sign in sign up
<<
Home , Downtown Toronto, Etobicoke, Leaside, Metropolitan Toronto, North York, Rouge River (Ontario)

THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT

Your use of this Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use.

Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever.

Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”). Both your use of a linked Web site, and your right to use or reproduce information or materials from a linked Web site, are subject to the terms of use governing that particular Web site. Any comments or inquiries regarding a linked Web site must be directed to its Owner.

Copyright: Canadian and international intellectual property laws protect the Content. Unless otherwise indicated, copyright is held by the Queen’s Printer for Ontario.

It is recommended that reference to the Content be made in the following form: , . ; Ontario Geological Survey, , p.

Use and Reproduction of Content: The Content may be used and reproduced only in accordance with applicable intellectual property laws. Non-commercial use of unsubstantial excerpts of the Content is permitted provided that appropriate credit is given and Crown copyright is acknowledged. Any substantial reproduction of the Content or any commercial use of all or part of the Content is prohibited without the prior written permission of MNDM. Substantial reproduction includes the reproduction of any illustration or figure, such as, but not limited to graphs, charts and maps. Commercial use includes commercial distribution of the Content, the reproduction of multiple copies of the Content for any purpose whether or not commercial, use of the Content in commercial publications, and the creation of value-added products using the Content.

Contact:

FOR FURTHER PLEASE CONTACT: BY TELEPHONE: BY E-MAIL: INFORMATION ON The Reproduction of MNDM Publication Local: (705) 670-5691 Content Services Toll Free: 1-888-415-9845, ext. [email protected] 5691 (inside , United States) The Purchase of MNDM Publication Local: (705) 670-5691 MNDM Publications Sales Toll Free: 1-888-415-9845, ext. [email protected] 5691 (inside Canada, United States) Crown Copyright Queen’s Printer Local: (416) 326-2678 [email protected] Toll Free: 1-800-668-9938 (inside Canada, United States)

LES CONDITIONS CI-DESSOUS RÉGISSENT L'UTILISATION DU PRÉSENT DOCUMENT.

Votre utilisation de ce document de la Commission géologique de l'Ontario (le « contenu ») est régie par les conditions décrites sur cette page (« conditions d'utilisation »). En téléchargeant ce contenu, vous (l'« utilisateur ») signifiez que vous avez accepté d'être lié par les présentes conditions d'utilisation.

Contenu : Ce contenu est offert en l'état comme service public par le ministère du Développement du Nord et des Mines (MDNM) de la province de l'Ontario. Les recommandations et les opinions exprimées dans le contenu sont celles de l'auteur ou des auteurs et ne doivent pas être interprétées comme des énoncés officiels de politique gouvernementale. Vous êtes entièrement responsable de l'utilisation que vous en faites. Le contenu ne constitue pas une source fiable de conseils juridiques et ne peut en aucun cas faire autorité dans votre situation particulière. Les utilisateurs sont tenus de vérifier l'exactitude et l'applicabilité de tout contenu avant de l'utiliser. Le MDNM n'offre aucune garantie expresse ou implicite relativement à la mise à jour, à l'exactitude, à l'intégralité ou à la fiabilité du contenu. Le MDNM ne peut être tenu responsable de tout dommage, quelle qu'en soit la cause, résultant directement ou indirectement de l'utilisation du contenu. Le MDNM n'assume aucune responsabilité légale de quelque nature que ce soit en ce qui a trait au contenu.

Liens vers d'autres sites Web : Ce contenu peut comporter des liens vers des sites Web qui ne sont pas exploités par le MDNM. Certains de ces sites pourraient ne pas être offerts en français. Le MDNM se dégage de toute responsabilité quant à la sûreté, à l'exactitude ou à la disponibilité des sites Web ainsi reliés ou à l'information qu'ils contiennent. La responsabilité des sites Web ainsi reliés, de leur exploitation et de leur contenu incombe à la personne ou à l'entité pour lesquelles ils ont été créés ou sont entretenus (le « propriétaire »). Votre utilisation de ces sites Web ainsi que votre droit d'utiliser ou de reproduire leur contenu sont assujettis aux conditions d'utilisation propres à chacun de ces sites. Tout commentaire ou toute question concernant l'un de ces sites doivent être adressés au propriétaire du site.

