Geological and Palynological Studies of Early Lake Erie Deposits C

Home , Early Lake Erie, Lake Whittlesey

Pub. No 15, Great Lakes es4cJi Pivisiou, The tiniversity of Michigan, 1966 • • _ • - Y , R R , , 4.4 TO ULL A . g t, -_____•_:_:::._ ...... / GEOLOGICAL AND PALYNOLOGICAL STUDIES OF EARLY LAKE ERIE DEPOSITS C. F. M. Lewis, T. W. Anderson, and A. A. Berti Geological Survey of Canada, Ottawa

Abstract. Coring and echo sounding of Lake Erie bottom sediments have indicated a thin lag concentrate of sand, in places with plant detritus, pelecypods, gastro- pods and other fossils, underlying Recent silty clay muds and overlying clay till or late-glacial lacustrine clays. Buried shallow pond organic sediments in the western basin and relict beach deposits, wave-cut terraces and intrabasinal discharge channels in the central basin, some of which are buried, all indicate former low water levels in central and western Lake Erie much below those at present. This evidence, combined with radiocarbon dates of 10,200 and 11,300 years B.P. on the organic material and in- formation from nearby regions, suggests that Early Lake Erie came into existence about 12,400 years ago, with water levels, 100 ft (30 m) lower than at present, at approximately 470 ft above sea level. From this stage lake levels rose rapidly as the outlet area at Buffalo, N.Y., was uplifted isostatically following deglaciation, and probably reached their present elevation 9,000 to 10,000 years ago. Examination of the cores indicated that pollen is sufficiently abundant and well preserved in the sediments for palynological studies. Pollen diagrams can be corre-. lated with one another, and with those outside of the Lake Erie basin. The presence of a legible pollen record indicates that sedimentation has been probably continuous and undisturbed at the sites investigated since low-level Early Lake Erie. Palynological studies support the geological evidence of a low lake stage and provide a means for dating and correlating sediment sequences which do not contain enough organic matter for radiocarbon analysis.

INTRODUCTION

Results of coring, echo sounding and SCUBA diving carried out from the research vessel C.C.G.S. PORTE DAUPHINE as part of a general study of the unconsolidated deposits in Lake Erie basin under the auspices of the Great Lakes Institute, University of Toronto, have suggested the existence of postglacial low level stages of Lake Erie. Sediment samples at depths up to 11 and 12 m below the lake bed were collected by piston cores with core tubes having an inside diameter of 4.9 cm fabricated from AX drill casing. Three piston cores were studied for pollen content by personnel of the Pleistocene Palynology Laboratory, Geological Survey of Canada, to provide supporting en- vironmental and chronological evidence for conclusions regarding low lake stages based on geological evidence. The objective of this paper is to present geological and palynological evidence of postglacial low-level lake stages in Lake Erie and to integrate the sequence of these stages with the known history of the lower Great Lakes region.

DESCRIPTION OF BOTTOM DEPOSITS

Figure 1 is a generalized map of Lake Erie bottom deposits prepared from results of sampling and echogram interpretation. Two major bottom deposit types were recognized: nearshore and ridge top areas where silty clay mud does not occur and offshore areas where mud does occur.

176 EARLY LAKE ERIE SEDIMENTS 177

82° 81° 80° 79 7 43 Portl Maitlan

oraln CLEVELAND BATHYMETRY AND BOTTOM MATERIALS

LEGEND CONTOUR INTERVAL 10 METRES

RECENT SOFT SILTY CLAY SEDIMENT...... !In DATUM: MEAN WATER LEVEL SAND, SAND VENEERED TILL OR GLACIO- 570 FEET ABOVE SEA LEVEL LACUSTRINE CLAY OR BEDROCK ...... (I GLD 1955) UNKNOWN ...... MILES 1244 • 0 25 50 75 100 I I I I I PISTON CORES 1 240 ...... • 0 40 80 120 160 2226 ...... 0 KILOMETRES

FIG. 1. Lake Erie, showing bottom materials, bathyrnetry and location of piston cores used for palynological studies and radiocarbon analysis.

In the nearshore areas and atop the Pelee-Lorain and Long Point-Erie ridges, clay till or dense glacio-lacustrine clay is usually overlain by a thin (few cm), patchy, rippled sand lag concentrate often with pebbles and detrital shell fragments. In places sand has accumulated to greater thicknesses and buried the clay surface. Bedrock is not exposed along the north shore of the central basin but outcrops along the shore of the eastern basin and is reported to be immediately offshore from much of the south shore of the central basin (Hartley 1961a). Bedrock commonly outcrops in the islands region of western Lake Erie. A soft, grey, silty clay mud occurs in all offshore areas. The surface of this mud is nearly level in the western (depth about 10 m) and central (depth between 20 and 24 m) areas of the lake. The eastern area alone is basin-shaped, reaching a maximum depth of 66 m off Long Point. Echo sounding and seismic reflection profiling have indicated mud thicknesses approaching 5 to 10 m, 20 to 25 m and 40 m in the medial regions of western, central, and eastern basins respectively. The mud deposits thin towards shore and reach zero thickness along the boundaries shown in Fig. 1. An examination of piston cores which penetrated the mud deposit where its thickness did not exceed 12 m revealed a nearly uniform mud section. The mud is a faintly laminated, soft, grey silty clay which in places contains pele- cypod, gastropod and ostracod shells, both entire and broken. The shells commonly occur with wood chips and plant debris as thin concentrations within or at the base of the mud. The material beneath the mud generally varies from basin to basin. Be- neath the mud in the northern half of the eastern basin is a zone (5 to 20 cm thick) of silt, fine sand and delicate shell fragments underlain by moderately dense, red laminated glacio-lacustrine clay. In the central basin, dense, red- dish grey clay till or glacio-lacustrine clay underlies the mud. Above depths of 178 LEWIS, ANDERSON, and BERTI

