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1 DE PART MENT OF CON SER VA TION Maine Geological Survey Rob ert G. Marv in ney, State Ge olo gist OPEN- FILE NO Ti tle: Author: Sur fic ial Ge ol ogy of the Lis bon Falls North 7.5 Quad ran gle, An droscog gin, Ken ne bec, and Sa gada hoc Coun ties, Maine Tho mas K. Weddle Date: 2001 Financial Support: Fund ing for the prepa ra tion of this re port was pro vided in part by the U.S. Geo logi cal Sur vey STATE MAP Pro gram, Co op era tive Agree ment No. 98HQAG2052. As so ci ated Maps: Sur fic ial ge ol ogy of the Lis bon Falls North quad ran gle, Open- File 99-9 Sur fic ial ma te ri als of the Lis bon Falls North quad ran gle, Open- File Contents: 8 p. re port

2 Maine Geo logi cal Sur vey Open- File Surficial Ge ol ogy of the Lis bon Falls North 7.5 Quad ran gle, Androscoggin, Kennebec, and Sagadahoc Coun ties, Maine Tho mas K. Wed dle Maine Geo logi cal Sur vey 22 State House Sta tion Augusta, Maine IN TRO DUC TION Sur fic ial map ping in the Lis bon Falls North 7.5 quad ran - gle was con ducted dur ing 1998 as part of the Maine Geo logi cal Sur vey s ba sic geo logic map ping pro gram, funded in part by the U.S. Geo logi cal Survey STATEMAP pro gram. The pur pose of this pro gram is to pro vide de tailed geo logic in for ma tion for use by the gen eral pub lic; mu nici pal, state, and fed eral agen cies; and for fun da men tal back ground in for ma tion for site- specific stud - ies. A sur fic ial geo logic map (Wed dle and oth ers, 1999) and a sur fic ial materials map (Wed dle and oth ers, 1999), both at 1:24,000 scale, have been com piled. The ma te ri als map shows the thick ness and com po si tion of sur face ma te ri als at points where sur face and sub sur face ob ser va tions were made. The geo - logic map shows the dis tri bu tion of geo logi cal units and fea tures that rec ord the geo logi cal his tory of the quad ran gle. This re port describes the sur fic ial de pos its mapped in the quad ran gle and pres ents the gla cial and post gla cial his tory of the quad ran gle. PRE VI OUS WORK AND AC KNOWL EDG MENTS Early de scrip tions of the sur fic ial ge ol ogy in the study area are found in Stone (1899) and Leavitt and Perkins (1935). A re - gional over view of the gla cial ge ol ogy of south west ern Maine can be un der stood by read ing Bloom (1960, 1963), Stuiver and Borns (1975), Smith (1982, 1985), Thomp son (1982, 1987), Thomp son and Borns (1985a), Thomp son and oth ers (1989), Smith and Hunter (1989), Retelle and Bither (1989), Kel ley and oth ers (1992), Wed dle and oth ers (1993), and Wed dle and Re - telle (1995). Soils in the quad ran gle were mapped by McEwen (1970) and Hed strom (1974). The sur fic ial ge ol ogy of the Lis bon Falls North quad ran gle was mapped pre vi ously at re con nais sance level by Bloom (1960) and Smith and Thomp son (1980). Other mod ern work in - cor po rat ing sur fic ial ge ol ogy in the study area in cludes Prescott (1979, 1980) and Tep per and oth ers (1985). Ber no ta vicz (1994) mapped a por tion of the quad ran gle as part of a Sen ior The sis at Bates Col lege, Lewiston, Maine. Wet lands map ping of the quad ran gle is pub lished by the U.S. De part ment of the In te rior Na tional Wet lands In ven tory. Sources of ma te ri als in for ma tion in the quad ran gle in clude bor ing logs along the Maine Turn pike and Interstate- 95, and other roads and bridge bor ings cour tesy of the Maine Turnpike Author ity and the Maine De part ment of Trans por ta tion (MDOT), and in MDOT un pub lished ma te ri als in ven tory maps, which de scribe many aban doned gravel pits that pro vided con - struction material for Interstate 95. The Maine Geo logi cal Sur - vey s (MGS) bed rock well da ta base in ven tory also pro vided depth to bed rock in for ma tion. (Note: the lo ca tion of wells in the MGS well in ven tory is based on tax lot map lo ca tions and not nec es sar ily on field ob ser va tions.) Nu mer ous gravel pit op era - tors and pri vate land own ers al lowed per mis sion to ac cess their prop erty. LO CA TION, TO POG RA PHY, AND DRAIN AGE The Lis bon Falls North 7.5 quad ran gle is lo cated just in - land from the Maine coast be tween 44 o 00'00" and 44 o 07'30"N latitude, and 70 o 00'00" and 70 o 07'30" W lon gi tude (Fig ure 1). It com prises parts of An