Droits d'auteur : Le contenu est protégé par les lois canadiennes et internationales sur la propriété intellectuelle. Sauf indication contraire, les droits d'auteurs appartiennent à l'Imprimeur de la Reine pour l'Ontario. Nous recommandons de faire paraître ainsi toute référence au contenu : nom de famille de l'auteur, initiales, année de publication, titre du document, Commission géologique de l'Ontario, série et numéro de publication, nombre de pages.

Utilisation et reproduction du contenu : Le contenu ne peut être utilisé et reproduit qu'en conformité avec les lois sur la propriété intellectuelle applicables. L'utilisation de courts extraits du contenu à des fins non commerciales est autorisé, à condition de faire une mention de source appropriée reconnaissant les droits d'auteurs de la Couronne. Toute reproduction importante du contenu ou toute utilisation, en tout ou en partie, du contenu à des fins commerciales est interdite sans l'autorisation écrite préalable du MDNM. Une reproduction jugée importante comprend la reproduction de toute illustration ou figure comme les graphiques, les diagrammes, les cartes, etc. L'utilisation commerciale comprend la distribution du contenu à des fins commerciales, la reproduction de copies multiples du contenu à des fins commerciales ou non, l'utilisation du contenu dans des publications commerciales et la création de produits à valeur ajoutée à l'aide du contenu.

Renseignements :

POUR PLUS DE VEUILLEZ VOUS PAR TÉLÉPHONE : PAR COURRIEL : RENSEIGNEMENTS SUR ADRESSER À : la reproduction du Services de Local : (705) 670-5691 contenu publication du MDNM Numéro sans frais : 1 888 415-9845, [email protected] poste 5691 (au Canada et aux États-Unis) l'achat des Vente de publications Local : (705) 670-5691 publications du MDNM du MDNM Numéro sans frais : 1 888 415-9845, [email protected] poste 5691 (au Canada et aux États-Unis) les droits d'auteurs de Imprimeur de la Local : 416 326-2678 [email protected] la Couronne Reine Numéro sans frais : 1 800 668-9938 (au Canada et aux États-Unis)