25 to 28 m, a thin zone of sorted and subrounded sand with pebbles and shell fragments overlies the dense clay. Below 25 to 28 m, the mud may directly overlie the clay or a thin horizon of shells may mark the contact; or the basal 10 to 50 cm of mud may be interstratified with sand. In the western basin the mud is siltier and is usually underlain by 5 to 20 cm of dark brown, spongy plant detritus. This detritus, occurring at depths ranging from 11 to 14 m below lake level and from 1 to 4 m below the sediment-water interface, is underlain by well sorted sand, dense clay till, or glacio-lacustrine clay or silty clay impregnated with plant detritus. The piston cores permitted the identification of a prominent subbottom reflection recorded on echograms of a Kelvin and Hughes MS26B Echosounder and a "Sparker" (seismic reflection profiler with electric discharge sound source) as the contact between the silty clay mud and the sand-veneered, dense clay till or glacio-lacustrine clay. A map showing the topography of the till and dense clay surface was prepared from the echograms (Fig. 2). Depth contours of this surface are considered reliable down to approximately 35 m in offshore areas. Below 35 m, reflections were sporadic and had to be interpo- lated. Near the base and edges where the overlying mud is admixed with sand, subbottom reflections are diffuse and in places absent. The salient features on this map are: (a) shallow basins in western Lake Erie; (b) a small basin northeast of Sandusky, Ohio, separated from (c) a large central basin by (d) a ridge between Pelee Point and Lorain, Ohio; (e) an incipient ridge between Erieau, Ont., and Cleveland, Ohio, constricting the central basin; (f) a broad ridge between the base of Long Point and Erie, Pa., partitioning the central and (g) the deep eastern basins. Note also the east-west trending channels at the southern termini of the Pelee-Lorain and Long Point-Erie ridges. Hartley (1960) has shown the Pelee Point-Lorain ridge to be composed of till and capped with sand and gravel. He states that the till surface in the associated

° 81 80° 79 4 2 Port 78 430 MaltIan BUFFALO Port S anl 4230

42°

41*30' CLEVELAND LAKE ERIE MAP SHOWING INFERRED TOPOGRAPHY OF PLEISTOCENE DEPOSITS DERIVED DEPTH CONTOURS IN------2 METRES APPROXIMATE FROM PISTON CORE AND ECHOGRAM - ASSUMED - ---2 DATA. MILES 0 25 50 75 100 DATUM: MEAN WATER LEVEL 570 FEET ABOVE SEA LEVEL (IGLD 1955). 0 40 80 120 160 KILOMETRES

FIG. 2. Lake Erie, showing topography of Early Lake Erie basin. Contours are drawn on the surface of glacial or glacio-lacustrine deposits. EARLY LAKE ERIE SEDIMENTS 179 channel descends to a depth of 106 ft (32 m). The northern and southern sections of the Erieau-Cleveland ridge are composed of till and are capped with sorted sand where the ridge descends beneath the mud surface. In the central and deepest portion, this ridge is composed of dense, glacio-lacustrine clay. The Long Point-Erie ridge is a broad rise 17-40 km wide, the western surface of which is mainly dense till veneered with a thin, rippled, sand lag concentrate at depths below 18 to 20 m, and the eastern surface of which is sand- covered at depths less than 18 m. A piston core located approximately 18 km northwest of Erie has shown the channel floor at the southern end of this ridge to be clay till at a depth of 29 m.

