TWO QUATERNARY DEPOSITS IN THE LOWER TEES BASIN

Transcription

1 TWO QUATERNARY DEPOSTS N THE LOWER TEES BASN BY D. J. BELLAMY, M. E. BRADSHAW, G. R. MLLNGTON AND L G. SMMONS The University of Durham {Received 21 February 1966) SUMMARY Two deposits from the Tees basin are investigated for their stratigraphical and pollen-analytical content. A series of marls and lake niuds from Romaldkirk includes material from zones -Vc of the Post-glacial sequence and contained Bos bones. The deposit at Burtree Lane was revealed temporarily during motorway construction and covers zones V-Yl. ts chief feature of interest is the thieli layers of bryophyte peat which constitute the organic material, especially Paludella sguarrosa which occurs in profusion. Other mosses include Acrocladium giganteum, A. cuspidatum, Camptothecium nitens, and the first British Post-glacial record of Helodium blandoicii. The possible developmental history of the deposits is discussed in the light of contemporary floating mat vegetation around some Polish lakes. NTRODUCTON After it emerges from the northern Pennines, the Tees flows across a tract of Boulder Clay and other glacial deposits of Pleistocene age (Wells, 1957). The surface of the till is frequently irregular and small basins filled with Late- and Post-glacial deposits have been discovered, two of which are described in this paper. The first site, near Romaldkirk (NZ 99220), lies more or less where the Tees ceases to flow in a dale and is about 660 ft (200 m) above O.D. The deposit lies in a hollow in hummocky terrain (Fig. ic) close to a river cliff overlooking the Tees. The other site, Burtree Lane (NZ ), is near Darlington (Fig. i A) which is almost in the centre of the lower Tees basin. Whereas the Romaldkirk site is in a small single hollow, the Burtree Lane deposit lies in a basin at 250 ft O.D. (77 m), which was probably an arm of a more extensive low-lying area (Fig. id), some of which is today Juncus-infested grassland. Both sites were discovered as the result of digging operations: the Burtree Lane deposit was opened up during the construction of a motorway and the authors were allowed only a few hours in which to investigate and sample the material. ROMALDKRK Stratigraphy of the deposit {M.E.B.) After an initial exposure the deposit was investigated by means of a Hiller borer. The major stratigraphic units recognized (Fig. ) were: (a) mineral soil; (b) peats and drift mud sometimes containing silt or clay, with occasional twigs; (c) a detritus mud which formed most of the deposit. n this was found twigs of Salix sp., Populus, Frangula alms and Betula sp., leaves of Salix sp., and nuts of Corylus, fruits or seeds of Hippuris, Menyanthes, Fotamogeton sp., Potentilla palustris. Car ex spp., and stems of Fhragmites 429

2 4O D. J. BELLAMY ef a/. communis and unidentified bryophytes; (d) a mud-marl transition found at the sides of the deposit which was a highly calcareous marl with much organic matter (a bud scale of Populus was found in this material); (e) a calcareous shell marl varying in colour Fig.. Locational data. (A) The lower Tees basin showing relief, major rivers and location of the sites; also the Neasham site of Blackburn (1952). Contours in feet. (B) General location of the area. (C) The local topography at Romaldkirk. (D) At Burtree Lane. n C and D the location of the deposit is marked by a black circle and the pecked lines are roads in 196. from white through grey to yellow. The most abundant macrofossils were Chara oospores and freshwater molluscs although quite considerable portions of the basal section of the material were without shells, e.g. -68 cm in bore 2 and cm in bore 6. Other remains were Menyanthes seeds, Potamogeton fruits and a nut of Corylus; (f) basal deposits consisting of grey or blue-grey clays (sometimes laminated).

