles, i shale.

87 65 Lrtholog MJ Facies M H? (11 -E2 C1 ra mm lj

88 The convolute laminations bed is overlain by shales (5-9 cm), rather continuous along the quarry face, except where they are eroded out. It contains some silt starved ripples. To date no macro-fossil have been observed in this layer. 6. A highly variable trough cross-bed facies overlies the shale unit. The troughs may be up to 20 m long, and their cosets (up to 2 m each) consist of up to four sets, each ranging in thickness between 3 to 120 cm (av. 50 cm). This trough unit cuts down deeply into the section toward the north. Sigmoidal cross-beds are present (Fig. 14A). 7. The start of the upper transition is marked by a bed (3-28 cm thick) with well developed wave ripples. 8. The transition to the Manitoulin Dolostone is invariably characterized by the transition facies made up of highly bioturbated sandstone interlayered with thin shale and calcareous fossiliferous siltstone. The rocks of the Milton quarry have no "reed". They have been mined primarily for aggregates and for silica grit and ganister. Hewitt (1969) reports on the quality of this material as silica sand (Table 2). Table 2. Chemical analysis of sandstone from the Milton area (Hewitt, 1969) Si0 2 A Fe 20 3 MgO CaO K 20 Ti0 2 LOI TOT OU

89 BROWN'S FARM -BARNES (Former Inglewood, Handy) (Lot 19, Concession 5, Halton Hills) A large part of the Whirlpool is exposed at this quarry, but only its upper contact with the Manitoulin can be seen. Its major characteristic is the development of the large troughs (channels) facies in its northeastern side, and the lateral just apposition of that facies with a sequence of plane beds, ripple cross-laminations and cross-beds facies along a southwestern wall. The northeastern part of the NE-SW trending wall of the quarry is dominated by large troughs (channels) (Fig. 22B, C; 23A; 14B). They are up to 2 m thick and 15 m wide. The various channels (3-4) show good cross cutting relationship, usually the northeastern ones cutting into the southwestern ones, thus showing lateral migration of the channels toward the northeast. The internal structure of the foresets varies. Generally the beds of the northeastern troughs are plane bedded. Those of the southwestern troughs acquire more ripple cross-laminations. Some of the troughs have large concentrations of clay pebbles forming shale pebble sandy conglomerates at their center. The paleocurrent of the major troughs is to the NW (300 0 ). However, back-currents (120 0 C) are recorded locally in ripple cross-laminations superimposed on the foresets. This large trough facies cuts into the more extensive sequence of the SW wall, which is characterized by well developed plane beds, occasionally in undulating (swale) type units, locally disected by medium scale trough cross-beds (Figs. 22A, D; 14C). The paleocurrents measured in these cross-beds vary between and The lower (2/3) part of the Whirlpool is capped everywhere by thin beds of sandstone showing wave ripples with paleocurrent trends to *.

90 Figure 22. Composite stratigraphic section for two facies of the Brown's farm Quarry. The lateral variation along the walls of the quarries are shown in the skematic cross-sections A-D, B-C. For symbols see Fig. 21 and Fig. 25.

91 69 Thickness Paleo metres Litholog current Fades Thickness metres 3 T H A2 D mm mm

92 Figure 23. Quarry walls. A. Wall C of Brown's Farm Quarry showing large troughs (channels), B,C. Working wall of the Rice and McHarg Quarry showing shallow cross-beds and swales. See also cross sections F-G, Figs. 25, 26.

93

94 Locally the wave ripples are underlain by a thin bed of plane beds with paleocurrent to the north. Above these beds there is the transition (Whirlpool) facies, characterized by heavily bioturbated sand, grading up into the Manitoulin bioturbated bioclastic calcareous sandstone to dolostone. zone (Fig. Few tnudcracked layers are present in the Whirlpool transition 8C). Only a minor part of this quarry shows sandstone with good reed. The quarry has been used primarily as a source of aggregate (Hewitt, 1969). Its commercial operation has been discontinued, but stone is occasionally extracted from the plane beds facies for limited local use. RICE AND McHARG QUARRY (Lot 21, Concession 5, Halton Hill) (Figs. 23, 24, 25, 26, 27) This quarry exposes the middle and upper part of the Whirlpool and its contact with the overlaying Manitoulin (Fig. 24). It offers one of the best three dimensional view of the stratification and of the numerous sedimentary structures of this sandstone. The features can be observed in wall exposures cut at different orientations, and on bedding planes exposed on the floor of the quarry (Figs. 23, 25, 26, 27). The major characteristic of the Whirlpool Sandstone at this locality is the interlayering of a variety of cross-beds and plane beds (Fig. 26). Wide (10 m) and long (20 m), but thin (20-30 cm) cross-beds with rather shallowly sloping foresets characterize the floor of the quarry, particularly in its northeastern area (Figs. 25, 26, 15E). Trough cross- beds with steeper and narrower dimensions are common. There are two major sets of cross-beds, one trending westward with steeper foresets generally rich in clay pebbles, and a second system trending northward generally