EVIDENCE OF LOW-LEVEL LAKE STAGES Long Point-Erie Ridge The western part of this ridge appears to be a wave-eroded clay till surface veneered with a sandy lag concentrate which slopes gently southwest- ward from the 18 to 20 m depth contour. Immediately east of this area and lying at shallower depths between 14 and 18 m, the ridge is composed of sand with thicknesses apparently exceeding 1 m (corer did not penetrate further). Deposition of the sand and erosion of the till surface (1) may be occurring together at the present time, (2) may have occurred at different times and by different processes in the past, or (3) may have occurred simultaneously in the past. Under possibility (1) the till surface would be eroded by present wave action driven from the west by prevailing winds which cause residual sand to migrate eastward toward the crest of the ridge. If this were true, one would expect the sand to be carried completely over the crest and dumped off the eastern flank creating an erosion surface on the ridge crest itself devoid of sand. The same objection may be raised against simultaneous sand deposition and erosion of the till surface by bottom currents. The Long Point-Erie ridge is a site of constriction in the lake between the eastern and central basins. One would expect currents resulting from basinal interchange of water to be strongest across the crest of the ridge causing erosion, and weakest lower down on the flanks of the ridge resulting in sand deposition. Under possibility (2) the till surface might have been eroded at an early date during times of excessive storm wave activity or when water levels were lower and the sand might have been deposited at a later date under different wave and/or current systems. Thus the sand might be a spit resulting from deposition on a previously eroded till surface by littoral currents flowing from shore bluffs to the northeast or northwest before Long Point was constructed, i.e. the sand might be a predecessor of Long Point. This is not very probable because there is no evidence of intermediate stages of spit development lying between this deposit and the present Long Point. Furthermore, the largest source of sand for such a spit lies in the shore bluffs to the west of Long Point and the most likely direction of spit development, controlled by prevailing westerly winds, is to the east parallel to the north shore, not towards the south. At the present time the patterns, durations, and velocities of currents in Lake Erie are largely unknown, and the mechanics of lake bed erosion and deposition by currents is understood even less. For the moment, the Long Point- Erie sand is most easily explained under possibility (3) as a relict beach deposit built in the past by a lake some 20 m lower than present Lake Erie. In this low-level lake, the largest storm waves likely came from the west because 180 LEWIS, ANDERSON, and BERTI the prevailing wind and greatest fetch both lay in that direction. These waves pounded against the western flank of the Long Point-Erie ridge where they cut a terrace across which the eroded sand was transported and finally laid down as a beach deposit along the ridge crest at lake level. The sand may have been further heaped up by wind action into dunes. Northern Central Basin The lake bed along the north shore, where it is not covered with Recent mud at present, is a smooth, gently southward dipping surface underlain by clay till or dense lacustrine clay and veneered with a thin, rippled, sandy lag concentrate. It is apparently a wave-eroded terrace. Various echogram profiles show this surface to extend beneath the present mud deposits to depths ranging between 21 and 37 m. A definite increase in slope of this surface was noted on two profiles at depths of 23.5 and 31 m. The echograms also showed that laminations(?) in the underlying glacio-lacustrine clays were truncated by the clay-mud surface at six locations ranging in depth between 22 m and 31 m and possibly at two other locations at depths of 32 m and 35 m. The thin, sandy lag concentrate which overlies the Pleistocene deposits was shown from coring results to occur beneath the Recent muds at depths of 20 to 25 m below the present lake level. The clay-mud surface is clearly disconformable at depths up to 30 m or more below lake level. Eireau-Cleveland Ridge Cores penetrating through the mud have recovered samples of sorted (beach ?) sand overlying the crest and slopes of the northern and southern sections of the ridge at depths of 22 to 26 m. Western Lake Erie Possible dessication cracks were observed, with the aid of SCUBA diving, on a brown, clay till surface which formed the lake bed in water at a depth of 11 m approximately 1 km southwest of Pelee Point (R. E. Deane, personal communication). The linear cracks are a few millimetres wide and are arranged in 4- and 5-sided polygons approximately 15 to 30 cm in diameter. They are believed to result from shrinkage of the till as it dried when the lake bed was subaerially exposed during a low level stage. The plant detritus found buried beneath inorganic mud is indicative of a shallow water environment with nearby marshy foreshores. The detritus, at depths of 11 to 14 m, is believed to have accumulated in shallow isolated basins of western Lake Erie when water in the remaining part of the lake had fallen to equal or lower levels. Buried plant material was also encountered by Hartley (1961b) in western Lake Erie. His cross sections, constructed from jetting and borehole data, show the surfaces of plant detritus-bearing beds occurring at various depths between 8.1 m and 14.2 m. Topographic maps of the Michigan and Ohio sections of western Lake Erie, showing flooded valley mouths and marshes bordering much of the shore, indicate this area has undergone submergence. Moseley's (1904) investigation of Sandusky Bay, in which he traced marsh vegetation remains and stream valleys beneath the Bay's bottom sediments to depths of 32 ft or more below the present lake leve, was perhaps the first demonstration of the prior existence of lower Lake Erie levels. Buried Channels The channels across Pelee-Lorain and Long Point-Erie ridges appear to be erosional features that are buried beneath the Recent mud. Their relation- EARLY LAKE ERIE SEDIMENTS 181 ship to adjacent basins as shown in Fig. 2 strongly suggests that they served as interbasinal discharge routes at a time when water levels were lowered to and controlled by the elevations of the channel floors (approximately 30 m below the present water level). A piston core, located in the eastern basin north of Erie opposite the eastern terminus of the channel across the Long Point- Erie ridge, recovered sorted fine to medium sand with detrital wood chips at a depth of approximately 35 m. The sand, now buried beneath 5.5 m of clayey silt mud, may be either a fluvial deposit laid down by water which discharged eastward through the channel or a beach deposit related to a low level stage in the eastern basin. All of the foregoing evidence indicates that in the central basin erosion occurred at greater depths in the past than at present. The evidence further suggests that this erosion was due to the wave action and drainage of a low- level lake (or lakes), the surface of which was at least 20 m and possibly 30 m below the present mean lake level. Evidence from western Lake Erie indicates that at one time parts of this area were subaerially exposed while other lower parts contained shallow pools of water in which plant matter accumulated. Later, this area was flooded by rising lake water which deposited inorganic Recent mud throughout the basin.