droscog gin, Ken ne bec, and Sa gada hoc Coun ties, and parts of the com mu ni ties of Bow doin, Dur ham, Lewiston, Lis bon, Litchfield, Sabattus, and Top sham. Ele va - tions within the quad ran gle range from about 100 feet above sea level (asl) in the An droscog gin River val ley to over 630 feet asl in the northeastern cor ner of the quad ran gle. The quad ran gle has moderate relief, with maxi mum re lief of 530 feet be tween the An droscog gin River in the southwest and Whitten Hill in the north east. The ma jor drain age in the quad ran gle is by tributaries of the An droscog gin River, which makes a bend into the south east - ern part of quad ran gle and ex its there as well. The west ern half of the quad ran gle is drained by the Sabattus River and its tribu - 1

3 T. K. Weddle Fig ure 1. Lo ca tion map show ing the Lis bon Falls North 7.5' quad ran gle. tar ies, Max well Brook, Barker Brook, and No Name Brook. Drain age in the east ern half of the quad ran gle is by the Lit tle River and its tribu tar ies, Fisher Stream, Pring ton Brook, Gillespie Brook, Pot ter Brook, and Dearing Brook. BED ROCK GE OL OGY Bed rock in the quad ran gle is chiefly com prised of feld - spathic biotite grano fels mapped by Hussey (1983) as the Vas - sal boro For ma tion. The north west ern cor ner and a part of the north east ern cor ner of the quad ran gle have schists and grano fels mapped by Hussey (1983) as the Smalls Falls For ma tion, the Waterville For ma tion, and the San ger ville Formation. More in - for ma tion on the bed rock ge ol ogy of the re gion can be found in Hussey (1988, 1989). SUR FIC IAL GE OL OGY Bed rock and Thin- Drift Ar eas Gray ar eas on the map rep re sent bed rock where it crops out. Much of the north east ern part of the quad ran gle is mapped as thin drift (Ptd) where sur fic ial ma te rial over bed rock is less than 10 feet thick. In di vid ual out crops in these ar eas are not al - ways in di cated on the map. The lithologies of the sur fic ial de - pos its most of ten found in thin- drift ar eas may be till, ma rine de pos its, glaciomarine de pos its, or near shore de pos its. Till Till (Pt) is found at some sur face lo cali ties and re ported in sub sur face test bor ings. It is com monly a loose to com pact, gray 2

4 Surficial Geology of the Lisbon Falls North Quadrangle, Maine to ol ive gray, peb bly, silty, sandy, poorly sorted de posit (diamicton) of ten found over ly ing bed rock. Stratified-Drift Ice-Marginal Deposits Ice- contact strati fied drift de posts (Pgi). Sand and gravel de pos ited against rem nant masses of gla cial ice is rec og nized by the coarse- grained tex ture of its de pos its, and the ir regu lar, hum - mocky to pog ra phy usu ally as so ci ated with melt ing ice masses. It is found in one area in the high land of the north east ern cor ner of the quad ran gle. End mo raines (Pem), sub ma rine out wash fans (Pmf) and gla cioma rine del tas (Pmd). Certain ice-marginal deposits in Maine have been termed strati fied end mo raines be cause of their geo mor pho logic and sedi men to logic char ac ter (Ash ley and oth - ers, 1991). They are lin ear lo bate ridges, com prised of icetunnel de pos its (es kers), sub ma rine fans, del tas, and as so ci ated ice- proximal diamicton de pos its, and may con tain de for ma tion struc tures due to ice- marginal push or over rid ing. The location of these de pos its is con trolled by gla ci ol ogy and gla cial hy drol - ogy as well as to pog ra phy (Gus tavson and Boothroyd, 1987; Ash ley and oth ers, 1991; Cros sen, 1991; War ren and Ash ley, 1994). Sub gla cial or englacial drain age fol lowed the presentday val leys and where the ice mar gin was slowed in its re treat, there was time to build rela tively large de pos its. The in ter nal struc ture and com po si tion of simi lar fea tures else where in Maine has been de scribed in de tail by Smith and Hunter (1989), Retelle and Bither (1989), and Ash ley and oth ers (1991). The end mo - raines are most likely com plexes of sub ma rine fans com prised of subaque ous out wash, or they may be wash board or DeGeer mo raines (Sug den and John, 1988; Lundqvist, 1981), but be - cause of lack of ex po sure are here only termed end mo raines. These ice- front de pos its are gen er ally par al lel to the former mar - gin of the re treat ing