95 having less clay pebbles (Fig. 25). These cross-beds cut into and are interlayered with plane beds. The ripple cross-lamination facies has seldom any great thickness in the vertical walls, although a great variety of ripple marks is exposed on the bedding planes (Fig. 25). Lunate ripples, linguoid, interference, and ripple fans downstream from cross-beds (dunes) are numerous. However, the ripple marks are invariably peeled off and overlain by plane laminations. It is hypothesized that much of the "plane beds" seen in the vertical walls may actually contain thin residual ripple cross-laminations alternating with true plane beds (Fig. 26). Plane beds are commonly horizontal. However, plane laminations are also developed in large wavelength swales and in flatter cross-beds (Figs. 23B, C; 24). In trying to understand the lateral and vertical relations between the various facies observed in the walls and on the floor of the quarry, one should visualize a setting where wide and relatively thick beds containing both ripple cross-laminations and plane laminations were formed and were disected to various depths by cross-beds. Some cross- beds could have been associated with migrating bars, others with wide channels tunneling nested sets of three-dimensional dunes. Some of the troughs seen in various parts of the floor can be correlated to cross-beds exposed on the walls (Figs* 16C; 25, 26). Such a three-dimensional irregular cross-bedded envelope encloses disected remnants of plane beds and ripple cross-laminations. The upper transition zone, above the solid Whirlpool Sandstone is characterized at one site by a wide, cm deep channel partially filled with a shale matrix and a fossiliferous (gastropods) clay pebble conglomerate (Fig. 26, sect. Aj). This lower fill is capped by a thin sandstone layer bearing wave ripple marks. The Rice and McHarg quarry has been and still is one of the most productive quarry of the region. It has good quality sandstone with good

96 Figure 24. Composite section of the Rice and McHarg Quarry

97 Thickness Paleo metres Litholog current Facies mm 75

98 Figure 25. Map of the sedimentary features seen on the floor of Rice and McHarg Quarry.

99 COVERED AREA ggg HORIZONTAL BED 10 20m Sa PLANE BED gg TROUGH CROSS-BED EXHUMED SLIPPAGE STRAIGHT RIPPLES IRREGULAR LINGUOID RIPPLES TROUGH LINGUOID RIPPLES RIPPLE FAN OBLIQUE RIPPLES CURRENT CRESCENTS MUD PEBBLES PALEOFLOW DIRECTION o BUILDINGS 77

100 Figure 26. Skematic cross-sections of the walls of the Rice and McHarg Quarry (see location in Fig. 25).

101 79 LU ECM *- O KVUI

102 Figure 27. A,C. Fracture pattern and slopes of beds of the Rice and McHarg Quarry, B. "Feathering" of thick beds (plane beds of the New Smithson Quarry.

103

104 reed. There is very low percentage of waste. The sandstone is easily mined also because it is conveniently broken in large slabs by two sets of joints (Fig. 27C) trending respectively east and north. One localized trend of intense fracturing occurs at the hinge of a monocline (fig. 27A, C). In this quarry, similarly to other localities, the Whirlpool beds change from approximately horizontal attitudes to local steeply dipping (9 0 ) surfaces over a short distance (Fig. 27A). BROCKTON QUARRY (Lot 18, Concession 6, Halton Hill) (Fig. 28) Only the upper part of the Whirlpool and the lower beds of the Manitoulin are exposed at this quarry. The lowermost exposed unit is characterized by a thick (95 cm) trough cross-bed (Fig. ISA) trending westerly (270 0 ). It is overlain by a tabular cross-bedded unit trending to the northwest (355 0 ), and containing numerous clay pebbles along the bottom. A plane bedded facies with clay pebbles and good splittability overlies the cross-beds. These plane beds have paleocurrent direction towards The overlaying wave ripples instead show a trend in paleocurrent. The bioturbated sandstones and biolastic dolostone of the transition facies and of the Manitoulin cap the exposure. NEW SMITHSON QUARRY (Lot 26, Concession 8, Halton Hill) (Fig. 29) The upper part of the Whirlpool and the lower part of the Manitoulin Dolostone are exposed at this quarry. The Whirlpool is characterized by a thick (110 cm) lower interval of plane beds, overlain by ripple cross-laminations locally containing numerous clay pebbles, overlain by plane beds and storm layers of the transition (Whirlpool) facies. Burrowed bioclastic dolostone with thin shale interlayers characterize the Manitoulin Dolostone.

105 Three major features are typical of this outcrop: 1. No cross-beds are present. 2. The plane bedded facies is for the most part (95 cm) red in colour and much finer ( ) than the overlying ripple cross-laminated facies which shows an upward fining from 2.0 to Although the wide spacing of the joints makes extraction of the plane bedded facies difficult, once blocks are removed by feathering (Fig. 27B), they can be readily splitted along planes containing good parting lineations. 3. This is the only outcrop where the storm layers of the transition (Whirlpool) facies show strong lensing, some scouring, and undulating plane beds resembling (in two dimensions) the hummocky cross stratification (HMS) of Harms et al. (1982) (Figs. 10C, 11D, 29). STRUCTURAL SANDSTONE QUARRY (Lot 26, Concession 9, Halton Hill) (Fig. 30) Large parts of the Whirlpool and of the overlying Manitoulin are exposed at this locality. The major characteristic of this quarry is the presence of large troughs (channels) in the lower 2 m. These troughs have width greater than 25 m and have foresets dipping The lower (1.6 m) parts of the troughs have ripple marks superimposed on the foresets. The ripples trend toward Parts of the foreset show plane laminations. Occasional lunate enigmatic small traces occur in the lower meter of the exposure, possibly associated with organic activity (Fig. 30). The large trough facies is overlain by a thin interval (0.30 cm) with wave ripples having a variable paleocurrent direction from to (Fig. 20A). A horizontally bedded, poorly laminated facies (32 cm thick) caps the Whirlpool sequence. This is overlain by bioturbated sandstone and dolostone interlayered with shale beds.