AGE OF EARLY LAKE ERIE The erosion features occur on glacial or glacio-lacustrine materials, and where buried these features are covered only with Recent lacustrine sediment. The low-lake stage is therefore a postglacial feature which followed the high- level glacial lake stages in Erie basin and preceded modern Lake Erie. It is known as Early Lake Erie. The pre-Early Lake Erie series of glacial lakes, Whittlesey to Early Al- gonquin (see Hough 1963; and Fig. 7 in Wayne and Zumberg 1965), were prevented from draining northeastward by ice which occupied the Ontario basin and at times the eastern Erie basin. Early Lake Erie must have come into existence simultaneously with Lake Iroquois in the Lake Ontario basin when the ice had retreated sufficiently northeastward to allow water levels to fall in the Ontario basin to the elevation of the Rome, N.Y., outlet. From this time to the present, the Erie basin water was free to drain over the Niagara escarpment via the Niagara River. The inception of Early Lake Erie then is bracketed in time by the age of the last glacial lakes in Erie basin and the beginning of Lake Iro- quois. An average of three radiocarbon dates of Lake Whittlesey sediments (12,920 ± 400 years/W-430/, Alexander and Rubin 1958; 12,800 ± 250 years /Y-240/, Hough 1958; (12,660 ± 440 years /S-31/, Goldthwait et al. 1965) and an average of two dates on early Lake Iroquois sediments (12,660 ± 400 years /W- 861/, and 12,080 ± 300 years /W-883/, Alexander and Rubin 1960; E. H. Muller 1966, personal communication) place the inception of Early Lake Erie between 12,370 and 12,790 years B.P. This time range must also include the pre- Early Lake Erie and post-Whittlesey glacial lakes. Rooted plant remains within the Erie watershed at an elevation of 582 ft a.s.l. near Tupperville, Ont., were dated at 11,860 -4- 170 years (GSC-211) and 12,000 ± 200 years (S-172) and reported by Dreimanis (Goldthwait et al. 1965; Dreimanis 1964). Because plants could only become established at this elevation after the drainage of the last glacial lake, these dates provide a direct minimum age for Early Lake Erie. Thus the low water stage within the Erie basin was probably in existence 12,370 years ago, and possibly as early as 12,600 years ago. This inference is compatible with two radiocarbon dates obtained during this study on organic material buried within the Recent mud in uncertainty. height representsthedepthof wateruncertainty.Thebaseoftherectanglesrepresents age of therectanglesrepresents the FIG. 182 time oftheglaciallakestagesomepointwhichliesnearorwithin these data—ageandelevation—defineonesetofcoordinatesanupliftcurve isobase orhinge-linedenotestheboundarynorthofwhichdifferentialuplift their northernproximalareasandsufferednodeformationindistal taneously inundatedboththeundepressedareasdistantfromglacierand plant detritusrecovered14mbelowlakeleveland4thesediment- base (i.e.uplift)passingthroughit.Iftheageofshorelineisalsoknown, basin willbeequaltothatpoint'spresentelevationminusthevalueofiso- bedrock sillattheheadofNiagaraRiverBuffalo,N.Y.Nootherlower explanation ofthelow-levelstagesincentralandwesternLakeEriemustbe of shorelinedevelopmenttothepresent.Secondly,ancientelevationat occurred andsouthofwhichtherewasnodeformation(tilting)fromthetime drawn onstrandlineelevations,permitsomeinferencesconcerningthevertical depressed areasclosetotheglacier,builtshorelinesthatunderwentupliftin outlets whichmighthaveoperatedinpostglacialtimeareknown.Thereforethe of Clevelandandrecoveredfromcore2226. movement ofanypointwithinorneartheglaciallakebasin.First,zero for thepointinquestion. tends toreboundafterdeglaciation.Asaresultproglaciallakes,whichsimul- water interfaceincore1240fromwesternLakeErie;thesecond(10,200 southern areasfollowingdeglaciation.Isobases,orcontoursofequaluplift Buffalo. have demonstratedthattheearth'scrustisdepressedbyglacialloadingand 6 mbelowthesediment-waterinterfaceincentralbasin33kmnorthwest related tothehistoryofdifferentialverticalmovementpresentoutletat Lake Erie.Thefirst(11,300±160years/GSC-382/)isadateontheburied years /GSC-330/)istheageofdriftwoodburied28.5mbelowlakeleveland 3. Studies ofthedeformationabandonedancientglaciallakeshorelines The levelofLakeErieiscontrolledatpresentbytheelevation

Uplift curveforLakeErie's outletatBuffalo,N.Y.Fortheglaciallakesheight

ELEVATION OF LAKE ERIE OUTLET AT BUFFALO FEET ABOVE SEA LEVEL RESENT EVEL LEWIS, ANDERSON,andBERTI 4po LAKEERIE isobase TIME (YEARSBEFORE 0 LAKE LEVELS elevation uncertaintyandfor EarlyLakeErie, EARLY LAKEERIE LAKE epoo LAKE WHITTLESEY IROQUOIS LAKE WARREN PRESENT)

woo

I BEGINNING

LAKE ERIE OF EARLY 500 550 400 450 + 180 EARLY LAKE ERIE SEDIMENTS 183

The uplift curve for Lake Erie at Buffalo (Fig. 3) was constructed from the data of 3 glacial lakes (Whittlesey, Warren, and Iroquois) in addition to the evidence presented earlier of flooding in western Lake Erie. For Lakes Whit- tlesey and Warren, isobase values at Buffalo were inferred from maps prepared from shoreline elevation data in Leverett and Taylor (1915), MacLachlan (1939), and Karrow (1963). The range of three Lake Whittlesey dates (12,600 to 12,920 years) was assumed to bracket the age of that lake stage. Lake Warren has not been dated directly yet; its age was assumed to lie between the average Whittlesey age of 12,790 years and the average, 12,370 years, of early Lake Iroquois dates. A complete profile of Lake Iroquois isobases was constructed through Buffalo by fitting the incomplete Iroquois profile determined from Coleman's (1936) data to the complete Algonquin profile measured along the east shore of Lake Huron by Goldthwait (1910). The result indicated a zero isobase about 33 miles southwest (S 26° W) of Buffalo at an elevation of about 340 ft a.s.l. The difference of 10 ft between this estimate and Hough's (1958, p. 202) estimate accounts for the elevation uncertainity of Buffalo in Iroquois time shown in Fig. 3. The prominent Iroquois shoreline mapped by Coleman, the highest of all Iroquois shore features in western Lake Ontario basin, probably is related to a late phase of Lake Iroquois when water levels were at a maximum due to differential uplift of the outlet at Rome. The most probable age for this shoreline lies between 10,150 ± 450 years (I/GSC/-11), the oldest date for Early Lake Ontario, and 11,510 + 240 (Y/691), the youngest date for Lake Iroquois (Karrow, Clark, and Terasmae 1961). An age of 11,000 to 11,500 years B.P. was assumed for this Lake Iroquois strandline. The final point on the uplift curve represents the age and elevation of the buried plant detritus (core 1240) in western Lake Erie. The maximum depth of water (6 m) at this site was estimated from the vertical interval between the elevations of con- temporaneous deposits of sand and plant material. In a consideration of low lake levels due to differential uplift of the con- trolling outlet, it is important to determine over what area of the lake basin uplift occurred. A map of the known zero isobases of the glacial lake stages (Fig. 5 in Wayne and Zumberge 1965) shows the Warren hinge-line crossing Lake Erie in a southeasterly direction from a point on the north shore 30 km northeast of Erieau to a point on the south shore about 25 km southwest of Erie. The Grassmere hinge-line, if projected from the Lake Huron basin, would probably parallel the Warren hinge-line and cross Lake Erie through Long Point. Since Early Lake Erie did not come into existence until after Grassmere time, it seems likely that all of the differential uplift was confined to the eastern basin, and low water levels occurred at uniform depths below the present water surface throughout the stable central basin. A study of the uplift curve (Fig. 3) and the sediments in Lake Erie shows that Early Lake Erie began about 12,370 years ago at levels as much as 100 ft (30 m) or more below present lake level. The central and western regions were essentially drained, and plant detritus accumulated in shallow ponds. Lake levels rose rapidly as the outlet at Buffalo was uplifted and water flooded the drained parts of the lake basin. The present level of Lake Erie may have been attained some 9,000 to 10,000 years ago.