ice sheet (Ash ley and oth ers, 1991), and there fore can be used to trace ice- marginal po si tions dur ing de - glaciation. End moraines (Pem) are com mon in the quad ran gle. More mo raines are proba bly pres ent in the area, but may be bur ied by over ly ing glaciomarine de pos its. In gen eral, the mo raines have an east/north east-west/south west trend (azi muth range 60 o - 90 o ). The mo raines are com monly as so ci ated with sub ma rine fan de - pos its. These mo raines are small to mod er ately large, usu ally oc - cur ring in clus ters, not more than feet high, feet wide, and feet in length. The curvilinear orientation of the mo raines re flect the im por tance of up land pin ning po si - tions of the ice mar gin. Dur ing its re treat, the gla cier mar gin was retarded by up lands, whereas in ad ja cent low lands the ice front re treated some what more rap idly than on the up land. Good ex - am ples of mo raines are found in the area ad ja cent to and be tween Pot ter Brook and Fisher Brook. Sub ma rine outwash- fan (Pmf) de pos its are pres ent in sev - eral ar eas in the quad ran gle, es pe cially in the Sabattus River and Puring ton Brook val leys. These se ries of fans re flect the trend of a meltwater drain age sys tem in the gla cier. In both areas, the fans iden tify ice- marginal po si tions where the mar gin remained long enough for the fans to form. Later, as the ice- margin re treated to a new po si tion to the north, dis tal gla cial de pos its from the more north erly po si tion par tially bur ied the ice- marginal de posits to the south. The val ley fans are trace able along trend to other strati fied drift de pos its to the north on the Lis bon Falls quad ran - gle, and be yond onto ad ja cent quad ran gles as part of an extensive esker sys tem in west ern Maine (Thompson and Borns, 1985b). Two glaciomarine del tas (Pmd) are pres ent in the quad ran - gle. At the north end of the Sabattus River val ley, ad ja cent to Sabattus Pond, is the Pleas ant Hill Delta (Thomp son and oth ers, 1989). This delta is char ac ter is tic of many ice- contact del tas with its steep north ward dip ping ice- contact slope, lo bate kidney- shaped form, and ice- block de pres sions (ket tles) on its sur face. On its northen edge, a trace able ridge (es ker) along Pleas ant Hill Road is pres ent, and rep re sents the po si tion of an ice tun nel at or near the ice mar gin, where sedi ment ema nated from the tun nel to build the delta (Retelle and Wed dle, 2001). The other delta in the quad ran gle is the Puring ton Brook delta (Kettlebottom Road delta of Thomp son and oth ers, 1989). This delta is not an ice- contact de posit, but was formed at some dis tance from the ice mar gin. It is an ex am ple of a leeside delta (Thomp son and oth ers, 1989), so- called be cause they are found on the lee sides (gen er ally to the south) of ridges or ranges of hills that ex tended above the ocean sur face dur ing the ma rine sub mer gence. Here the maxi mum ma rine limit of sub mer gence is ap proxi mately 300 feet above sea level. Ice- contact de pos its are found far ther north ad ja cent to Kettlebottom Road and which are above the ma rine limit mark the ap proxi mate po si tion of the ice mar gin that fed the sediment- laden meltwater dis charge to the ocean to form the Puring ton Brook delta. Presump scot Formation Glaciomarine mud (Pp) in the south ern Maine re gion has been named the Pre sump scot For ma tion by Bloom (1960). The silt and clay of this unit oc cu pies most of the val leys in the study area. Sub sur face data and sur face ex po sures show that the unit di rectly over lies bed rock, till, fans, and end mo raines, and can be in ter bed ded with subaque ous out wash. It can be mas sive or lay - ered, con tain ing out sized clasts, and in places is fossiliferous. It has a blue- gray color unweathered, and an olive- gray color when weath ered. Frac ture sur faces in the weath ered Pre sump scot For - ma tion com monly are stained by iron- manganese oxides. The Pre sump scot For ma tion was de pos ited by gla cio flu vial activity dis charg ing ma te rial into the gla cial sea. Based on as so ci ated fos sil as sem blages, it is con sid ered a late Pleis to cene cold- water ma rine unit (Bloom, 1960). It can be stratigraphically re lated to ice- marginal de pos its, hence in its old est stratigraphic po si tion, it is also glaciomarine in ori gin. How ever, up sec tion at some point it be comes ex clu sively ma rine when it is no longer di rectly linked with gla cial ice in con tact with the ocean. A good ex po - sure rep re sent ing both the ice- proximal and ice-distal/basinal 3