106 Figure 28. Section of the Brockton Quarry.

107 Thickness Litholog metres 3 Paleo current Facies H 2 t CO O mm 85

108 Figure 29. Section of New Smithson Quarry.

109 Thickness..iu. Paleo4. metres Litholog current Facies M H G2 re1 A mm

110 Figure 30. Section of the Structural Sandstone Quarry

111 Thickness metres, Lltholo2!thftuw current Paleo H s s E2 D mm

112 Core drilling indicates approximately 20 feet of gray sandstone at that locality (Hewitt, 1969). It is reported that this stone was used at the University of Western Ontario and in Casa Loma in Toronto. Much of this material would require sawing to be used as building stone. HILLTOP QUARRY (Primo Argo) (Lot 26, Concession 10, Halton Hill) (Fig. 31) The whole of the Whirlpool sequence and the contacts with the underlying Queenston and the overlying Manitoulin are well exposed. The topmost layer of the Queenston is comprised of a greenish-gray bleached thin shale bed. Whirlpool. This is sharply overlain by the fine well cemented sand of the The sole of the Whirlpool sand is an undulating surface with mudcracks and various protuberance, some resembling pseudo-trails (Fig. 8D). As in other parts of this Milton-Inglewood area, the lower 15 cm of the Whirlpool is very dense and intensely mineralized primarily by pyrite. The facies association of the Whirlpool at this quarry is characterized by: 1. A basal thick (130 cm) cross-bedded (trough) coset. Mud pebbles are common in the foresets. 2. The main sand body is fine grained (up to ) and has trough ripple cross-laminations. Toward the top of the facies the angle of climb of the ripples becomes significant, either because of changed conditions of sedimentation, or changed direction of paleocurrent allowing a more longitudinal view of the structure along the outcrop (Figs. 17D, 19C). In several instances, very thin interlayers of plane laminations Indicate that the ripples were recurrently peeled off. Toward the top of the facies several very thin clay drapes have formed on the ripple cross- laminations. In one instance a well developed thin interval of convolute laminations occurs.

113 The plane bed facies is present in two thin intervals at two distinct stratigraphic horizons. One plane bed horizon occurs at the base of the rippled zone, together with some fine grained ( ) laminae. Thin interlayers of ripple cross-laminations are present as well. A second cm thick horizon of plane beds is present at the top of the main ripple cross lamination facies. 4. The upper transition to the Manitoulin is comprised of a lower wave rippled interval, overlain by plane beds and sandstone-shale interlayers with the sandstone units thinning progressively upwards. 5. The Manitoulin contains highly bioturbated calcareous sandstones to silty, bioclastic dolostones, interlayered with shales. The Hilltop quarry shows variable paleocurrent directions, ranging from northeast-northwest quadrants indicated by the lowermost cross-beds, to northeastern directions indicated by the plane beds and trough crosslaminations, to prevalently southwestward direction indicated by the wave ripple marks of the transition zone. Except for a small amount of flagstone retrieved by splitting the plane beds, this quarry has produced mill blocks, ashlar, sills, steps and capping (Hewitt, 1969). DEFOREST BROTHERS QUARRY (Lot 4 S 5, Concession 3, Caledon) (Fig. 32) This is the northernmost exposure studied. The whole Whirlpool sequence is exposed and shows several unique features, the most notable ones being the absence of cross-beds, the presence of large swale, and the red colouration. The lowermost unit (70 cm) is characterized by gray plane beds locally subdivided by two thin lensing layers of ripple marks* The

114 Figure 31. Composite section of the Hilltop Quarry

115 Thickness...,. Paleo r. metres Litnotog current Facies G1 A2 A2 C2 J mm

116 Figure 32. Composite section of the DeForest Quarry.

117 Thickness Litho,0ff Fa : metres Llinoio2 current racies M H B B A mm 95

118 lowermost cm are heavily mineralized at the contact with the Queenston. The lower plane bedded facies Is abruptly and locally erosionally overlain by a thick (greater than 2.55 m) swale facies (Fig. 16D). The swale facies can be subdivided Into two parts by an Intervening, thin, ripple cross-laminated unit. The lower swales are characteristically red (5R 5/2) in colour. The beds have plane laminations and good splittability on the flanks, loosing it somewhat toward the centre of the troughs. The upper swale is gray and its beds have trough cross-laminations. This gray swale facies grades laterally into a steeply (24 0 ) dipping ripple marked surface possibly representing a large bedform such as a bar or a submerged part of a beach. The northward edge of the quarry and the extractable zone is delimited by an intensely fractured, uplifted zone. This fracturing is relatively recent as the joints are all open. It may be associated with the pressure variations imparted by the Pleistocene glaciers, and differential response (flowage) of the underlying Queenston shale. The upper transition zone to the Manitoulin Dolostone starts as usual, with a layer with wave ripples and continues upwards with sandstone and shale interlayers. The paleocurrent direction is consistently toward the north- northwest, throughout the Whirlpool except in the uppermost transitional layers where it switches to a southwest-northeast trend.

119 OTHER FEATURES OF THE WHIRLPOOL SANDSTONE SUMMARY OF STRUCTURAL CHARACTERISTICS All along the Niagara Escarpment west of Lockport (W, Fig. 2) the Whirlpool shows some strong similarities In Its lower contact with the Queenston and In Its transition to the overlying marine beds of the Medina unit. The lower contact Is consistently sharp, flat to slightly undulating, but no deep cut-and-fills have ever been observed. The sole of the Whirlpool Is marked consistently by mudcracks and by shallow differential loadings, and enigmatic traces some resembling organic traces (Seyler, 1981; Salas, pers. comm.). The uppermost 1/3 of the Whirlpool is everywhere characterized by thin shale beds and partings interlayered with calcareous sand and siltstone, generally heavily bioturbated. This upper interval shows storm layers ornamented by various types of plane laminations and wave ripple marks. At some localities mudcracks of definite sub-aerial origin have been observed. This contact is transitional to the overlying units and it is doubtful it would be identified consistently by different operators. The lower 2/3 of the Whirlpool is the most variable and less understood part of the Whirlpool. It is also the part that provides building stone. Everywhere this part is cross-bedded, except at the eastern and western edge of the Whirlpool occurence. In the Rochester area (G, Fig. 2), the coarse, red lower unit of the Medina is correlated with the Whirlpool Sandstone, and does not show cross-bedding. It is characterized by parallel laminations and discontinuous coarse grained laminations and shallow scours much similar to those formed by waves or shallow currents on beaches and bars (Fig. 33A, B). In the Lockport area (W, Fig. 2) cross-beds