PALYNOLOGICAL STUDIES Studies of sedimentation and geochronology of the Lake Erie basin are supported by pollen analysis. This investigation has shown that pollen grains are incorporated and preserved in the sediments of deep lakes and are helpful in interpreting sedimentological changes and establishing stratigraphic correla- 184 LEWIS, ANDERSON, and BERTI tion between cores from different parts of the basin. In addition, palynological findings indicate late-glacial and postglacial climatic conditions which prevailed during that time in the Lake Erie region. When coupled with radiocarbon analysis, palynological studies can be used to estimate the age of deglaciation and the time when vegetation became established in the area.

Methods Three cores, numbers 1240, 1244 and 2226 (see Fig. 1 for location), were selected for palynological studies. Core 2226 was used as one complete core and core 1240 as another, except for the part containing the organic layer which was submitted for radiocarbon analysis. Consequently, the organic section of corresponding stratigraphic position from core 1244 was chosen to bridge the missing interval in core 1240. Samples of 1 cc were obtained at varying intervals throughout the cores, taken farther apart in the uniform silty clay sediment and closer together where rapid changes in sedimentation were apparent. The samples were treated with hot hydrofluoric acid for 15 mm and left to cool. They were placed in centrifuge tubes, washed and centrifuged following treatments with hydrochloric and glacial acetic acids. The acetolysis procedure followed and the samples were mounted in Hoyer's solution for microscopic study. Slides were examined with a Leitz Ortholux microscope at 100x and 420x magnifications. Oil immersion was used for specific identification and study of pollen morphological details. Traverses of the slides were made until at least 200 arboreal pollen were counted. For some samples, as many as three and four slides were completely traversed to accumulate the desired number of pollen grains. The postglacial silty clay contained pollen in abundance, but the absolute pollen frequency decreased rapidly downward in the late-glacial deposits. Diagrams based on pollen and spore counts are shown in Figs. 4 and 5. The amounts of different pollen and spores are shown as percentages of total arboreal pollen. In Fig. 4, sections AB and EF represent core 1240 and section CD represents core 1244.

Results In Fig. 4 section EF, representing the lowermost sediments studied, pollen and spores are scarce, probably owing to rapid sedimentation, the lack of local vegetation or possibly redeposition from older sediments. Section CD shows the first signs of vegetation becoming established locally. Most of the interval CD is characterized by high Picea (spruce) which gives way to Pinus (pine) at the top of this interval. Section AB is represented in the lowermost portion by a Pinus maximum. The Pinus percentage drops off quite rapidly and hardwood deciduous trees such as Quercus (oak), U/mus (elm), Carya (hickory), Acer (maple), Fraxinus (ash), Tilia (basswood) and Jug-lans (walnut) dominate the remainder of the section. At the 10.2-ft depth the non-tree pollen total reaches 75% due to high percentages of Gramineae, Rosaceae and other unidentified pollen which is similar to pollen in the genus Spiraea. In Fig. 5, high Picea percentages characterize the basal portion of the profile. Picea delines and Pinus increases to a maximum. A decrease in Pinus in the middle and upper sections of the profile is accompanied by an increase in Quercus, Betula (birch), Salix (willow), Fraxinus and U/mus. Wood from the 20-ft level in core 2226 was dated at 10,200 ± 180 years (GSC-330), and the organic layer at 12.9 ft from core 1240 yielded a radiocarbon age of 11,300 + 160 years (GSC-382). This latter date represents the establishment of vegetation and deposition of organic matter at low levels in the Lake Erie basin. d z 1 ! SealmentS1 Arboreal Pollen I Pollen Spores WM Me.. Th. A •I r: rik, k i...... 1 ■ Spo 1 i al • . 12 My i Spa. •

Faintly 1 : i 4r •

laminated I Th soty slay

1 I Th. I Ly. I 1 7. containing AMIVS

a few shells 1 II I I II ■ I /111I, c° °° 1 L — F I 11 NELL l b./ I I■1Ib. """ •"''/ . •