5 T. K. Weddle na ture of the Pre sum sump scot For ma tion is found at the gravel pits in the Sabattus River fans about 0.5 miles south of Crowley Road on the west side of the Sabattus River val ley A sandy fa cies of the Pre sump scot For ma tion found over - ly ing the fine- grained fa cies has been de scribed (Smith, 1982, 1985; Thomp son, 1982, 1987). The con tact be tween the fa cies is re ported to be sharp or gra da tional, and the ori gin of the sandy fa cies ap pears to be as so ci ated with shoal ing dur ing the re gres - sion of the sea. It also has been de scribed as a gra da tional fa cies be tween the clay and the deltaic/fan fa cies (Ko teff, 1991), al - though this in ter pre ta tion places it stratigraphically be low the re - gres sive de pos its. In ter bed ded sand and clayey silt over ly ing mas sive Pre - sump scot For ma tion mud is pres ent in the Lis bon Falls North quad ran gle, as well as at lo ca tions in ad ja cent quad ran gles and in test- boring re ports in the area. How ever, the in for mal term sandy Pre sump scot For ma tion as used by oth ers as a map pa ble unit (e.g., Wed dle, 1987; Smith, 1999; Hildreth, 1999; Hunter, 1999) is not used in the Lis bon Falls North quad ran gle. This unit has been as so ci ated by these work ers with ma rine re gres sive de - pos its, stratigraphically above the mas sive mud of the Pre sump - scot For ma tion (sensu stricto). In some in stances, mas sive sand of flu vial ori gin and un con forma bly over ly ing the Pre sump scot For ma tion has been mapped as sandy Pre sump scot Formation (Wed dle, 1987; Smith, 1977). In the Lis bon Falls North quad - ran gle, the term near shore de posit (Pmn) is used for shal low wa - ter or wave re worked de pos its as so ci ated with ma rine trans gres sion and re gres sion (see be low). Dis tal sand re lated to subaque ous glaciomarine fan or delta depo si tion and which is in - ter bed ded with the Pre sump scot For ma tion is con sid ered part of the Pre sump scot For ma tion and is mapped as such (Pp). Near shore and Shoreline Deposits and Pleistocene Alluvium Sub se quent to the depo si tion of the Pre sump scot For ma - tion, ex ist ing units were re worked by the ma rine re gres sion, and near shore de pos its (Pmn) were laid down. Wa ter depth and rela - tive sea level in the re gion was con trolled by glacio-isostatic re - bound and eustatic sea level changes, and dur ing the late Pleis to cene in this area, isostatic con di tions were preva lent (Stuiver and Borns, 1975; Belknap and oth ers, 1987; Kel ley and oth ers, 1992). These de pos its are found in many lo ca tions, as a thin to thick ve neer of sedi ments rang ing in grain size from coarse grav els to mas sive mud; how ever, most are not shown on the map be cause they are not thick enough to ob scure the un der - ly ing units. These de pos its are the re sult of wave ac tiv ity in late Pleistocene near shore or shallow- marine en vi ron ments (sub - tidal, la goonal, and beach en vi ron ments of Retelle and Bither, 1989), and com po si tion ally re flect the un der ly ing par ent ma te - rial. How ever, they do not necessarily have a shore line mor phol - ogy. Thick near shore de pos its (Pmn) shown on the map are found flank ing the slopes of hill sides and del tas, and in broad low ar eas in the Sabattus River and Lit tle River val leys. Also, nearshore de pos its of ten are associated with thin-drift areas. Pleistocene al luvium de pos its (Pa) are found as ter races along the An droscog gin River val ley at ele va tions above the mod ern flood plain. Where ex posed they con sist of trough- cross bed ded sand and gravel, char ac ter is tic of braided- stream de pos - its (Wed dle, 1997). Holocene Deposits Eolian de pos its are com mon in the area. How ever, they are not shown on the map be cause they are not thick enough in most ar eas to mask the un der ly ing units. Holo cene de pos its have been mapped as fresh wa ter wet lands (Hw) and stream al lu vium (Ha). GLA CIAL