120 occur, but they are superimposed on large (2 m thick and more than 20 m wide) lensing units, laterally overlapping and resembling bar-beach features (Sanders, pers. comm.) (Fig. 34C, D). Similar large features have been observed by Seyler (1981) in some outcrops of the Niagara Gorge (R, Fig. 2). In other outcrops of the gorge, the lower part of the Whirlpool is regularly cross-bedded (Fig. 34A, B). The lower Whirlpool is intensely cross-bedded throughout in the De Cew Fall (A, Fig. 2; Fig. 33C) and Hamilton area (FR, Fig. 2; Fig. 34D). In the Milton-Inglewood area heavily cross-bedded or thick ripple cross-laminated units, alternate with plane beds or swales and wide gently sloping structures presenting good reed (Fig. 35). PALEOCURRENTS The overall paleocurrent trend measured in the Whirlpool Sandstone is to the northwest, similarly to that of the overlying units of the Medina. These trends reflect the southeastern Appalachian source of the sediments (Fig. 36). The analysis of the cross-bed azimuths indicate that paleocurrent reversal to opposite quadrants seldom occurs. Notable exceptions exist in the Brown's Farm Quarry and in the De Cew Fall outcrop. However, there is everywhere a consistent indication of a strong mode in the northwestern quadrant, and secondary modes in the southwestern quadrants (locally strong), and in the north-northeast direction. These modes are reinforced by the trends of the ripple cross-laminations and of the a-axis orientations of the clay pebbles at the Rice and McHarg quarry. The parting lineations and the other current lineations indicate a rather consistent paleocurrent to the west and southwest. Local sections have peculiar paleocurrent distributions (Fig. 36, Table 3). The strong northwestern and southwestern modes are well displayed

121 Table 3. Statistics of Directional Measurements. Location Type of Structure No. mean 7 LJK c i "^ Level of significanc C 2 * 90% ** 951 *** gn *East of Hamilton cross-bed *** North of H ami t on cross-bed *** *New York cross-bed * **Niagara Gorge cross-bed *** *De Cew Fall cross-bed ** Milton cross-bed *** Brow 1 s Farm cross-bed N.S. Rice 5. McHarg cross-bed *** North of Limehouse cross-bed * North of Hamilton Ripple cross-lamin N.S. Rice St McHarg Ripple cross-lamin N.S. North of Hamilton Ripple crest orientation 16 1 to *** North of Hamilton Parting lineations *** Rice 6. McHarg Parting lineations *** North of Hamilton Current lineations N.S. Rice Si McHarg Current lineations N.S. Rice 6 McHarg a-axis of clay pebbles 74 i to ** i - perpendicular * data from Martini, 1966; ** data from Seyler, 1981

122 Figure 33. Whirlpool Sandstone and adjacent units at Rochester (A,B) and Lockport (C,D).

123

124 Figure 34. Whirlpool Sandstone at Niagara Gorge (A,B), De Cew Falls, (C) and Hamilton (D; Flock Road).

125

126 Figure 35. Stratigraphic cross-section of the Milton-Inglewood area with tentative correlation. Area with abundant cross-beds; Area with prospective thick plane bedded sandstone*

127 \ l \ l \ - - aoios ow l UJ 1 OD 00 S* H 1 ' ' '-'/f l 105

128 Figure 36. Paleocurrent directions obtained from cross-beds, and other directional sedimentary structures*

129 Current Lineations North of 1 (15) Parting Lineations 4, (11) 107

130 in the bedding planes of the Rice and McHarg quarry. At the same locality, there is locally a strong (90 0 ) divergence between the paleocurrent of ripple cross-laminations and the parting lineations. The strong divergence in paleocurrents in the Brown's farm quarry reflects the behaviour of two facies: 1. The large troughs (channels) flow to the northwest, with local backflow recorded in ripple cross-laminations superimposed on foresets. 2. The east and southeast directions are recorded in cross-beds cutting into plane beds away from the large channels. In all the quarries of the Milton-lnglewood area, the wave ripples of the upper part of the Whirlpool show a SW-NE paleocurrent. No directional data could be obtained from the Manitoulin beds, except for a single measurement ( ) parallel to preferentially oriented bryozoa stems in the Hamilton area (FR, Fig. 2). The available directional information from the Whirlpool Sandstone would not conflict with the hypothesis of two major paleoflows, one perhaps perpendicular and a second parallel or oblique to a shore generally oriented in a SW-NE direction. ENGINEERING PROPERTIES Park (1912) and Hewitt (1969) reported engineering tests done on sandstones quarried north of Milton (Table 4). Although it is not known which facies was sampled, there is no consistent regional variation in the measured parameters. Two layers of different colours were sampled from the same quarry. The red stone shows higher strength, but on the whole its properties do not differ significantly from those measured in gray layers from other quarries.