111 • V IIIIMMOP" ■ ■ ,. k1111/ MI/ Z.1.7„. • HNIFI ? I I/ I Py. hr.:"... .. I I / , • • t . tirr c z " ..„...... _.. _,,.. My. Sax

Me. Spa. Th. HIIIH with sandy r ima I.Z.Vt. i Interbed als r L..- D R +R I

Thinly laminated 1 gray silt w th SINHIAIICIaS i ...... Or clay blebs ------2 Stratified clay

F, and fine sand 55 1 1r 14 52' MY 757 5 7 10‘ Porten age of total arboreal pollen •-present s.4.-atnindant ...re-very Munn:lent C-14 Oat* 11,3002160(0SC-382) Peat from core 1240P A pollen dia gram of lake smiimentS 2 -mombers of pollen one spores counted Aber...nuCor-Coryoollyilaceoe Abbreviations:Pm-Poitmonlateme Ly-Lythroceoe LAKE ERIE Py-Poly onamme Me-Sfenyonthes RO-Publoseaeg klm-Slyrlaphyllum Sax-Sasifropamme My-AlyrIca A E Spo-Spar aniurn fh.b.14upllar B F CORE 1240P CORE 1244P Th,Millstromg Ny-Symphaea Pt-Vitas..

FIG. 4. Pollen diagram showing the postglacial sequence from the western basin of Lake Erie. Pcolen Spores MIS Seal Is I Arbor al mien Nonarpor•al 0 ■ • 7 a •n C40 ik z.... I w my 0. • : W 7 1 1 N. MR EW, I =Mr'Ilh. Ells- r MP p I/ NM W IIIMIllfr M ■ ■ ■ 111/ i■ MINNEMP a a • • • rd.-r MIM■ ■ r W r I • 4•• 5 I Will■ ) W

Famtiy — 1111 I I I a I 1 a rn i n a lf d cyp ir liw .. 1 .. a I I `simaq I _ Contain,

7.; a few shells Ilk r 1 1 • MEW vMO& • • • t 15 II I ir r • a ■ `Nosuaamv m al a •:. 1a - . am I / I II ra Cy p ir

, — . . cyp PUE 1 sr v v . a I' 20 > Spa r I .: r = I a I ! 1 ' • Tniniy MI i V I

. iarnmatecl V I I I , • LIIIHEI silly clay Eii V • 1■11/ I / I I I I I 25 wan ts I sand lenses IIEW II I ,,, 2 2 Clay with 28 s•he lenSes 25 45 IS 30 25 50 75 42 7 32 7 35 70 8222 15 35 2 2 2 25 3 3 6 4 82 15 3 20 2 Percentage of total arboreal mien • C - Id date 10.200 t180 (GSC -330/ P7107 Megrim of lase sediments LAKE ERIE APPrewationsCar-Caryonnyllaceae 2-Numbers- preSent of pollen and spores counted E-EmcaceaeCyP-Cyperaceae CORE 2226 eisci•••.abonclant very apundant SNP-Mymophsolum Soa-Sparganiurn FIG. 5. Pollen diagram of the postglacial sequence from the central basin of Lake Erie. EARLY LAKE ERIE SEDIMENTS 187