3 Quaternary deposits in the Tees basin 41 Fibrous peat Marl Bryophyte peat Shell marl Sphagnum peat Detritus mud V V VV Wood Clay and silts AAA i AA Al Till Ericoid - Sphagnum peat Fig. 2. Stratigraphic symbols used in Figs. -8. metres metres Fig.. Diagram of the stratigraphy at Romaldkirk, constructed from boring records. B NP

4 42 D. J. BELLAMY ef az. a compact grey silt or clay-silt laminations. These did not occur in any consistent stratigraphic or spatial sequence. The following molluscs from the shell marls of bore 6 were identified by Dr. M. P. Kerney, Planorbis laevis (Alder) Pisidium nitidum (Jenyns) P. crista (Linne) P. cf. casertanum (Poli) Limnaea pereger (Miiller) Segmentina complanata (Linne) History of the basin A number of depositional stages can be inferred from the stratigraphy and macroremains, (i) The deposition of clays and silts with few macroremains; (2) a period of shell marl deposition throughout the basin. The marl is thickest near the edges and Chara is abundant; () the accumulation of detritus mud with a considerable amount of drifted material: leaves and twigs from trees growing at the sides of the basin plus fruits and seeds from plants of the lake-edge communities. There is little sign of hydroseral development; (4) a drying-out of the lake indicated by a peaty drift mud with clay or silt. Since this material does not encroach gradually from the sides but forms a sealing layer over the top of the underlying deposits it is possible that the drying-out was rapid; (5) all the organic deposits are sealed by a layer of soil, probably downwash accumulated when the surrounding area was disforested. The picture presented is of a normal sequence of deposits with little marginal hydroseral development, probably due to the steep sides of the basin, concluded by relatively rapid drying-out. Pollen analysis {.G.S.) Sampling details (for analysis procedure and pollen diagrams see Appendix). Samples were taken at 10 cm intervals from bore 6, The stratigraphy of this boring was: 0-40 cm Mineral soil, cm Coarse fibrous muddy peat, oxidized. Cuticle fragments of Phragmites, wood fragments, two nutlets of Care.x sp,, occasional fern sporangia and a little silt, cm Coarse detritus muds. Fern sporangia common at 100 cm, Phragmites cuticle at 100, no and 160 cm, Salix leaf fragments at 140 cm and two fruits of Betula pubescens at 10 cm. Wood fragments throughout cm Mud-marl transition with abundant Chara (cf. C. vulgaris L,) oospores, becoming less frequent cm. Occasional wood fragments and two fruits of Betula pubescens at 220 cm. Piece of Phragmites at 200 cm, cm Calcareous marl with some mud, Chara abundant, Cf, Salix leaf at 10 cm and Salix wood at 20 cm, Betula wood at 0 and 60 cm. Remains of Campylium stellatum at 280 cm. Mollusc shells cm, a seed of Nymphaea at 00 cm, cm Calcareous marl with shells. Wood and Chara infrequent or absent, leaf fragments of Betula sp. at 90 cm, cm Marl, only slightly calcareous but Chara abundant. No shells, silts present cm Slightly calcareous marl, becoming clayey at the base, at 620 cm Blue-grey clay, Zo7ies represented {see Figs, 5 and 6), There is a basal three-fold oscillation of arboreal pollen (AP) and non-arboreal pollen (NAP) which suggests the presence of Late-glacial deposits, zones -. The gradual immigration of trees is typical of the Post-glacial period from zone V onwards, and the spectra of the top samples suggest zone Vic.

5 Quaternary deposits in the Tees basin 4 The hydrosere. No clear indication of development is given by either the pollen or the stratigraphy. The former suggests the presence of open water and marginal plants but never in high frequencies and clearly interpretable succession. Potamogeton is the earliest, followed by Nymphaea and with Typha latifolia present throughout. Small amounts of the pollen of Cladium mariscus, Myriophyllum spicatum and a single grain of Tvpha angustifolialsparganium are present. Since Potamogeton and Nymphaea retain the highest frequencies and Typha latifolia is never common, there was probably little encroachment of marginal communities. Filipendula is high throughout and was probably growing at Table i. Romaldkirk: basal samples {NAP not plotted on Fig. 7); percentages of total tree pollen "? 1. S ' '5.^ "5 S cm f s; u a; 4 iace X ' = CO S ha-i ' ^ ^ P dj a sodi -2 CO s the water's edge. The top of the deposit sees the rapid expansion of Cyperaceae and Filicales frequencies as the basin dried out, followed by oxidation which has destroyed the pollen. Forest development: the Late-glacial period, zones -. Pinus and Betula are the only trees present, and B. nana declines through the period. There is some Coryloid pollen. The open nature of the vegetation is indicated by high frequencies of NAP (see Fig. 6 and Table i). Following Bartley (1962) the passing of the tree-line during late zone may be inferred from the successive peaks of Salix and Juniperus, whose zone frequencies may indicate the proximity of the tree-line. Forest development: the Post-glacial period, zones V-V. The AP expand at the expense of the NAP and there is the usual British sequence of immigrations of forest trees. Betula remains high throughout due to a local presence which is corroborated by many macroremains. A gradual entry of Alnus is seen but there is no typical early zone Vila expansion and there is no Tilia. The non-aquatic herbs stay at low frequencies except those of pool or woodland edge communities, e.g. Gramineae (from Phragmites