131 Table 4: Engineering tests of quarried sandstones* Compressive Strength (p. s. i) Max Min Av. Absorption Bulk Specific Gravity Weight per Cubic foot (Ib) Abrasive Hardness Rice S McHarg Hilltop Austin Corner's Norrie (Terra Cotta area) Walker Brothers (grey) Walker Brothers (red) Orangeville (Park 1912) REGIONAL SLOPE OF THE WHIRLPOOL-QUEENSTON CONTACT Local strong dips in some of the Whirlpool beds at DeForest and at the Rice and McHarg quarries have been mentioned before. Some of those dips may have been related to primary local inhomogenity on the surface of the Queenston, to sedimentation features of the Whirlpool, and in part to subsequent movement and fracturing of the units placed under stress by tectonic and glacial activities. At a regional scale, the contact between the Whirlpool and the Queenston slopes irregularly toward the southeast, away from the Algonquin arch. Flat wide areas, such as in the Limehouse-Terra Cotta area, alternate with steeply dipping zones (Table 5). This variation may be indeed associated to an inhomogenous surface of the Queenston prior to sedimentation of the Whirlpool Sandstone. Preliminary analyses do not indicate obvious relations between the changes in slopes of the contact, the altitude of the quarries, and the occurence of thick red coloured intervals in the Whirlpool.

132 Table 5: Approximate elevation of the Queenston-Whirlpool Contact. Location Elevation E m (ft) Distance D km E /D Clappison Corners (Hamilton) Rattlesnake Area Milton Area (Barnes Quarry) (550) (750) (875) Limehouse Area Terra Cot t a Area Fer nd ale Area Inglewood Area (DeForest Quarry) (1000) (1000) (1125) (1200) DISC.USSION ENVIRONMENTS OF DEPOSITION Various hypotheses on the origin of the Whirlpool Sandstone have been proposed, varying from aeolian sand, to shallow marine deposits. Bolton (1957) indicated that "any theory advanced for the origin of these sediments should explain: (1) the gradation of white to grey sandstone eastward into red, coarser grained sandstone, (2) the easterly increase of impurities combined with a decrease in degree of sorting, (3) b the presence of mud-galls (shale pebbles) and grey shale lenses both along the horizontal bedding planes and along the inclined foresets of the cross bedded planes, (4) the limited size of the cross-bedding, suggestive of O aqueous rather than aeolian origin, (5) the presenjl of both well-rounded, frosted and subangular, clear quartz grains, (6) the predominance of only the most stable detrital minerals, and (7) the reasonable constancy in thickness along the Niagara Escarpment with westward thinning".

133 Undoubtedly the uppermost part of the Whirlpool (transition facies) is of marine origin and it shows a deepening sequence from well developed current and wave ripples grading into and locally alternating with plane bedded sandy storm layers and fossiliferous shales. In most cases ths upper units are intensely burrowed and have a progressively upward increase in calcareous content grading into the argillaceous silty sandy dolostone of the overlaying Manitoulin Formation. Where the Manitoulin is absent as in the De Cew Falls, Niagara Gorge and Lockport areas, the Whirlpool grades upward into fine grained shale bearing marine fossils such as Crinoids and few Pelecypods. The major probem in the interpretation of the Whirlpool is in determining the environments of deposition of the lower two thirds of the unit. This lower Whirlpool has been interpreted either as an aeolian, sand (Grabau, 1913; Williams, 1919; Holstein, 1936; Lockwood, 1942; Fisher, 1954), a shallow marine sand (Bolton, 1957; Martini, 1966, 1974, 1982), or a braided stream deposit (Middleton, 1982; Middleton and others 1983). Direct evidences for the aeolian origin of the lower Whirlpool are the textural and mineralogical maturity of the sandstone and the variable cross-beds. "Negative" evidences that support the continental origin are the absence of wave ripples and of fossils, except for few collophane (phosphatized) pellets, and algal spores. Indirect evidences are related to observations and interpretations of the behaviour of the top surface of the Queenston during deposition of the lowermost Whirlpool beds (Fisher, 1954; Seyler, 1981). The first of such observations is that the mudcracks at the top of the Queenston are particularly well preserved and are filled with very well sorted mature sand blown on a drying, exposed surface. Secondly, whereas the Whirlpool is generally grey in colour, occasional red

134 intervals and tongues are found. Furthermore, no red clay pebbles have ever been observed, reworked in the sand. This has been considered by some students to indicate that the Queenston surface was protected by wind-blown sand before the transgression and erosion of the red material could have occurred (Fisher, 1954). The above evidences are weak, in the study area, and more plausible explanations exist. There is not yet sufficient data to be able to exclude the possibility of few remnant aeolian sand lenses or the presence of scattered wind-blown sand grains in the various layers. However, the limited size of the cross-beds and of the cut-and-fills, the presence of locally abundant clay pebbles associated with the cross-beds, the numerous occurrences of current crescents, current ripples, ripple fans, exumed slipfaces of sand waves, plane beds, parting lineations, good sorting of heavy minerals in laminae and current lineations, and other similar sedimentary structures all indicate a variable subaqueous environment of deposition. Bolton (1954, p. 11) suggested that for the Ontario region "the Whirlpool was deposited as marginal sediments derived from the east and laid down on the undulating and mudcracked Queenston surface by transgressing shallow seas under reducing conditions". Seyler (1981) relied heavily on her interpreted presence of burrows in the lowermost layer of the Whirlpool, and interpreted the Whirlpool-Fish Creek shale sequence in the Niagara Gorge as a barrier-lagoon system. Middleton (1982) and Middleton et al. (1983) suggested that the persistent lack of macro-fossil, the persistent westward paleocurrent direction, the presence of large channels filled with large cross-beds, the nested and variable behaviour of smaller cross-beds, and the interfingering and interstratification of plane beds and ripple crosslaminations all indicate that "facies and paleocurrents of the lower part are more consistent with a braided fluvial than shoreface or tidal origin".