r Ministry of Hon James A- c. Auld Minister MARGINAL NOTES REFERENCES Natural ^ ,,, D Dr. J. K. Reynolds INTRODUCTION Antevs, E. Deputy Minister 1928: The Last Glaciation with Special Reference to the Ice Sheet Ontario This Quaternary geological map presents the distribution and sequence Retreat in Northeastern ; American Geographical of recent and glacial deposits in the Metropolitan and surround Society, Research Series 17, 292 p. ing areas. The colours and patterns on the map depict the type of sedi -STOUFFVILLE ment on the ground surface. The profiles provide the local sequence of Bird, S. J. G. and Armstrong, J. L. 3 ONTARIO GEOLOGICAL SURVEY 1970: A Recessional Study; Proceedings, 13th sedimentary layers; the legend lists all of the deposits, generally from PRELIMINARY MAP P. 2204 oldest (at the bottom) to youngest (at the top). The legend is organized Conference, Research, p. 187-197. by origin of deposit (rivers, lakes, and ice); some units are therefore not Caley, J. F. GEOLOGICAL SERIES listed chronologically and footnotes provide time terms for those excep 1940: Paleozoic Geology of the Toronto-Hamilton Area, Ontario; Geo tions. logical Survey of Canada, Memoir 224, 284 p. Chapman, L. J. and Putnam, D. F. BEDROCK GEOLOGY 1966: The Physiography of ; QUATERNARY GEOLOGY Press, 386 p. The bedrock consists of shale, interbedded dolomitic siltstone, and minor Churcher, C. S. and Karrow, P. F. limestone, which were deposited in shallow seas about 450 million years 1963: Mammals of Lake Age; Canadian Journal of Zoology, ago. These beds, named the Formation, are approximately TOWN [ OF RICHMOND Volume 41, Number 2, p. 153-158. TORONTO 250 m thick and dip to the southeast at about 5 m/km. Following long periods of additional sedimentation and erosion, the ancient Laurentian 1977: Late Pleistocene Muskox (Ovibos) from the Early Wisconsin at River and its tributaries cut several deep, poorly-defined bedrock valleys Scarborough Bluffs, Ontario, Canada; Canadian Journal of Earth trending northwest-southeast across the area (see cross-sections). They Sciences, Volume 14, p. 326-331. AND have an important influence on drift thickness and groundwater distribu Clark, L. J. tion in the Toronto area. 1891: The Formation of Toronto Island; Canadian Institute Transcript, Volume 1, p. 37, 38, 239-246. JpWN OF SURROUNDING AREA TOPOGRAPHY Coleman, A. P.* 1894: Interglacial Fossils from the Don Valley, Toronto; American orrville M The landscape of Toronto and the surrounding territory features two Geologist, Volume 13, p. 85-95. SOUTHERN ONTARIO gently sloping surfaces divided by a prominent shore-bluff formed by 1895: Glacial and Interglacial Deposits near Toronto; Journal of Geology, glacial Lake Iroquois- South of this shore-bluff, the old lake bottom is Volume 3, p. 622-645. almost level. North of the Iroquois bluff, the surface is a gently undula Scale: 1:100,000 ting till plain that gradually rises towards the north until it meets the 1913: Geology of the Toronto ; p. 51-81 in The Natural History of Miles 1 0 1 234 Miles . This till plain includes several oval hills oriented the Toronto Region, Ontario, Canada, Edited by J. H. Faull, Briggs, l i i E i i i southeast/northwest. These indicate that glacial ice moved out 419 p. of the basin towards the northwest. Lake-bottom sediments 1933: The Pleistocene of the Toronto Region; Ontario Department of Kilometres 1 0 2 4 6 Kilometres did not cover these drumlins below the Iroquois bluff in the southeast Mines Annual Report, 1932, Volume 41, Part 7, p. 1-55. portion of the area. 1937: Lake Iroquois; Ontario Department of Mines. Annual Report, 1936, Volume 45, Part 7, p. 1-36, NTS References: 30M/11, 12E, 13E, 14 Dissecting these two sloping plains are large river valleys which, in part, mirror the preglacial river valleys cut in the bedrock surface. These large 1941: The Last Million years; University of Toronto Press, 216 p. OMNR-OGS 1980 Ontario Geological Surve valleys (of the Number, Don, and Rouge rivers) were not totally formed Czurda, K. and Quigley, R. M. MINES LIBRARY by present-day river discharge. Major erosion occurred during the drain 1973: Cracking of a Concrete Tunnel in the Meaford-Dundas Formation, age of a series of late-glacial lakes. , Ontario; Research Report, SM-3-73. Faculty of