AND POST GLA CIAL HIS TORY Qua ter nary Ge ol ogy The gla cial de pos its in the Lis bon Falls North quad ran gle were de rived from the last ice sheet which cov ered Maine, the late Wis consi nan age Lau ren tide Ice Sheet, which reached its maxi mum in New Eng land about 25,000 yr B.P. (Stone, 1995). Glacial striations and streamlined hill orientations reflect ice flow through the quad ran gle and generally vary within 10 o - 15 o of 180 o, al though one lo ca tion on an up land in the north west cor - ner of the quad ran gle has a stria tion trend of 143 o. In the ad ja cent North Pownal quad ran gle (Marv in ney, 1999) and Ray mond quad ran gle (Retelle,1997), sev eral up land stria tions trend ing near 140 o are pres ent. At one lo ca tion in the north west part of the quad ran gle, cross-cutting stria tions are found where a south west trend (208 o ) cuts across an older southeast trend (163 o ). In other nearby quad ran gles where multiple- striation lo cali ties are found, southeast- trending stria tions are more com monly older than the south- and south west-tren ding stria tions (Wed dle, 1997, 1999; Maine Geo logi cal Sur vey, un pub lished data). Good examples of streamlined hills in the Lis bon Falls North quad ran - gle in clude Lis bon Ridge, Whitten Hill, and the hill whose north end be gins be tween Spear Cemetery and Loon Pond. Ice re ces sion from the Gulf of Maine proba bly be gan some time around 17,000 yr B.P. (Smith, 1985; Smith and Hunter, 1989). Ra dio car bon dates in the im me di ate area pro vide mini mum dates for the deglaciation of the re gion (Stuiver and Borns, 1975; Smith, 1985). A pre vi ously re ported age of 14,045 ± 95 yr B.P. (Wed dle, 1999) from a Port lan dia arctica shell in glaciomarine de pos its in Freeport was reanalysed be cause its del 13 C value (-9.1 o/oo) is well be yond the sug gested mean del 13 C value for ma rine car bon ate (0 ± 2 o/oo; CALIB 4.0 Manual, Ta ble 1; dio car bon.org/). A new age es ti - mate on an other Port lan dia from the same de pos its is 13,000 ± 55 yr B.P. (OS ; del 13 C o/oo. How ever, an age analysis on Mytilus edu lis shells found in mud overlain by near - shore deposits in Phipps burg (13,600 ± 380 yr B.P. (GX ; Wed dle and Retelle, 1998; Retelle and Wed dle, 2001) pro vides a mini mal date for deglaciation in the Casco Bay re gion. Degla - 4

6 Surficial Geology of the Lisbon Falls North Quadrangle, Maine Fig ure 2. Sche matic chart show ing cor re la tion of geo logic units in the Lis bon Falls North 7.5' quad ran gle. End mo raine (Pem) and ma rine fan (Pmf) units are read from left to right and bot tom to top, cor re spond ing to west to east and south to north, re spec tively, on the sur fic ial ge ol ogy map. Age es ti mates are in un cor rected ra dio car bon years. ciation proba bly oc curred sev eral hun dred years ear lier, most likely closer to 14,000 ra dio car bon years B.P. Dur ing the re treat of the gla cier, the ocean was in con tact with the ice mar gin. Pleis to cene sea level at the time of deglacia - tion in the study area was ap proxi mately 320 feet above mod ern sea level (Thomp son and oth ers, 1989). The foot flattopped sur face of the Pleas ant Hill delta south east of Sabattus Pond ap proxi mates this high synglacial sea- level stand. As the ice mar gin passed through the Lis bon Falls North quad ran gle, all the present- day land be low about 320 feet was com pletely sub - merged. The ar eas above 320 feet in the quad ran gle were is lands and those ar eas just be low that ele va tion were shoals. The tidal range in the Gulf of Maine dur ing this time was less than a me ter (Scott and Green burg, 1983). The dis tri bu tion and ori en ta tion of ice- marginal sub ma rine and deltaic de pos its also re flects the flow of ice in di cated by the stria tion di rec tion data. The mo raines and glaciomarine de posits oc cur along a trend near per pen dicu lar to the stria tion di rec tions and in di cate that the gla cier with drew from the mod ern coastal zone and pro gres sively re treated in land as a near east- west trend ing, ac tive ice sheet grounded in a glaciomarine en vi ron - ment. The de pos its are regu larly younger from south to north, re flect ing the sys tem atic re treat of the ice in the quad ran gle. The correlations and ap proxi mate age of the de pos its are sche mati - cally rep re sented on Fig ure 2. As the ice re treated, it was pinned on bed rock high lands and was grounded in the in ter ven ing low ar eas as evi denced by shape and lo ca tion of the mo raines and ice- marginal po si tions. At the ice- marginal po si tions, end mo raines and fans com prised of subaque ous out wash rep re sent depo si tion by ice- tunnel or stream dis charge, or by ice- push at the mar gin (Ash ley and oth - ers, 1991). With rea son able cor re la tion, these de pos its can be 5