6 44 D. J. BELLAMY et al. possibly), Cyperaceae, Filipendula, Umbelliferae and Filicales, A composite type of the Tubuliflorae group is present throughout. There are a few occurrences of 'weed' pollen such as Artemisia, Urtica and Chenopodiaceae but these are insufficient to suggest any forest clearance. This interpretation suggests a typical Late- and Post-glacial sequence, the only unusual feature of which is the absence of high Pinus frequencies in zone V. Bos bones. The complete left femur and atlas vertebra of a bovid were found during the excavations. Dr, J, Clutton-Brock reports (personal communication) that they Table 2, Pollen analyses from bone scrapings; percentages of total tree pollen O) ^ CO O O O t (i) Vertebra scrapings i iii 7 (ii) Femur scrapings Line of monolith A A AAA A A i metres metres Fig, 4, Diagram of the stratigraphy at Burtree Lane, constructed from field sketches and photographs, A-F strata referred to in text, are likely to have come from a small female specimen of Bos primigenus. They were not in situ and deposit adhering to them was scraped into tubes by Dr. V. B. Proudfoot and later analysed. The details are as follows, (i) Scrapings from vertebra: coarse detritus mud with calcareous material and wood fragments, probably from the upper part of the detritus mud, (ii) Scrapings from a long bone: calcareous shell marl with abundant Chara and a fruit of Betula sp. The pollen analysis is presented as Table 2. Sample (i), with practically equal Betula and Ouercus and high Vlmiis, suggests the zone Vb/c transition; sample (ii), with high Betula, lower Ulmus, Ouercus and high Coryloid suggests zone V or early zone V, No further conclusions can be drawn from the fragments. n the region, other Bos bones have been found at high altitudes in the Pennines (Johnson, 196).