En gineering Science, University of Western, Ontario, 14 p. LEGEND QUATERNARY GEOLOGY Dreimanis, A. MUL 12 1990 1961: Tills of Southern Ontario; p. 80-96, in Soils of Canada, Edited by CENOZOIC The early studies and formal stratigraphy of the glacial and recent depo QUATERNARY R. F. Leggett, 240 p. ffi'*™ , Ave J sits in the Toronto area are summarized by Karrow [1969). The basic RECENT Dreimanis, A. and Terasmae, J. RECEIVED sequence of deposits, representing three main glacial and three nonglacial RECENT DEPOSn **fc periods, was known over 100 years ago. The Toronto sequence is famous 1958: Stratigraphy of Wisconsin Glacial Deposits of Toronto Area. Ontar io; Proceedings of the Geological Association of Canada, Volume across North America because of the well-preserved record of fossil-rich 15©. : Man-made deposits: fill. deposits indicating both warm-climate and cool-climate conditions. The 10, p. 119-136. warm-climate interglacial beds (Don Formation: 5c, 6c) indicate temper Fleming, Sanford 14 Lake Ontario beach and nearshore deposits: sand. ate climates, up to 30 C (average) warmer than present. The cool-climate 1853: Its Formation and Preservation; Canadian intraglacial beds (Scarborough Formation: 5b, 6b) indicate conditions Journal, Volume 2, p. 105-107 (December 1853) and p. 223-230 possibly 5D C cooler than present. Detailed studies of these fossiliferous (April 1854}. ,, OflNORTH YORK beds and adjacent glacial deposits have revealed an intricate story of the Freeman, E. B. Ol A \ iV 13 Modern river deposits: sand, silt, minor gravel and events and climates over the past 200 000 years in the Toronto area. The 1976: Toronto©s Geological Past An Introduction; Ontario Division of following description traces this history sequentially. Mines, Miscellaneous Publication. 1978: Geology of the Greater Toronto Region; p. 84-92 in Toronto ©78 QUATERNARY HISTORY Field Trips Guidebook, Geological Association of Canada, Geologi CARBOROUGH ICE-AGE DEPOSITS cal Society of America Annual Meeting, Edited by A. L. Currie and York Till: The oldest exposed glacial deposits in the Toronto area are W. O. Mackasey, 361 p. known as the York Till (unit 2d; see reference section, sections 1 and 2). Fricsbergs, Karl S. It is a dense clayey to sand till that has incorporated much of the under 1970: Erosion Control in the Toronto Area; Proceedings of the 13th ":-:*V^i-vV©© Older river deposits3 : sand, grave! in terrace remnants. lying Georgian Bay Formation, upon which it usually rests. This till is Conference, Great Lakes Research, p. 751-755, widespread, commonly being found in excavations in Toronto. GLACIAL LAKE DEPOSITS Gorrell, H. A. York Till underlies the interglacial Don beds and represents a glaciation 1952: The Dundas Formation as Exposed in the Excavations for the (Illinoisan Stage) predating the other tills (Wisconsinan Stage) in the 11 Lake Iroquois*3, beach or bar deposits: gravel, sand. Toronto Transportation Commission Subways; Proceedings of the Toronto region, about 200 000 years ago, Geological Association of Canada, Volume 5, p. 83-93. 10 Lake Iroquois, shallow-water deposits: sand, silty Don Formation: Following the deposition of York Till, climates wprmed Hewitt, D. F. dramatically, to about 3n C warmer than present day climate. The warm- 1969a: Industrial Mineral Resources of the Markham-Newmarket area; climate fossils are contained in deltaic deposits of clay, sand, and gravel Ontario Department of Mines, Industrial Mineral Report 24, 41 p. (units 5c, 6c|, representing the oldest in a series of lakes (Table 1) to 1969b:lndustrial Mineral Resources of the Brampton Area; Ontario De Lake Iroquois, deeper-water deposits: silt, clay. affect the Toronto area, This lake, called Lake Coleman, stood 20 m partment of Mines, Industrial Mineral Report 23, 22 p. i Qj 5/' i {65 feet) or more above Lake Ontario (75 m, 246 feet). Its deltaic de Hewitt, D. F. and Yundt, S. E. * Vs T IT i "*P r Lake Ontario 8 Peel ponds; shallow-water deposits: sand. posits cover about 65 km2 , with up to 10 m of sediment. The Don beds 1 971: Mineral Resources of the Toronto-centred Region; Ontario Depart (75 metres a.s.l.) are also commonly encountered in downtown excavations. BOROUGH OF ETOBfCCKF ment of Mines, Industrial Mineral Report 38, 34 p. Peel ponds; deeper-water