Discussion The postglacial history of vegetation including a short late-glacial period at the base of the profiles is illustrated in Figs. 4 and 5. Insofar as the palynological record might be used for correlation of sediment sequences elsewhere in the Lake Erie basin, this record has been divided into recognizable pollen zones based on pollen frequencies and representing forest sequences such as were proposed by Sears (1942) more than twenty years ago. Because of the primarily geological application of palynological evidence in this study, this somewhat old-fashioned way of emphasizing pollen of a limited number of forest tree species and certain kinds of non-tree pollen has been utilized. A further reason for this treatment of the palynological record lies in the expedi- ency of analytical work. The interpretation of the record rests heavily on the reliable correlation of it with other, and more detailed, palynological records from the same region. The two pollen diagrams have been divided into pollen zones according to the following characteristics. The climatic interpretations are based on the inferred correlation with other available pollen records from the Lake Erie region. In Figs. 4 and 5, zone I corresponds to the Picea (P. mariana and P. glauca) maximum and a brief Abies (fir) maximum. These two genera were able to invade an area with a cold and moist climate which prevailed south of the retreating ice and to become pioneers of the invading vegetation. Non-tree species belonging to Cyperaceae and Equisetum were tolerant to this type of climate and they too became abundant (Fig. 4). Towards the top of zone I in Fig. 4, coinciding with a decrease in Picea (spruce), Abies, Cyperaceae and Equisetum there was an invasion of Larix (tamarack), Tsuga (hemlock) and hardwood deciduous genera such as Betula, Carpinus (blue beech), Ostrya (ironwood), Quercus and Ulmus along with minor increases in Artemisia, Ambrosia, Compositae, Gramineae, Typha and Rosaceae. Zone II is marked by a decrease in Picea and Abies to a minimum and an increase in Pinus ( P. banksiana) to a maximum. Probably the climate changed from rather cool and wet to cool and dry. Deciduous hardwoods such as Carpinus, Ostrya, Quercus, Betula, Ulmus, Carya, Acer, Fraxinus, Tile and Juglans became established and with Pinus (pine) as dominant formed a Pine-Oak-Elm-Hickory forest as evident in Fig. 4. Zone III, as observed by Sears (1942) in profiles from northcentral Ohio and characterized by Tsuga and Fagus (beech) maxima, is not clearly represented in the Lake Erie profiles. The reason for this lack of representation is not apparent at present although it is noted that zone III is not clearly de- fined in Potter's (1947) pollen diagram of Birmingham Bog, Lorain Co., Ohio. Zone IV is characterized by high percentages of pollen of deciduous tree genera such as Betula, Carpinus, Ostrya, Quercus, Ulmus, Carya, Acer, Fraxi- nus, Tilia and Juglans. This type of forest with oak as dominant suggests a warmer and drier climate than that which prevailed during the Pinus maximum of zone U. In Fig. 4, zone V displays a slight increase in Pinus, Tsuga, Betula, Fagus, Fraxinus, and total non-tree pollen of which Cyperaceae appears pre- dominant, and a decrease in Quercus, Tile, and Juglans. This would suggest that the climate was more moist and not so warm as that of zone IV. Zone V appears to be absent in Fig. 5 and is apparently truncated in Fig. 4. These effects may be due to (a) a discontinuance of sedimentation in the western and central basins and (b) loss of the uppermost sediment during the coring proc- ess. Further research in the form of studies on cores from the deep eastern 188 LEWIS, ANDERSON, and BERTI basin where sedimentation is presumably undisturbed and on cores from central and western Lake Erie, taken with care to avoid loss or disturbance of the soft mud at the sediment-water interface, is required to solve this prob- lem. The existence of an Early Lake Erie low-water stage, as apparent from the sequence of sediments, is supported by palynological studies. A marshy type of vegetation seems to have existed in the western basin of Lake Erie at the time of the Picea maximum (Fig. 4). The presence of pollen of spruce, fir, tamarack, hemlock, birch, alder, willow, sedges, grasses, cat-tails, and horse- tails suggests that the vegetation was marsh-like with species of oak, blue- beech, ironwood, elm, hickory, maple and walnut scattered about. This shallow pond environment slowed or prevented decomposition, and organic matter accumulated. The buildup in organic matter aided invasion of numerous shallow water plants. These plants produced an abundant supply of pollen which was blown about and became incorporated into the sediments. In Fig. 4 at the Quercus and U/mus maxima, (10.2 ft), the low-water stage is marked by high percentages in Gramineae, Rosaceae and other unidentified pollen recognized as being similar to pollen in the genus Spiraea. High percentages of Spiraea pollen were observed by R. J. Mott, Geological Survey of Canada, in the upper organic silty layer from the St. Clair River Delta. These large numbers were attributed to the widespread growth of this shrub on the delta during deposition of this layer. The high nonarboreal pollen percentages at the 10.2-ft level in Fig. 4, in addition to the presence of pollen of common lake plants in the genera, Menyanthes,Sparganium, Nuphar and Nymphaea, signify that the high peak in total non-tree pollen is of local influence. The anomalous abundance of nonarboreal pollen (NAP) at the 10.2-ft level (Fig. 4) might be due also to over- representation of species producing large quantities of wind-dispersed pollen and growing at great distances from the core site. The pollen diagram from the central basin (Fig. 5) does not contain a re- stricted zone with high non-tree pollen. The geological evidence, however, indicates that the site of core 2226 in the central basin may have been drained completely and the resulting erosional hiatus could account for the absence of a high NAP zone. As an alternative, one might envisage a rather large, residual lake in the central basin which would have prevented the existence of local vegetation near the coring site. It is anticipated that further palynological studies will provide satisfactory explanations for the above problems. The Lake Erie profiles and radiocarbon dates correlate well with pollen profiles and supporting radiocarbon dates from bogs in areas adjacent to Lake Erie. Sears (1942) found that profiles from bogs bordering on and south of the Great Lakes region show an abundance of spruce and fir pollen in the basal portion of the profiles. Pine pollen increased substantially above the Spruce- Fir zone and was followed by deciduous pollen belonging to the genera Betula, Quercus, Fagus, Ulmus, Carya, Fraxinus and Tilia. The forest vegetation changed from spruce and fir at the bottom of the profiles to pine with a minor concentration of hardwood species to a predominantly hardwood forest vegetation towards the top of the profiles. The pollen profiles and radiocarbon dates from Sunbeam Prairie Bog, Ohio (Kapp and Gooding 1964) also correlate with and support the pollen records and radiocarbon dates from Lake Erie. These show a Picea maximum during late-glacial time which decreased quickly and was followed by a Pinus maximum. Later, Pinus declined and hardwoods such as Quercus, Carya, Acer, Fagus, Tilia and Juglans increased rapidly. Spruce wood at the Picea maximum was dated at 11,700 + 250 years (L-550C) and peat at the Picea decline and Pinus emergence yielded a date of 10,600 + 150 years (L-550B). EARLY LAKE ERIE SEDIMENTS 189