7 Quaternary deposits in the Tees basin 45 BURTREE LANE Stratigraphy of the deposit {D.J.B. and G.R.M.) Limited time of access to the deposit allowed only the collection of a single set of block samples from the deepest part of the exposure. These samples did not include the 50 cm of mineral soil which sealed the organic material. The general stratigraphy of the deposit constructed from field sketches and photographs is shown in Fig. 4 and the detailed analysis of the monolith is given below. A cm. Mire Forest Peat A. O-OO cm. Brown Wood Peat. Few recognizable contents, Betula (seeds and wood), Gramineae (leaves). A2. ioo-iio cm. Brow-n Wood Peat. Well-preserved,Bf/«/a (fruits, scales, wood); Corylus {nux); Carex rostrata {huit); Phragmites communis (leaf), Bryum pseudotriquetrum, Mnium undulatum, Plagiothecium denticidatum. A cm. Brown Wood Peat. Badly preserved, Betula (fruits, scales, wood). A cm. Brown Wood Peat. Moderately well preserved, Betula (fruit, scales, wood, leaves); Erieoid wood; Carex rostrata (fruit); Viola palustris {seed). B cm. Transition Mire Peat Bi cm. SphagnumjY.r'icoid Peat. Moderately well-preserved, Betula (small amount of wood); Erica tetralix (stems); Calluna vulgaris {stems); Carex rostrata {fruit); Sphagnumplmnulosum. B cm. Sphagnum Peat. Well-preserved, S. teres and S. plumulosum. B cm. EricoidlSphagnutn Peat. Well-preserved, Erica tetralix (stems); Calluna vulgaris (stems); Carex rostrata (fruit); Sphagnum teres; S. plumulosum; Polytrichum strictum; P. commune. C cm. Bryophyte Peat All layers in an excellent state of preservation. Ci cm. Black Moss Peat. Ericoid (stems); Carex panicea (fruit); C. rostrata (fruit); Phragmites communis (leaves); Sphagnum teres (abundant); Camptothecium nitens; Paludella squarrosa. C cm. Golden Brown Moss Peat. Betula (scales and fruit); Carex rostrata (fruit); Camptothecium nitens and Paludella squarrosa (abundant); Acrocladium cuspidatum; A. giganteum. C cm. Dark Green Moss Peat. Carex panicea (fruit); C. rostrata (fruit); Schoenoplectus lacustris (fruit); Pedicidaris palustris (seed); Paludella squarrosa (making up most of the sample); Acrocladium giganteum; A. cuspidatum. C cm. Dark Green to Ochraeeous Moss Peat. Caltha palustris (seed); Menyanthes trifoliata (seed); Potentilla palustris (seed); Salix sp. (seed); Acrocladium giganteum (70% of sample), A. cuspidatum; Chara (oospores). D cm. Black Detritus Mud Very badly preserved: Potamogeton natans (seed); Chara (oospores). E cm. Calcareous Marl Potamogeton natans (seed); Chara (oospores); Sphaerium corneum; PlanorUs laevis; Pisidium obtusale; Valvata piscinalis. F em. Muds and Clays Phragmites communis (leaves and rhizomes); Equisetum fluviatile (internode).

8 46 D. J. BELLAMY e^ a/. The most striking feature of the whole deposit was the excellent state of preservation of the Bryophyte peat layers. The three major components, Acrocladium giganteum, Table. Floristic analyses using the Braun-Blanquet cover index for Lake Wiskolisko {site i) and Lake Prysalek {site 2) in the Maxurian Lake District of Poland la ib 2a zb Betula pubescens*... + Caltha palustris* Cardamine pratensis. +.. Carex chordorrhiza.. +. C. diandra C. dioica C. limosa.. i. C. nigra - - C. panicea*. +.. C paniculata + -H. C. rostrata* Drosera anglica.. +. D. rotundifolia Eleocharis palustris... Epipactis palustris Equisetum fluviatile* - -. Eriophorum angustifoiium. i.. E. latifolium... + Galium palustre +. - { -. G. uliginosum +... Lemna minor +... L. polyrhiza +... Lotus uligtnosus +... Lysimachia thyrisiflora Lychnis flos-cuculi..{ Menyanthes trifoliata* i + Molinia caerulea f- Myosotis palustris -(- +. Nuphar lutea +... Oxy coccus palustris Pinus sylvestris....^ Phragmites communis*. i Scheuchzeria palustris.. -(- ^ Schoenoplectus lacustris* Stellaria palustris. 4. ^, Thelypteris palustris* - i i Typha angustifolia +... JJtricularia minor... ^ Acrocladium cuspidatum* ^ A. giganteum* 2... Aulacommum palustre* -j- i ^ Bryum pseudotriquetrum* Camptothedum nitens* + - ) - +, Drepanocladus vernicosus 2 i i. Marchantia polymorpha - ) -. - )., Meesia longiseta.. 4. Mnium rugicum.. 4. M. seligeri + X.. Paludella squarrosa* 2 Sphagnum plumulosum* S. recurvum ^ j 2 5. teres*.. +. * Species found in the Burtree Lane deposit. Paludella squarrosa and Camptothedum nitens, could be pulled from the profile in easily recognizable tufts each with their own characteristic live colours, although they rapidly turned black on exposure to the air.