7 T. K. Weddle used to re con struct the ori en ta tion and rela tive po si tion of the ice mar gin in time dur ing deglaciation. These land forms re flect the shape of the ice mar gin dur ing deglaciation, which ap pears to have been slightly lo bate down val ley. The ice- marginal po si tions in ferred on the map are found in the low lands of the Sabattus River and Lit tle River. These two ar eas are sepa rated by cen tral high lands, and bor dered by high - lands to the east and west. The old est ice- margin po si tions iden - tified are rep re sented by the Lit tle Falls (Pemlf) and Hu don Road (Pemh) end mo raines lo cated at the south west cor ner of the quad ran gle. North of these de pos its are nu mer ous un named small mo raines, which rep re sent mi nor stillstands or readvances of the ice mar gin. As the mar gin re treated north to Lis bon Ridge, it was im peded by and pinned on the ridge long enough for the Whites Hill (Pmfwh) and Hig gins Cor ner (Pmfhc) fans to be de - pos ited. The mo raine com plexes north of Lis bon Ridge, from west to east the Sabattus River (Pemsr), Ridge Road (Pemr), Webster Cor ner (Pemwc), and Fisher Brook (Pemfb) end mo - raine com plexes rep re sent the re treat of the mar gin through the cen tral low- lying area in the quad ran gle. The lo bate na ture of the ice mar gin is well rep re sented by the ori en ta tion of these mo - raines. To the east, the re treat of the mar gin is relected by the depo si tion of the West Bow doin fan (Pmfwb) and the Kettlebot - tom fan (Pmfk), so called be cause of a large kettlehole in its cen - ter mark ing the po si tion of a melted ice block. To day, half of the kettlehole is mined away by a gravel pit op era tion. On the west side of the quad ran gle, the Sabattus River fans are a good ex am - ple of a de posit known as a beaded es ker (Sollid and Carlson, 1984; Caldwell and oth ers, 1985; War ren and Ash ley, 1994). In - stead of a long ridge (es ker) form ing from depo si tion within an ice tun nel, the mar gin of the gla cier re treats rap idly as ma te rial from the ice- tunnel is de pos ited at the mar gin as a se ries of seg - mented fans, pos si bly rep re sent ing an nual re treat of the ice mar - gin. In the Lis bon Falls North quad ran gle, the Sabattus River fans sepa rate two larger de pos its, the Whites Hill fan and the Pleas ant Hill delta. These larger de pos its may rep re sent a pe riod when the ice mar gin was at a rela tive stillstand as com pared with the smaller in ter ven ing fans. Al ter na tively, the larger de pos its could re flect an in crease in meltwater dis charge from the ice tun - nel. The Pleas ant Hill delta marks the most promi nent ice mar - ginal po si tion in the north ern por tion of the quad ran gle. Im me - di ately north of the delta, more small fans are found, the Sabattus Pond fans (Pemsb). These fans con tinue north in this low land into the Mon mouth quad ran gle in the same beaded man ner as the Sabattus River fans to the south, and ter mi nate at an other large de posit, the Marr Point delta (cf., Fig ure 7 in Retelle and Wed dle, 2001). The ice- marginal po si tion as so ci ated with the Pleas ant Hill delta is not read ily traced across the north east ern part of the quad ran gle. North of the Kettlebottom fan, the Puring ton Brook delta is found at a slightly lower ele va tion than the Pleas ant Hill delta. As men tioned pre vi ously, it is a lee- side delta formed at some dis tance from the ice mar gin, and thus does not im me di - ately mark an ice- marginal po si tion. This delta may have bur ied mo raines and glaciomarine fans as it pro graded sea ward dur ing its for ma tion. Its sur face is dis sected by meltwater chan nels that incised the delta top as rela tive sea level fell be cause of re bound of the land