deposits: silt, clay. TABLE 1 SUMMARY OF LAKES IN THE TORONTO AREA. Hind, H. Y. 1853: Notes on the Geology of Toronto; Canadian Journal, Volume 1, ROUGH OF YORK Lake Elevation 1 Age Deposits p. 147-151. Older lakesc ; shallow-water deposits; sand (Formations: 6a, Thornciiffe; 6b, Scarborough;6c, Don), m (feet) years B. P. 2 Hinde, G. J. a.s.l. 1877: Glacial and Interglacial Strata of Scarboro©s Heights and other Older lakes; deeper-water deposits: silt. clay. Lake Ontario 75 1246} present , beaches Localities near Toronto, Ontario; Canadian Journal, New Series, PURPOSE OF THE MAP (Formations: 5a, Thornciiffe; 5b, Scarborough; 5c, Don). Admiralty -o > 1 0 000 no deposits Volume 15, p. 388-413. Lake Iroquois 130 (425) 12500- 12000 spits, sand, silt Karrow, P. F. 1 GLACIAL ICE DEPOSITS Peel ponds 183+I600+) 13000- 12500 sand, silt 1967: Pleistocene Geology of the Scarborough Area; Ontario Depart Quaternary geology involves the events and deposits of glacial and Thornciiffe lakes 130+ (42B+) 50 000 - 22 000 Thornciiffe Formation ment of Mines, Geological Report 46, 108 p. recent times: elements that have shaped the landscape and soil strata Ice-contact deposits: sand, gravel, silt in eskers and low lake stage < 69 K 255) 75000 Pottery Road Formation 1969: Stratigraphic Studies in the Toronto Pleistocene; Proceedings of of the Toronto region. The purpose of this map, then, is to summarize morainic ridges. Lake Scarborough 1 22 (400) ~ 90 000 Scarborough Formation the Geological Association of Canada, Volume 20, p. 4-16. existing information concerning the Quaternary (and bedrock) geology Lake Coleman 95 (310) ^- 125000 Don Formation Karrow, P. F. of this region. This map serves as an introduction to further geological Young tills b : clayey silt till [Wildfield, 3a; Halton, 3b) 1970: Pleistocene Geology of the Thornhill area. Toronto; Ontario De and sandy silt till (Wentworth, 3c; , 3d). 1. All lake levels (where appropriate) are measured approximately from their partment of Mines, Industrial Mineral Report 32, 51 p. and geotechnical studies in the Toronto area. Therefore, the expected position at the Don Valley Brickyards. users include the general public, students, and earth-science profes 1974: Till Stratigraphy in Parts of ; Geological 2. B.P. Before present. ^^^^^^^^^^^^^^^^^^^^^ 2 Older tills0: silty clay to silt tilt (Meadowcliffe, 2a; Society of America Bulletin, Volume 85, p. 761-768. sionals. This is part of a series of publications that will outline the Seminary, 2b; Sunnybrook, 2ct to clayey sand till urban geology, including engineering aspects, of the Toronto area. Examples of important fossil remains include Black Locust (a tree which Karrow, P. F., Clarke, A. H., and Herrington, H. B. (York,2d). 1972: Pleistocene molluscs from Lake Iroquois Deposits in Ontario; presently grows far to the south of Toronto}, insects, bison, and large This publication is composed of several elements. The geological map fresh-water clams, which are key indicators of these beds. The warm- Canadian Journal of Earth Sciences, Volume 9, p. 589-595. PALEOZOIC (scale 1:100 000) is supplemented by north-south and west-east cross- climate Don beds lie between the deposits of two major glacial episodes Karrow, P. F. and Morgan, A. V. ORDOVICIAN and have been correlated to the Sangamonian Interglacial, judged to be 1975: Quaternary Stratigraphy of the Toronto area; Waterloo ©75, Field sections (scale 1:25 000) drawn along the subway routes. The de BEDROCK older than 125 000 years. ; Trips Guidebook, Geological Association of Canada, 330 p. tailed geology of well-studied locations is presented as reference sec Karrow, P, F., Harrison, W., and Saunderson, H. C.