9 Quaternary deposits in the Tees basin 47 Suggested developmental history Comparison with extant hydroseres showing a similar sequence of vegetation types allows a tentative scheme for the developmental history of the Burtree deposit to be drawn up. Table gives the vegetation analysis for two lowland sites in the Mazurian Lake District of Poland. Both portray the vegetational zonation along the margin of small lakes through which mineral rich, alkaline waters flow. Site. Lake Wiskolisko (a) Pioneer floating mat. (b) Floating mat developed at the head of the lake and therefore not subject to the main water movements through the lake. Site 2. Lake Prysalek (a) Floating mat over shallow water overlying deep calcareous gyttja. (b) A more stable mat being colonized by Pintis sylvestrts and Betula pubescens. Apart from the major floristic similarities between the zones described and the lower horizons in the Burtree Lane deposit, the most striking feature in common is the development of more mesotrophic conditions over base-rich flowing waters, allowing the invasion of base tolerant Sphagna associated in each case with Camptothecium nitens. The Burtree Lane material graphically shows hydroseral development in a shallow basin which formed an embayment of a large lake system. The deposit of marl, (E), and the abundance of Valvata piscinalis, Acrocladium giganteum and Paludella squarrosa indicate flowing, mineral-rich alkaline waters. The growth of open reedswamp rooted in the basal clays, (F), was terminated by the development of a floating mat of bryophytes dominated successively by Acrocladium giganteum, Paludella squarrosa and Camptothecium nitens, with the rooted vegetation Schoenoplectus lacustris and Phragmites communis in all probability protruding through the mat. The sequence undoubtedly shows the effect of a floating carpet of mosses at least in part supported by a raft of Potentilla palustris and Menyanthes trifoliata, (C4), which gradually shut off the effects of the base-rich waters moving beneath. The development of mesotrophic conditions in the surface of the mat allowed colonization at least by the base-tolerant species of Sphagna, Sphagnum teres and S. plumulosum, (B2). The conditions within the mat appear to have been ideal for the preservation of plant remains corroborating the hypothesis that the effects of the moving (oxygenated) waters are cut down by the development of such a floating mat. The poorly preserved detritus mud, (D), could well represent deposition from the floating mat into the moving oxygenated waters beneath; the combined processes of growth of, and deposition from, the mat eventually filled the basin and shut off the effects of the main water movements through the lake system. However, there is no indication of the development of truly ombrotrophic (acid bog) conditions: the 'wet heath' vegetation dominated by Erica tetralix (B), developed at this stage and passed over to birch-dominated transition mire, (A4), after which the termination of the hydrosere was birch-dominated mire forest, (A, 2 and ), with a high but fluctuating water table (probably fed by run-off and seepage from the edge of the basin), which allowed the continued growth of peat and the persistence of mire species such as Carex rostrata and Phragmites communis. After peat growth in the basin terminated the site was sealed by downwash soils probably correlated with the clearance of the adjacent mineral ground.