135 As it has been demonstrated time and time again in the geological literature of northeastern America, all these authors may be partly correct, as they have focussed their attention to, or have been influenced by, parts of the deposits. The fundamental concepts to keep in mind in interpreting these thin, widespread Lower Silurian units are: 1. The units are time transgressive. 2. However flat they may be, the time lines do not parallel the lithological boundaries, but they transgress lithofacies within and between st r at ig r aphic unit s. 3. Only the structures and deposits formed during extreme events are preserved in the stratigraphic sections. Deposits of fairweather and less intense storms are present, if at all, as remnant lenses. 4. The Ontario region was in a subtropical region of the southern hemisphere during Lower Silurian times. 5. The subaerial part of the landscape was not efficiently protected by vegetation, except for algae, as the major land plants were not yet evolved. The landscape of the lowermost Silurian times is envisaged here as a very flat subaerial and subaqueous area rising gently toward the Taconic (Appalachians) and being innundated from the west by shallow seas. Wind must have had a significant role in the erosion and dispersal of sediments. Similarly, seasonal rainstorms must have lead to the formation of unrestricted, wide, ephimeral braided streams in inland parts. Input of sediments along preferred parts of the coast, may have occurred from many channels without the formation of a recognizable delta (Fig. 37). As the sea transgressed, some of the coastal and continental deposits must have been reworked by waves and longshore currents. There is little direct

136 Figure 37. Environmental model for the Whirlpool Sandstone. section and model are not to scale. Regional cross-

137 115

138 evidence of tidal action, unless some of the cross-beds are interpreted as tidal inlet or larger tidal embayment deposits. Nearshore bars and beaches were formed, and storm deposits were spread out onto the antecedent littoral and sublittoral zones (Fig. 37). Longshore current direction and strength would have been determined by the local shoreline configuration. However, because of the southern hemisphere location, an overall clockwise trend could have been superimposed along the westernly facing shoreline, generating strong southwestern modes in the paleocurrent records (Fig. 37). CONCEPTS IN AID TO EXPLORATION OF ROCKS WITH GOOD REED Sedimentary structures and environments Certain primary sedimentary structures are formed under specific fluid flow and grain size conditions (Fig. 9). In nature, superimposition of structures occurs responding to variable (unsteady and non-uniform) flows. If the sediment supply is not sufficiently high, changing flow condition may replace partially or totally pre-existent sedimentary structures. Because the types of flow may occur in a variety of settings, single structures are not specific indicators of environments of deposition. However, well defined landscapes foster non-random variations in flows. Therefore, the resultant lateral and vertical sequences of structures, aided by other characteristics of the sediments such as fossils, mineralogy, textural parameters and the geometry of the deposits, can lead to the interpretation of environments of deposition. Conversely, but not as easily, if the overall paleogeography of a geologic period is known for a region, some suggestion may be provided on the probability of finding a sizable amount of a certain feature, such as a type of rock or a type of porosity in a particular area. The unknown parameter in this prediction is

139 the rate of deposition which would dictate whether the whole sedimentological record of an environment is preserved in the stratigraphic column, or whether it is reworked or eroded leaving a partial distorted picture of the original accumulation. Rocks with good reed Rocks that can be readily split parallel to the bedding planes are referred by quarrymen as having a good "reed". This splittability is associated with preferred fabric arrangement of grains along parallel laminations in fairly well cemented rocks. Parallel laminations with a workable reed can be formed under various conditions in: a) upper-stage plane beds b) standing sand waves under supercritical flow conditions c) lower-stage plane beds d) transcurrent laminations e) Apparently massive sands, which are usually formed under supercritical flow conditions. Their apparent masslveness is due to the limited sorting of the darker heavier minerals or coarser lighter minerals in laminae. Nevertheless, some sorting and some preferred fabric arrangement occur during the rapid sedimentation of these units, and they posses good reed. f) Parallel laminations with workable reed can also be found along foresets of large subaqueous dunes and sand waves. The sorting in laminae is probably related to a continuous creep (sediment gravity flow) of grains along the foresets or, for the flatter units, to reattachment of supercritical or near-critical flows. It is not known whether grain flows in subaerial sand dunes lead to a good reed. Some splittability

140 should be present although the sand tongues typical of this mechanism of sediment transport may limit the lateral extension of the laminae. The best reed is found in very fine to medium grained sandstone with upper-stage plane beds (Fig. 9; Allen 1982). Under these conditions "parting lineations" (Crowell, 1955) and "parting step lineations" (McBride and Yeakel, 1963) are well developed (Figs, lob). The parting lineations are characterized by small (few grain sizes high and few mm wide) greatly elongated downcurrent (several cm to tens of cm) ridges and hollows placed in en-echelon pattern. The hollows between ridges are commonly flat bottomed, whereas the ridges themselves are generally rounded in profile (Allen, 1982, p. 261). Usually the ridges are formed by the coarsest available sand size on the beds. instead in the hollows. Mica and heavy minerals concentrate Under lower flow strength, ripple marks would develop instead of plane beds (Fig. 9). The association of ripple marks and parallel laminated sand with parting lineations is commonly observed. In many instances the parallel laminations are thin and they develop along flat erosional surfaces during the peeling-off stage of the pre-existing ripples and cross-beds as the flow velocity increases and/or the flow depth decreases. This peeling- off phenomena has been observed frequently in the floor exposures of the Rice and McHarg quarry. When the peeling-off phenomenon! is repeated regularly and for a long time, a fine interlayering of plane beds and remnants of ripple cross-laminations is generated. In many instances the thin (few millimeters) remnants are not distinguishable as crosslaminations, and the whole sequence looks parallel laminated, albeit with slight irregularities (shallow scours). This type of sandstone has a good, but not optimum reed, and can be readily split.

