Paleozoic Geology

Map 2339 ORANG EVILLE Paleozoic Geology ONTARIO DIVISION OF MINES HONOURABLE LEO EERNIER, Minister of Natural Resources DR .l. K REYNOLDS, Deputy Minister ofNaluraI Resources G A Jewett, Executive Director. Division of Mines E, G Pye, Director, Geological Branch The Niagara Escarpment trends north-south through the extreme eastern part of the map-area though it is largely obscured by relatively thick deposits oi Pleistocene glacial driit. Silurian strata upon the dip Adjniris Map 2340 slope of the Escarpment form the bedrock of most of the area. In the 30°30’ east the glacial deposits overlying the plateau of Silurian strata have M°m’ generated an irregular hummocky topography with relief of 200 to 300 feet. Amount of relief decreases westwards and the physiography of the western half of the map-area is dominated by the drainage system oi the southward ilowing Grand River Older (Ordovician) rocks are exposed only in the northeastern and southeastern corners of the area \ where the Nottawasaga and Credit Ftivers have cut re-entrants into the Escarpment. 'n;WhiDri.gtoriQ STRATIGRAPHY ‘{ Oueenston Formation (Upper Ordovician-Richmondian) Beds oi this unit are exposed only in the deeply incised river valleys at the eastern i W=t='l°°~imci.en.r edge oi the map-area. The lower boundary of the unit is not exposed ‘Cambridge although outcrops in the Nottawasaga River at Glen Cross may be close to the gradational boundary with the underlying Georgian Bay Forma- tion The lithology of the Oueenston Formation is consistent throughout -Wimdslvck 'BrzritIord M 2343 Niagara F"a 5 the area Dark red, hematitic.blocky, non-iissile calcareous shale seams "' Map 234 up to B leet in thickness typify the formation; thin to medium beds of . grey, sublithographic, argillaceous limestone occur, periodically, interbedded with the shales. Grey-green reduction zones subparallel or transverse to bedding are common. In the southeast, between Cataract Belfountain, a minimum thickness of 150 feet of Oueenston shale and ‘ may be inferred along the valley of the northern arm oi the Credit Ftiver. eo° lnthe extreme northeastern cornerofthe map-area aminimum thickness 1 Inchto 50 miles oi 300 feet of Oueenston shale may be interred between exposures Scale at Glen Cross and the upper boundary of the formation exposed in the eastern head of the valley of the Nottawasaga River. Cataract Group (Lower Silurian-Alexandrian) Whirlpool Formation The Whirlpool Formation is exposed only in the southeastern and northeastern corners ofthemap-area. lnthe southeast it is exposed in the valley heads of the northern and southern tributaries oi the Credit River which has incised a narrow embayment into the Escarpment Similarly, in the northeastern part of the map-area, the LEGEND Nottawasaga River and its tributary have cut deeply incised valleys westward into the Escarpment The resistant sandstone beds produce a series of step like falls where crossed by the stream courses. A PALEOZOIC complete section through the unit is exposed at Cataract on the northern arm of the Credit River and again on the northern tributary of the SILURIAN Nottawasaga River where accessible, the sandstone has been exten- SALINA FORMATION)‘ sively quarried, none of the quarries being currently in use. The lower contact of the unit with the Oueenston Formation is sharp and erosional in nature I II 9 Argillaceous dolostone, evaporites. The Whirlpool Formation is typically a very tine-grained, light to medium grey coloured, tan weathering, calcareous sandstone; ouartz GUELPH FORMATION grains are subrounded to well rounded and well sorted. Bedding is thick to massive often with very thin grey-green argillaceous partings. Sedimentary structures are abundant and include a very fine planar 8 Brown or tan dolostone. sedimentary lamination. large and small scale cross lamination, sym- metrical, asymmetrical, and lunate ripple forms, and well developed parting lineation which produces a tabular to platy fracture oi massive AMABEL FORMATION beds.Towards the top of the formation sandstone beds become thinner 7a Eramosa Membern‘dark brown or with a proportionate increase in the amount oi