by the re moval of the weight of the ice mass by melt - ing. The ice- contact de pos its found north of the Puring ton Brook delta most likely rep re sent the ice- marginal source of the meltwater that pro vided the sedi ment to form the delta. The Pre sump scot For ma tion (Pp) was de pos ited coe val with the ice- marginal de pos its. These sedi ments set tled out both near and be yond the mar gin of the ice and can be found interfinger ing with the fan sedi ments or as a blan ket drap ing older de - pos its. Marine fos sils in the Pre sump scot For ma tion are found at sev eral lo ca tions in the quad ran gle, and some of these have yielded ra dio car bon age- dates. Lo cal up lift due to isostatic re bound oc curred dur ing de - glaciation and re sulted in re gres sion of the gla cial sea. An un - cor rected ra dio car bon date of 13,300 ± 50 yr B.P. on Mytilus edu lis from near shore de pos its in a pit at ap proxi mately 200 feet (61 m) asl in the ad ja cent North Pownal quad ran gle to the east rec ords the ear li est date for ma rine re gres sion in the immediate area. Dur ing this rela tive fall of sea level, near shore and shore - line de pos its were formed. Pleis to cene near shore de pos its are found along glaciomarine delta flanks and fronts, as well as over glaciomarine mud over a con sid er able area in the quad rangle, and wave- cut ter races have been re ported on the delta slopes (Cros sen, 1984, 1991). The tim ing of re gres sion in the Lis bon Falls North quad - ran gle is not very well known. If as in the ad ja cent quad ran gles, near shore de pos its were form ing at ap proxi mately 200 ft asl about 13,300 ra dio car bon yr B.P., and had fallen to about 150 ft by ap proxi mately 12,800 (Retelle and Wed dle, 2001), an es ti - mate of rela tive sea- level fall in the re gion can be de ter mined and is about 8.3 ft / 100 yr (2.5 m / 100 yr). The low est ele va tion in the Lis bon Falls North quad ran gle is at ap proxi mately 100 ft, so based on the es ti mated emer gence rate above and as sum ing a near steady rela tive sea- level fall, the ma rine re gres sion would have been com plete in the quadran gle by around 12,200 ra dio - car bon yr B.P. How ever, evi dence ex ists for pe ri ods of rela tive stillstands dur ing the ma rine re gres sion in the re gion, hence the above es ti mate of when ma rine re gres sion in the quad ran gle was com plete is tentative (Wed dle and Retelle, 1995; Retelle and Wed dle, 2001). As relative sea-level reached its low est level around 10,500 ra dio car bon yr B.P. well off shore of the mod ern coast line (Kel - ley and oth ers, 1992; Barn hardt and oth ers, 1995), pres ent day drain age be came es tab lished. Deep ero sion in the glaciomarine mud, such as the gul lies now found in the Lit tle River val ley also formed dur ing this time. Many of these gul lies have down cut to bed rock, and most of the gul lies are floored by wet land de pos its; how ever, a thin ve neer of Holo cene al lu vium is pres ent along stretches in some val leys. Most gul lies have steep sidewalls bound ing a broad, flat- floored val ley, in which streamflow dur - ing floods can be dra matic. Slump ing and ero sion of the gully sidewalls dur ing floods is a mod ern pro cess; how ever, most of 6

8 Surficial Geology of the Lisbon Falls North Quadrangle, Maine the gully ero sion proba bly oc curred dur ing late gla cial time prior to vege ta tion. Af ter reach ing its low est level, sea level be gan to rise resulting in ag gra da tion within river chan nels and drown ing of the chan nels near the mod ern coast to form es tu ar ies. REFERENCES CITED Ash ley, G. M., Boothroyd, J. C., and Borns, H. W., Jr., 1991, Sedi men tol ogy of late Pleis to cene (Laurentide) deglacial-phase de pos its, east ern Maine; an ex am ple of a tem per ate ma rine grounded ice- sheet mar gin, in An der son, J. B., and Ash ley, G. M. (edi tors), Gla cial ma rine sedi men ta tion; paleo - climatic significance: Geological Society of America, Special Paper 261, p Bernotavicz, A. A., 1994, Gla cial and post gla cial his tory of the Sabat tus River val ley, Sabat tus, Maine: B. A. the sis, Bates Col lege, Lewis ton, Maine, 141 p. Barn hardt, W. A., Gehrels, W. R., Belk nap, D. F., and Kel ley, J. 