141 A similar feature is the so called "transcurrent lamination". This is formed generally under low net rate of sedimentation. There are several mechanisms to explain them (Allen, 1982, v. l, p. 359). One such a mechanism would suggest that these laminations develop when the size of the sand is coarse to very coarse, and the grain size does not differ much from the height of the resulting ripples. Under these conditions the foresets of the cross-laminations are not recognizable and the resultant features look parallel laminated (lower stage plane laminations). A second mechanism is related to more regular ripples (Smith, 1972). If the ripples are very uniform and a good sorting occurs, such that the coarser material is consistently deposited at the toe of the foresets, and the finer material is deposited higher up, then the resultant structure shows plane laminations alternating the coarse and fine grain fractions as the unrecognizable cross- laminae migrate downstream. The sandstone with transcurrent laminations can be split along a fairly good reed. Parallel laminations are not restricted to horizontally bedded sandstone. They can develop as undulating plane laminations under upper- stage flow regimes, or along the foresets of slightly coarser grained subaqueous dunes formed in waters shallower than that required for their full development (Allen, 1982). At the limit, in shallow waters and or under fast flow conditions, swales can form which contain parallel laminated sandstone with good reed (Fig. 10). Parallel laminations are not limited to unidirectional flow conditions. They can readily form under tidal or wave conditions. Good parallel laminations with a relatively extensive lateral continuity form consistently in sandy beaches (Fig. 10).

142 Rocks with poor reed Rocks that do not contain a good reed and require sawing to be used as building stones, are characterized by ripple cross-laminations ("feathery reed" of the quarrymen) and by small to medium trough cross-beds ("kurls" of the quarrymen). Poor reed is also found in units that have large cross-beds with ripple cross-laminations superimposed on their forests. These features form under low to intermediate flow conditions, within a relatively restricted grain size range (Fig. 9). Note that the ripple marks do not form in very coarse sand and that dunes (cross-beds) do not form in very fine sand. The quality of reed is reduced drastically also in parallel laminations where obstructions occurs, such as clay pebbles which generate inhomogeneity directly, or foster formation of a variety features such as current crescents (Fig. 11C). CONCLUSIONS (Exploring for rocks with good reed in the Milton-Inglewood area) The decision of opening a quarry in a certain area depends on many factors, the geology of the sandstone unit being just one of them. The economics related to the market conditions, to removal of the overburden, to the type of operation which ultimately dictates what rock can be used and what has to be discarted, play a major role in the decision. The sedimentological analysis of the rock unit can only contribute added information to the practical experience of the quarryman and help in pointing out more favourable areas. The quality of an area for mining flagstone depends on the amount of suitable rock. Whereas the paleoenvironmental conditions may have fostered the formation of sediments

143 with parallel laminations, these may have been subsequently disected by small and large channels (cross-bedded units: kurls) leaving a discontinuous, uneconomical amount of suitable rock. In the Hamilton-Inglewood region, thick deposits of parallel laminated sandstone are most likely to be found in the Inglewood and in the Limehouse-New Smithson quarry areas. occur also in the Inglewood area. occurs south of Limehouse (Fig. 35). Rocks with good reed are likely to A third area that warrants consideration Whereas, it is true that the probability of finding thick units with good reed decreases southward and it e becomes almost rvihti in the Milton-Hamilton region, it is also true that between Limehouse and Milton plane bedded sandstones alternate with cross- bedded and cross-laminated unit (Fig. 35). If the preliminary sedimentological model presented here has any validity, it is also possible that a non heavily chanalized zone similar to the one of Limehouse occurs in this transitions area. The Limehouse-Milton area is most promising also because it has thin overburden and it has been sparsely explored (Harvey, pers. comm.). The Hilltop-Terra Cotta-Chaltam area has already been intensely exploited, and the remnant outcrops indicate that parallel laminated sandstone occur, but not in sufficient quantity to warrant a large quarrying activity without considering also the possibility of exploiting the more abundant ripple cross-laminated and cross-bedded sandstone.

144 REFERENCES Allen, J.R.L Current Ripples, North-Holland, Amsterdam. 433 p. Allen, J.R.L Sedimentary Structures, their character and physical basis, 2 vol. Elsevier. Alling, H.L Petrology of the Niagara Gorge sediments, Rochester Acad. Sci., Proc., v. 7, p Berry, W.B.N. and Boucot, A.J Correlation of North American Silurian rocks: Geol. Soc. America, Special Paper 102. Bolton, I.E Silurian Stratigraphy and Palaeontology of the Niagara Escarpment in Ontario. Geol. Surv. Can. Mem. 289, 145 p. Bond, I.J., Liberty, B.A. and Telford, P.G Paleozoic Geology, Brampton, NTS 30 M/12, Ont. Division of Mines, Map Chaivre, K.R. and Sanford, J.T Alexandrian-Niagaran regional correlation, in J.T. Sanford, I.P. Martini, and R.E. Mosher. Niagaran Stratigraphy: Hamilton. Michigan Basin Geological Society, 89 p. Crowell, J.C Directional current structures from the pre-alpine Fhysch., Switzerland. Bull. Geol. Soc. Am., v. 66, p Dott, R.H., Jr Wacke, graywacke and matrix. What approach to immature sandstone classification? J. Sed. Petrology, v. 34, p Fisher, D.W Stratigraphy of the Medina Group, New York and Ontario. Amer. Assoc. Petroleum Geol. Bull. v. 38, p Fisher, D.W Correlation of the Silurian rocks in New York State: N.Y. State Mus. Sci. Service, N.Y. Geol. Survey, Map and Chart Series, No. l. Folk, R.L Petrology of sedimentary rocks. Hemphill's, Austin, 154 p. Friedman, G.M., Sanders, J.E. and Martini, l.p Sedimentary Facies: Products of sedimentary environments in a cross section of the classic Appalachian Mountains and adjoining Appalachian Basin in New York and Ontario. International Associations of Sedimentologists Guidebook, lith International Congress, McMaster University, Canada, 350 p. Gietz, The Whirlpool Sandstone. Unpublished M.Se. Thesis, McMaster University. Grabau, A.W Physical and faunal evolution of North America during Ordovicic, Siluric and early Devonic time. J. Geol., v. 17, p