* tions. More specific information is available from the individual maps Shale, interbedded siltstone, and minor limestone, (Georgian Bay Formation). Scarborough Formation: Another old lake. Lake Scarborough deposited 1977: Reworked Middle Wisconsinan (?) Plant Fossils from the Brampton Lake Ontario (see index map) and the bibliography. deltaic sediments (units 5b, 6b) up to 50 m thick at an elevation reaching Esker, Southern Ontario; Canadian Journal of Earth Sciences, (75 meires a.s. l J 47 m (154 feet) above Lake Ontario. This high lake level was created by Volume 14, p. 426-430. Notes: advancing glacial ice blocking drainage down the St. Lawrence River, In Lajtai, E. Z. contrast to the underlying Don beds, the Scarborough beds contain a. Multiple age; 1 2a, deposited at levels lower than Lake Iro 1966: Pleistocene Sediments of the Bloor-Danforth Subway Section, quois; i2b. Pottery Road Formation; 12c, pre-Wisconsinan? fossils (plant fragments, pollen, and shells) that indicate cool-climate Toronto, Canada; Ph, D. thesis. University of Toronto, 109 p. (boreal) conditions, about 5 C cooler than present. These deposits cover 1967: Origin of some Varves in Toronto, Canada; Canadian Journal of b. Late Wisconsinan. about 195 km2 and they are prominently displayed along the Scarborough Earth Sciences, Volume 4, p. 633-639. c. Middle Wisconsinan and older. bluffs {see reference section 3). Here, the deltaic deposits consist of a 1969: Stratigraphy of the University Subway, Toronto, Canada; Pro lower clay member and an upper sand member, a situation that leads to ceedings of the Geological Association of Canada, Volume 20, excessive seepage of groundwater and piping at the sand/clay boundary. p. 17-23. SYMBOLS The Scarborough Formation, about 90 000 years old, represents the earliest Wisconsinan age deposits in the Toronto area. Lewis, C. F. M. and Sly, P. G. 1971: Seismic Profiling and Geology of the Area of Pottery Road Formation: Lake levels in the Toronto area fell to an un Geological boundary, [line indicates Lake Ontario; Proceedings of the 14th Conference, Great Lakes Feet Metres known level (less than 69 m, 225 feet) following Lake Scarborough. Research, p. 303-354. approximate. direction of ice move ment). Rivers flowing into this low stage cut valleys that were partially filled Liberty, B. A. a.s.l. with sand and gravel. These deposits (unit 12c) are well exposed at the Geological boundary, 1964: Upper Ordovician Stratigraphy of the Toronto Area; Guidebook, Feet Metres Don Valley brickyard. The Pottery Road Formation is early Wisconsinan assumed. Small bedrock outcrop. Geology of Ce©ntral Ontario; American Association of Petroleum a.s.l. in age, based on its correlation with deposits at St. Pierre, , dated Geologists, p. 43-53. about 75 000 years B.P. Parks, W. A. Lake Iroquois shoreline. Sunnybrook Till Location of cross- Sunnybrook Till: As glacier ice returned to the Toronto area it moved out 1925: The Stratigraphy and Correlation of the Dundas Formation; section. of the Lake Ontario basin incorporating pre-existing deposits, especially Ontario Department of Mines, Annual Report, 1923, Volume Surinybmok Dritt Lake Scarborough clays. This ice then deposited a clay-rich till known as 32, Part 7, p. 89-116. Sunnybrook Ti the Sunnybrook Till (unit 2c| about 70 000 years B.P. This close relation Pullen, M. J. CROSS-SECTIONS AND REFERENCE SECTIONS ship to the Scarborough Formation and the widespread extent of such a 1966: The Pleistocene Geology of Toronto as Seen from the Bloor- uniform till sheet allows it to be an important marker bed throughout Danforth Subway Cut; M. A. Se. Thesis, University of Toronto, the area. 55 p. In order to expand the general information illustrated on the Quaternary map, two types of profiles have been added to the Quigley, R. M., Matich, M. A. J., Horvath, R. G., and Hawson, H. H. Thornciiffe Formation: Fluctuating lake beds created by nearby oscilla map. First, generalized cross-sections located along the existing tions of the glacier resulted (mainly) in the deposition of lake deposits 1971: Swelling Clays in Two Slope Failures at Toronto; Canadian Geo technical Journal, Volume 8, p. 417-424. subway routes show the depth and variation of the sediments (units 5a, 6a): stratified sands, silt, and varved clay. In the Scarborough to bedrock. Section W E, the subway line, illustrates region, two tills, the Seminary (unit 2b) and the Meadowcliffe (unit 2a) Robinsky, E. l. and Morton, J. D. the thicker, more complex sediments located in Scarborough interrupt this complex lake sequence. Fossil remains from these deposits 1973: Foundation Investigation for CN Tower, Toronto; 26th Canadian 200 relative to the thin deposits in . Section N S, the indicate cool-climate conditions similar to the Scarborough Formation Geotechnical Conference, Canadian Geotechnical Society, Toronto, 5 km subway line, shows thick sediment patterns north lake beds. Radiocarbon dating, however, shows the Thornciiffe Forma p. 237-245. of the Lake Iroquois shoreline and thinner deposits on the lake tion to date from roughly 22 000 to 50 000 years B.P. (Middle Wisconsin Rogers, D. P., Ostry, R. C., and Karrow, P. F. 1. Don Valley 2. Woodbridge 3. Stratigraphy of the Scarborough Bluffs an). 