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9 T. K. Weddle Stuiver, M., and Borns, H. W., Jr., 1975, Late Qua ter nary ma rine in va sion in Maine; its chro nol ogy and as so ci ated crustal move ment: Geo logi cal So - ci ety of Amer ica, Bul le tin, v. 86, p Sug den, D. E., and John, B. S., 1988, Gla ciers and land scape, a geo mor pho logi - cal ap proach: Ed ward Ar nold, Lon don, 376 p. Tep per, D. H., Wil liams, J. S., Tol man, A. L., and Pres cott, G. C., 1985, Hy dro - ge ol ogy and wa ter qual ity of sig nifi cant sand and gravel aq ui fers in parts of An droscog gin, Cum ber land, Frank lin, Kennebec, Lin coln, Ox ford, Sa gada hoc, and Somerset Coun ties, Maine: Maine Geo logi cal Sur vey Open- File Report 85-82a, 106 p. Thomp son, W. B., 1982, Re ces sion of the late Wis consi nan ice sheet in coastal Maine, in Larson, G. J. and Stone, B. D. (edi tors), Late Wis consi nan gla - cia tion of New Eng land: Kendall/Hunt Pub lish ing Co., Du buque, Iowa, p Thomp son, W. B., 1987, The Pre sump scot For ma tion in south west ern Maine, in An drews, D. W., Thomp son, W. B., San ford, T. C., and No vak, I. D. (edi - tors), Geo logic and geotechnical characteristics of the Pre sump scot For - ma tion, Maine s gla cioma rine clay : un pub lished con fer ence pro ceed ings, March 20, 1987, at Uni ver sity of Maine, Augusta: Maine Geo logi cal Sur vey, 22 p., (each pa per pagi nated sepa rately). Thomp son, W. B., and Borns, H. W., Jr., 1985a, Till stra tigra phy and late Wis - consi nan deglaciation of south ern Maine: Geo gra phie phy sique et Qua - ternaire, v. 39, no. 2, p Thomp son, W. B., and Borns, H. W., Jr., 1985b, Sur fic ial geologic map of Maine: Maine Geo logi cal Sur vey, scale 1:500,000. Thomp son, W. B., Cros sen, K. J., Borns, H. W., Jr., and An der sen, B. G., 1989, Glaciomarine del tas of Maine and their re la tion to late Pleistocene- Holocene crustal move ments, in An der son, W. A., and Borns, H. W., Jr. (editors), Neotectonics of Maine: stud ies in seismicity, crustal warp ing, and sea- level change: Maine Geo logi cal Sur vey, Bul le tin 40, p War ren, W. P., and Ash ley, G. M., 1994, Ori gins of ice- contact strati fied ridges (es kers) of Ire land: Jour nal of Sedi men tary Re search, v. A64, p Wed dle, T. K., 1987, Re con nais sance sur fic ial ge ol ogy of the Nor ridge wock quad ran gle: Maine Geo logi cal Sur vey, Open- File Map 87-23, scale 1:62,500. Wed dle, T. K., 1997, Sur fic ial ge ol ogy of the Lis bon Falls South 7.5- minute quad ran gle, An droscog gin, Cum ber land, and Sa gada hoc Coun ties, Maine: Maine Geo logi cal Sur vey, Open-File Re port 97-64, 12 p. Wed dle, T. K., 1999, Sur fic ial ge ol ogy of the Freeport quad ran gle, Maine: Maine Geo logi cal Sur vey, Open- File Map 99-83, scale 1:24,000. Wed dle, T. K., Nor mand, A. E., and Bernotavicz, A. A.,1999, Sur fic ial ge ol ogy of the Lis bon Falls North quad ran gle, Maine: Maine Geo logi cal Sur vey, Open- File Map 99-9, scale 1:24,000. Wed dle, T. K., Nor mand, A. E., Bernotavicz, A. A., and Neil, C. D., 1999, Sur fic - ial ma te ri als of the Lis bon Falls North quad ran gle, Maine: Maine Geo - logi cal Sur vey, Open- File Map 99-10, scale 1:24,000. Wed dle, T. K., Koteff, C., Thomp son, W. B., Re telle, M. J., and Marv in ney, C. L., 1993, The late- glacial ma rine in va sion of coastal cen tral New Eng - land (north east ern Mas sa chu setts - south west ern Maine): its ups and downs, in Che ney, J. T., and Hep burn, J. C. (edi tors), Field trip guide - book for the north east ern United States, Geo logi cal So ci ety of Amer ica, An nual Meet ing, Bos ton, Mas sa chu setts, Vol. 1: Con tri bu tion No. 67, De part ment of Ge ol ogy and Ge og ra phy, Uni ver sity of Mas sa chu setts, Amherst, Chap ter I, 31 p. Wed dle, T. K., and Re telle, M. J., 1995, Glaciomarine de pos its of the Late Wis - consi nan Casco Bay Sublobe of the Lau ren tide Ice Sheet, in Hussey, A. M., II, and John ston, R. J. (edi tors), Guide book to Field Trips in south ern Maine and ad ja cent New Hamp shire: New Eng land In ter col le giate Geo - logi cal Con fer ence, 87th An nual Meet ing, Bruns wick, Maine, p Wed dle, T.K., and Re telle, M.J., 1998, Deglacial style and rela tive sea- level chro nology, Casco Bay low lands to White Moun tain foot hills, south - west ern Maine: Geo logi cal So ci ety of Amer ica Abstracts with Pro - grams, v. 30, n.1, p