145 Grabau, A.W. 1913* Early Paleozoic delta deposit of North America. Geol. Soc. Am. Bull., v. 24, p Harms, J.C., Southard, J.B. and Walker, R.G Structures and sequences in clastic rocks - Short course No. 9, Soc. Econ. Paleont. and Mineralogists - Tulsa, Oklahoma. Hewitt, D.F Building stones of Ontario, Part IV: Sandstone; Ontario. Dept. of Mines, IMR 17, 57 p. Hewitt, D.F Industrial Mineral Resources of the Brampton Area; Ont. Dept. of Mines, IMR 23, 22 p. Holstein, A Heavy minerals of the Silurian rocks of the Niagara escarpment. Unp. Ph.D. thesis. Toronto Univ. Knight, W.V Historical and Economic Geology of Lower Silurian Clinton Sandstone of Northeastern Ohio: Am. Assoc. Petroleum Geologists Bull, v. 53, p Koepke, W.E The Whirlpool Formation as building stone, Georgetown area, Ontario. Unpubl. B.Se. Thesis. Geol. Dept., University of Western Ontario. 34 p. Kottlowski, F.E Measuring stratigraphic sections. Holt, Rinehart fit Wisnton, N.Y. 253 p. Lockwood, W.N The Stratigraphy and Paleontology of the White Medina Sandstone. M.A. Thesis, Univ. of Buffalo. 25 p. McBride, E.F. and Yeakel, L.S Relationship between parting lineation and rock fabric. J. Sed. Petrology, v. 33, p Martini, I.P FORTRAN IV Programs for grain orientation and directional sedimentary structures - McMaster University, Dept. of Geology. Tech. Memo 65-2, 10 p. Martini, I.P The sedimentology of the Medina Formation along the Niagara Escarpment (Ontario and New York State). Unpub. Ph.D. Thesis, McMaster University, 420 p. Martini, I.P Regional analysis of sedimentology of the Medina Formation (Silurian) Ontario and New York. Am. Assoc. Petrol. Geol. Bull. v. 55, p Martini, I.P Deltaic and shallow marine Lower Silurian sediments of the Niagara Escarpment between Hamilton, Ontario and Rochester, N.Y. A Field Guide. Maritime Sediments, v. 10, p Middleton, G.V A brief guide to the sedimentology of the Hamilton Area. Dept. of Geology Tech. Memo 82-1, McMaster University, 26 p. Middleton, G.V., Salas, C. and Martini, I.P Whirlpool Sandstone (Silurian), of southern Ontario, braided river deposit? (abs) Geol. Soc. Amer annual conference.

146 Miller, M.A. and Barnes, L.E Palynomorphs from the silurian Medina Group (Lower LLandovery) of the Niagara Gorge, Lewiston, New York, U.S.A. Polynology, v. 6, p Parks, W.A Report on the building and ornamental stones of Canada; Canada Dept. Mines, Dept. No Pettijohn, F.J., Potter, P.E. and Siever, R Sand and Sandstone. Springer-Verlag, 618 p. Sanford, B.V Silurian of southwestern Ontario: Ontario Petroleum Inst. 8th Ann. Conf. Sessiona 5, 44 p. Sanford, J.T., Martini, l.p. and Mosher, R.E Niagaran Stratigraphy: Hamilton, Ontario. Michigan Basin Geol Soc., 89 p. Sanford, J.T Niagaran-Alexandrian (Silurian) stratigraphy and tectonics, iia J.T. Sanford, l.p. Martini, and R.E. Mosher, Niagaran Stratigraphy: Hamilton, Ontario, 89 p. Seyler, B The Whirlpool Sandstone (Medina Group) in outcrop and the subsurface: a description and interpretation of the environment of deposition. Unpubl. M.Se. Thesis. Suny, College of Fredonic. Smith, N.D Some sedimentological aspects of planar crossstratification in a sandy braided river. J. Sed. Petrology, v. 42, p Strother, P.R. and Traverse A Plant microfossils from llandoverian and Wenlockian rocks of Pennsylvania. Palynology, v. 3, p Telford, P.G Geology of the Brampton East map sheet, Map :50,000 issued Ontario Division of Mines. Williams, M.Y The Silurian geology and faunas of Ontario Peninsula and Manitoulin and adjacent islands. Geol. Survey Canada, Memoir 111. Winder, C.G Petrography of Paleozoic Sandstone in Southern Ontario. Ontario Petroleum Institute, 7th Annual Conference, Technical Paper no. 4, 17 p. Yeakel, L.S Tuscarora, Juniata and Bald Eagle paleocurrents and paleogeography in the central Appalachians. Geol. Soc. America Bull., v. 73, p

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