1961: Bedrock Contours, , Ontario Department of plain to the south. Mines, Map P. 102, Scale 1:12 000. Brickyard Railway Cut Horizontal scale is 1:24,000. Vertical exaggeration is x 8. Young Tills: Once again the glaciers returned, depositing younger tills Second, three reference sections are included as examples of the Sibul, U., Wang, K. T., and Vallery, D. (late Wisconsinan time) in the Toronto area. Included in this group (unit detailed geological information that provides the basis for ex 1977: Ground-water Resources of the Duffins Creek - 3) are several tills, the extent of which is not known in detail. Generally, tending the Quaternary stratigraphy in the Toronto area. The Drainage Basins; Water Resources Report 8, Ministry of the En REFERENCE SECTIONS dense sandy tills (Leaside, 3d, and Wentworth, 3c) underlie the clayey formal Quaternary stratigraphic names have been added to these vironment, 109 p. silt to silty tills (Halton, 3b, and Wildfield, 3a) and together cover most of (1-3) sections for the interested reader. the present land surface. These tills were deposited between 22 000 and Stupavsky, M., Gravenor, C. P., and Symons, D. T. A. 1974: Paleomagnetism and Magnetic Fabric of the Leaside and Sunny The reference sections are modified from: 1. Terasmae (196U; 13 000 years ago. brook Tills near Toronto, Ontario; Geological Society of Ameri 2. Karrow and Morgan 1975; 3. Karrow 1967. The subway Eskers and Kames: During this latest glacial episode, silt, sand, and gravel can Bulletin, Volume 85, p. 1233-1236. profiles were supplied by J. Wong of the Toronto Transit Com were deposited in subglacial channels and crevasses to form the esker and "!979: Paleomagnetic Stratigraphy of the Meadowcliffe Till, Scarbor mission with additional data from Watt (1954, 1957, and 1968). kame deposits (unit 4) of the Brampton esker and the Oak Ridges Moraine ough bluffs, Ontario: A late Pleistocene Excursion? Geophysical near Maple. Both of these deposits are overlain by the Halton Till (3b) of Research Letters, Volume 6, Number 4, p. 269-272. this glacial substage. Taylor, G. SOURCES OF INFORMATION 1936: Topographic Control in the Toronto Region; Canadian Journal Peel ponds: As the last ice sheet melted away, it ponded meltwaters that of Economics and Political Science, Volume 2. Number 4, p. 1-19. INDEX MAP Geology compiled (1980) from published maps (see index map). drained towards the Ontario basin. This created extensive shallow lakes Terasmae, J. Additional data were made available by the following: over large areas of Peel and adjacent . The lake deposits (units The following references were the source of most of the 1960: A Palynological Study of Pleistocene Interglacial Beds at Toronto, Feet Metres Metres Feet H. Q. Golder Associates Ltd. 7 and B) 1 , termed the Peel ponds, consist of a thin covering of sand,. surface geology. The areas of these maps are shown on the Ontario; Geological Survey of Canada, Bulletin 56, p. 24-40. a.s.l. a.s.l. Metropolitan Toronto Works Department silt, and minor clay. index nap. They are at a larger scale and will generally pro Thomas, R. L., Kemp, A. L. W., and Lewis, C. F. M. Toronto Transit Commission vide the user with more detailed infoimation for particular -200 Oy — 200 As waters fell to lower levels, the major river valleys of the Toronto region 1972: Distribution, Composition, and Characteristics of the Surficial 200-1 Ministry of Transportation and Communications (Ontario) were eroded and lateral terraces (unit 12] 1 were graded to these levels, areas. All have been published by the Ontario Department Sediments of Lake Ontario; Journal of Sedimentary Petrology, Ontario Hydro including those of glacial Lake Iroquois. (or Division! of Mines. 600 Volume 42, Number 1, p. 66-84. 