Potter (1947) made a palynological survey of a number of peat bogs in northcentral Ohio. In establishing the forest sequence following retreat of the ice, he found that the order of first appearance was as follows: Picea, Abies and Pinus, Betulaceae, Quercus, Tsuga, Carya and Fagus. The sequence, shown by the Lake Erie profiles compares favourably with that from peat bogs number 4, 9, 10, 13, 15 and 19 studied by Potter, in which a late-glacial Picea maximum with a minor Abies maximum declined rapidly, and then Pinus became dominant and reached a maximum. Pinus then decreased and deciduous hardwoods such as Quercus, Carya, Fagus and others rose appreciably. Similarly, the Lake Erie diagrams compare quite well with a diagram from Torren's Bog, Licking County, Ohio, as interpreted by Gallein and Ogden (1965). The late-glacial Picea maximum is prominent in the basal portion; a short Pinus maximum follows the decline in Picea whereas Quercus, Ulmus and Carya dominate the remaining postglacial profile. A radiocarbon date of 12,820 + 444 years (OWU-90) from the high Picea period suggests that the date is compatible with the established retreat of the ice from the Lake Erie region. A pollen profile compiled by Terasmae (Karrow 1963) from Crieff Kettle Bog near Galt, Ont. north of Lake Erie, shows a similar spruce period at the base where a radiocarbon date of 11,950 + 350 years ((I(GSC)-29) was obtained. The postglacial climatic sequence interpreted from this profile is essentially similar to the climatic sequence interpreted from profiles south of Lake Erie, although some minor differences are evident. Gooding and Ogden (1965) made a pollen study of marl associated with a mastodon burial near Rochester, north-central Indiana. The 7-ft stratigraphic section showed a high Picea pollen content at the base along with minor amounts of Abies, Larix, Betula, Quercus and Salix. Pinus increased and became dominant midway through the section. Pinus decreased and Quercus, Carya, Ulmus and Salix became prominent towards the top of the profile. A radiocarbon-dated wood sample collected 90 inches from surface placed the age of the Picea maximum at 12,000 + 450 years (I-586). The pollen spectra from sediments that buried a mastodon in Gratiot County, northcentral Michigan, were studied by Oltz and Kapp (1963). At the 85-cm level, there was a noticeable decrease in Picea and an increase in Pinus and slight rises in hardwood deciduous pollen of Betula, Corylus, Fraxi- nus, Quercus and Salix. The mastodon recovered at approximately 90 cm from the surface dated at 10,700 + 400 years (M-1254). This date compares favourably with the Lake Erie core date of 10,200 + 180 years (GSC-330) at the level of the Picea decline and Pinus increase.

CONCLUSIONS The texture and stratigraphy of Lake Erie sediments has indicated past erosion in the central basin at levels much below the present erosion zones. Features, some of which are buried beneath the present mud surface, such as channels cut through till ridges, a gently sloping wave-cut terrace covered with a sandy lag concentrate, truncation of laminated sediments on the surface of glacio-lacustrine clays, deposits of sorted beach (?) sands, and buried plant detritus accumulations all suggest that low water levels at least 20 m and possibly 30 m below present lake level have occurred in the Erie basin in postglacial time. Early Lake Erie, the low-level stage, began at least 12,000 years and probably 12,370 or more years ago when the lake first drained via the Niagara River into the Ontario basin following deglaciation of that area. The western basin was essentially drained and plant detritus accumulated in 190 LEWIS, ANDERSON, and BERTI residual shallow ponds. Water in the central basins discharged eastward via channels cut through the Pelee-Lorain and Long Point-Erie ridges into the deep eastern basin. Rapid uplift of the outlet at Buffalo caused water levels to rise quickly and flood stream valleys and the previously exposed lake bed and to approach the modern lake level about 9,000 to 10,000 years ago. Wave activity associated with the transgressive levels of Lake Erie progressively eroded the basin at successively higher levels, planed off topographic irregu- larities, produced a gently sloping sand covered terrace and built beaches (?) at various levels. The fine-grained fraction of the eroded deposits was transported and deposited as a soft silty clay mud in offshore basins where it covered many of the Early Lake Erie features. Lacustrine sand and gravel deposits usually originate through the action of littoral processes. Hence, the foregoing concept of a low-level Early Lake Erie whose shorelines now may be submerged or buried beneath Recent mud provides a rationale for commercial sand and gravel exploration in Lake Erie. Sediment cores taken in western Lake Erie contain a palynological record extending back to late-glacial time. This record correlates favourably with others from outside of the Lake Erie basin. Because of the legible palynological record in sediments overlying Pleistocene deposits, it can be con- cluded that sedimentation was probably continuous and no significant disturbance has occurred owing to erosion and redeposition since low-level Early Lake Erie at the sites where the cores were taken. The Early Lake Erie low- water stage is evident both in the sediment stratigraphy and the pollen record. Furthermore, it is apparent that palynological studies can be used for a correlation of sediment sequences from different parts of the lake basin, and with those from the surrounding region. It is important to note that the established pollen record with adequate radiocarbon control for significant palynological marker horizons can be used for dating and correlation of sediments in the Lake Erie basin which do not contain sufficient organic matter for radiocarbon analysis. The following development of vegetation can be inferred from the pollen diagrams. The late-glacial episode dated at 11,300 ± 160 years B.P. was characterized by a predominance of spruce and fir, with smaller amounts of birch, alder, willow, and scattered occurrences of a few hardwood genera. The non-tree species were well represented, particularly Cyperaceae. This episode coincided with the low-water stage of Early Lake Erie, and was followed by a forest succession in which pine was prominent. Most of the subsequent time has been characterized by a Pine-Oak-Elm-Hickory-Maple forest. Other hardwood genera, the coniferous species and non-tree species were less important.

ACKNOWLEDGMENTS

The writers wish to thank the Great Lakes Institute, University of Toronto, for the provision of ship facilities, coring apparatus, and financial support during the field research. It was a pleasure to work with A. A. F. Hodge, Master, M Aesma, Chief Tech- nician, and their crews aboard the PORTE DAUPHINE during the coring and echo-sounding cruises on Lake Erie. We are indebted to the late Professor R. E. Deane, University of Toronto, for his inspiring supervision of the field programme and to Dr. J. Terasmae of the Geological Survey of Canada for advice on palynological matters. We are grateful to Professors A. Dreimanis, University of Western Ontario, E. H Muller, Syracuse Uni- versity, for comments concerning Great Lakes chronology and to Dr. Terasmae and Mrs. K. L. Edmond of the Geological Survey of Canada for critical review of the manuscript. We acknowledge with pleasure the support of several of our Geological Survey colleagues who aided in the preparation of this paper. EARLY LAKE ERIE SEDIMENTS 191

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