10 4^ D. J. BELLAMY e^ a/. Pollen analysis {G.R.M. and.g.s.) Sampling details (for analysis procedure and pollen diagrams see Appendix). Samples were taken at io cm intervals from the monolith whose stratigraphy was described in the previous section. Zones represented (see Figs, 7 and 8). The basal pollen spectra dominated by Pinus, Betula and high NAP frequencies (though not nearly as many types as at Romaldkirk) suggest that they represent zone, and the end of the zone is drawn where the NAP types diminish. The rest of the diagram shows the immigration of trees from zone V onwards and the expansion of Almis and Tilia mark the beginning of zone Vila. The spectra do not provide sufficient evidence for the subdivision of zone V. The hydrosere. As at Romaldkirk, no distinct indication of succession is given by the pollen. The clearest correlation with the stratigraphy is at the cm level where the Camptotheciuni and Sphagnum peats exhibit high peaks of Sphagnum spores, and Ericaceae pollen, and also Filicales spores which in this context are probably attributable to a species such as Thelyteris palustris. At the very top of the deposit the drying out is accompanied by a very large increase in Gramineae pollen. Forest development. The most noticeable feature is the predominance of Pinus and Betula pollen and the low values for Ouercus and Ulmus, which suggests considerable local over-representation by the former two species, together with Corylus: throughout the period of deposition the forest on the margins of the basin appears to have been dominated by trees typical of the early stages of the Post-glacial period. The only exception is at the top of the deposit where the unusual values for Tilia coupled with the eroded nature of the pollen in the peat allow an interpretation of oxidation and subsequent differential preservation of pollen types, Bryophytes in the deposit The abundance of Paludella squarrosa and Camptothecium nitens in the deposit, (literally many tons of each moss must have been removed by the excavators), poses the question as to reasons for the extinction of the former and the rarity of the latter in lowland Britain today. A tentative suggestion is that as they appear to occupy a specialized ecological niche marking the end of 'rich fen' and the beginning of 'acid bog' development, that this particular association would never have covered extensive areas. Furthermore such marginal areas of fenland would he extremely vulnerable to reclamation for agricultural purposes. Thus it is suggested that widespread drainage eradicated Paludella while Camptothecium, perhaps due to its persistence into the next stage of the succession, still exists in a few lowland sites in England today. t is interesting to note that Helodium blandowii, a fragment of which was found in the Paludella peat by J. Dickson (first Post-glacial record), had a similar distribution in Britain to Paludella but is now believed extinct through drainage. ACKNOWLEDGMENTS Our thanks are due to Dr, M. P. Kerney and Mr. D, Smith for identification of the mollusca. Dr. J, Dickson for information on Helodium blandowii, and to Dr. V. B. Proudfoot and Dr, J, Clutton-Brock for comments on the Bos bones. Dr. H, A, P, ngram and students of the Extra-Mural Department of the University of Durham gave invaluable assistance with field-work. The interest and comments of Professor H. Godwin, F,R.S,, are gratefully acknowledged.

11 Quaternary deposits in the Tees basin 49 REFERENCES BARTLEY, D. D. (1962). The stratigraphy and pollen analysis of lake deposits near Tadcaster, Yorkshire. New PhytoL, 61, 277. BL.\CKBURN, K. B. (1952). The dating of a deposit containing an Elk skeleton found at Neasham near Darlington. Nezo PhytoL, 51, 64. JOHNSON, G. A. L. (196). The Geologv of ]\oor House. Monographs of the Nature Conservancy No. 2. H.M.S.O., London. WELLS, A. J. (19S7). The glaciation of the Teesdale-Swaledale watershed. Proc. Univ. Durham phil. Soc, 12, 82. APPENDX Samples were prepared by standard methods: simple KOH digestion for predominantly organic materials, HCl for the calcareous marls, and HF for siliceous deposits. At Romaldkirk the standard count for the Post-glacial horizons was 150 AP and for the Lateglacial period 250 total pollen. At Burtree Lane a standard count of 150 AP was used but low pollen frequencies precluded the attainment of this total in the lower samples.

12 440 D. J. BELLAMY et al. c^ 0^ O c^ c- C c- c- O c- C c- c- c (7- o a- (.- c- c- 1- o O CT c^ o- c c- C' c> o o-o c Cv c~ c- c- c- G- C- c- G- D c- c c- 7- c- c- c- o a O' (T (? u- C G- C O G- o C- G- c- c- G- (? o c- c- t? c- c '

13 Quaternary deposits in the Tees basin 441 Q Filicales ^ o Polypodium r ^4- + -f^ - ^, Z] 2 Cladium J2 Typha latifolia Myriophyllum Z\ 2 Nymphaea Z\ Potamogeton X Zi u^ Urtica = T) Umbelliferae JO Rosaceae -'*'-+-f- + ~ \ ^ J^ Ranuncutaceae -^ His Filipendula ~]o Ligultflorae 1 oj : Tubuliflorae *-' j2 Chenopodiaceae J o ij Caryophyllaceae g Artemisia ' a m Cyperaceae o so o Gramineae o Empetrum ^ Vaccinium

14 442 D. J. BELLAMY 0 40 BO Betula Pinus Ulmus Tilia Anus Salix Quercus 100 Corylotd Tree 8. shrub pollen/ pollen Fig. 7. Burtree Lane: tree pollen as percentages of total tree pollen. Zonation according to the customary British scheme. V m Fig. 8. Burtree Lane: non-tree pollen as percentages of total tree pollen. + + n n i! f c ^ 5? E H " '

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