600 City of Toronto Public Works Department Lake Iroquois: Lake levels stabilized while the water in the Ontario basin Trow, W. and Bradstock, J. 1. Coleman (1933): The Pleistocene of the Toronto Region; Metropolitan Toronto and Region Conservation Authority drained via the Hudson River at Rome, . This stable stage form 1972: Instrumented Foundations for Two 43-story Buildings on Till, ODM Map 41g. Scale 1:63360. City of Toronto Planning Board ed the prominent shoreline features of glacial Lake Iroquois between Metropolitan Toronto; Canadian Geotechnical Journal, Volume 2. Hewitt (1969a): Industrial minerals of the Markharn- 500-. 150- •500 John Westgate, unpublished data 12 500 and 12 000 years B.P. Westward moving lake currents built sandy, 9, p. 290 303. Newmarket area; ODM Map 2124. fr© Drafting by D. C. Roumbanis and Lorraine Farrell. pebbly spits or islands (unit 11), which are similar to the present Toronto Wan, A. K. Scale 1:63360. Islands. A well-marked shoreline, including bluffs up to 15 m high, was 1954: Correlation of the Pleistocene Geology as Seen in the Subway with 3. Hewitt (1969b): Industrial mineral resources of the Design by D. R. Sharpe and Raimonds Bafgalvis. established across the centre of the City of Toronto, south of St. Clair That of the Toronto Region, Canada; Proceedings ot the Geological 400-. 400 Brampton area; ODM Map 2176. Avenue. In Toronto, the elevations for this shoreline range from 53 m Association of Canada, Volume 6, p. 69-81. Base-map supplied by the Public Works Department, City of Scale 1:63360. Toronto. (174 feet) in the east, to 61 m (200 feet) in the west, above Lake Ontario. 1957: Pleistocene "^eology and Groundwater Resources of the This is due to warping of the land-surface following glaciation. Additional 4. Karrow (1965): Pleistocene geology of the Scarbor 100 of ; Ontario Department of Mines, Annual Report 300-. -300 Metric Conversion Factor: 1 foot = 0.3048 m Lake Iroquois deposits include a general covering of sand (unit 10) below 1955, Volume 64, Part 7, 64 p. ough drea; ODM Maps 2076 and 2077. the shoreline, to a silty bottom cover (unit 9) in the eastern extent of the Scale 1:31 680. 1968: Pleistocene Geology and Groundwater Resources, Township of This map is published with the permission of E. G. Pye, Director, lake plain. Etobicoke; Ontario Department of Mines, Geological Report 59, 5. Karrow (1970): Pleistocene geology of the Thornhill Ontario Geological Survey. Recent deposits: Due to extensive valley erosion during late-glacial and 50 p. area; ODM Preliminary Map P. 244. 200 -200 Scale 1:25000. Issued 1980 recent times, modern river deposits (unit 13) are spread over very wide White, O. L. 50^ floodplains of the modern rivers. Sediment supply to Lake Ontario by 1975: Quaternary Geology of the Bolton Area, Southern Ontario; Ontar 6. Watt (1957): Pleistocene geology of the Township of these rivers and by bluff erosion at the Scarborough bluffs has formed io Division of Mines, Geological Report 117, 119 p. North York; ODM Map 1955-6. Scale o km 14 km Information from this publication may be quoted if credit is spits, creating the present Toronto Islands. Considerable fill (unit 15) White, O. L. and Karrow, P. F. 1:31 680. given. It is recommended that reference to this map be made in has been added to the islands and waterfront since about 1910, especially 1971: New Evidence for Spencer©s Laurentian River; Proceedings of the 7. Watt (1968): Pleistocene geology of Etobicoke, ODM the following form: for such new projects as Harbourfront, Ashbridge©s Bay, and Bluffer©s SECTION N-S 14th Conference, Great Lakes Research, p. 394-400. Map 2111. Scale 1:31 680. Sharpe, D. R. Park. (Yonge Street subway) ©Contains additional earlier references. 8. White (1973): Quaternary geology of Bolton; ODM 1980: Quaternary Geology of Toronto and Surrounding Area; 1 Due to the scale and availability of the mapping all of these deposits may Map 2275. Scale 1:63360. Horizontal scale is 1:25,000. Vertical exaggeration is x 10. O.ntario Geological Survey Preliminary Map P. 2204, not be shown. Geological Series. Scale 1:100 000. Compiled 1980. Note; This index includes only the most recently published map for an area.

Feet Metres Metres Feet a.s.l. a.s.l.

600 -600

500 .-500 O^ ovir Lake Iroquois bluff 400 llliiiH"1"""^ --400

--300

200- --200

O km

SECTION W-E {Bloor Street subway) Horizontal scale is 1:25,000. Vertical exaggeration is x 10.

Reprinted 1990