interbedded shale There 7 black bituminous dolostone. is little change in lithology between the northern and southern areas 7 Unsubdivided: grey or blue-grey of outcrop. At Cataract the sandstone has a thickness oi l6 leet, dolostone. in the Nottawasaga tributary section a thickness oi almost 23 feet is exposed. FOSSIL HILL FORMATION Manitoulin Formation This unit everywhere overlies the Whirlpool For- medium mation with a sharp but conformable contact. it is well exposed in stream 6a Mott/ed grey or brown, to coarsely crystalline dolostone, sections and by quarrying activity for the Whirlpool Formation The formation is composed of thin- to medium-. irregularly bedded, medium to dark grey coloured, brown weathering dolostone and dolomitic lime- REYNALES FORMATION)‘ stone. These are finely crystalline with a high argillaceous content The beds are separated by thin, irregular, dark grey shale panings Pale 6b Brown.iinely crystalline to sublitho- weathering chert nodules are common, particularly in the lower beds graphic dolostone. oi the formation, increasing in abundance tothe north oithe area. Rellct textures indicate that the beds were originally bioclastic in nature with CATARACT GROUP an abundance of crinoid material. In the Cataract to Eiellounlain region CABOT HEAD FORMATION the formation has a minimum thickness of 18 feet. A full thickness of 43"55’ almost 27 ieet is exposed in the Nottawasaga tributary section. 6c Moll/ed green and red shale. Cabot Head Formation The recessive weathering nature of this formation has produced a gently sloping bench below the main escarpment The unit is poorly exposed in the map-area and outcrops are restricted MANITOULIN FORMATION to the steep sided valleys of the northern branch oi the Credit River and Nottawasaga tributary. The unit consists ofa relatively thick succes- Ed Grey or mottled brown, fine to me- sion oi light grey to light blue, slightly calcareous clay shale which is dium crystalline dolostone. lissile when dry but plastic when wet. Subsidiary hard beds of light grey. very finely crystalline, highly argillaceous limestone, siltstone and calcareous shale, occur throughout the succession. Strata possibly WHIRLPOOL FORMATION equivalent to the Grimsby Formation of the Niagara Peninsula occur towards the top of the iormation. These beds oi finely crystalline, dark 5e White or fan quartz sandstone. red hematitic, bioclastic limestone and shale, occur interbedded with normal Cabot Head shale over a thickness oi approximately l0 feet DISCONFORMITY—UNCONFORM|TY at Cataract and in the Nottawasagatributary section The lower contact ORDOVICIAN oi the Cabot Head is gradational, being placed at the level at which shale dominates over interbedded limestones and dolostones. A mini- QUEENSTON FORMATION mum thickness oi 35 feet of the formation is exposed in the section at Cataract In the Nottawasaga tributary section Cabot Head beds ‘ 5 Redshale. outcrop intermittently over a thickness of 50 feet. ’ Fossil Hill Formation (’?Fleynales Formation and Lions Head Member GEORGIAN BAY FORMATION)‘ eouivalents) (Middle Silurian-Niagaran) The upper part of the Reynales Formation of the Niagara Peninsula is represented in the southeast part 4 Grey-green and grey-b/us shale, ‘ ot the map-area by several ieet of strata overlying the Fossil HIIIForma- siltstone, limestone. tion Atthis Iatitudethe beds oithe Fleynales Formation have a character intermediate with the Lions Head Member oi the Amabel Formation of Bolton (1953, 1957).The Nottawasagatributary section inthe northeast- WHITBY FORMATION1" ern corner oi the map-area exposes a thickness of almost 2 feet of strata oi this transitional lithology overlying the Fossil Hill Formation 3 3 Grey-brown and black shale. Farther south, in the Brampton area (Map 2337) near Georgetown (Teliord, Bond and Liberty), the Fossil Hill and Fteynales-Lions Head transitional facies appear to be represented by strata of the lower and E LINDSAY FORMATION)‘ upper parts oi the Reynales Formation respectively. However, additional n. is to these g 2 Grey sub//(hographic limestone, ml- detailed stratigraphic work required confirm relationships. 2 As the map scale is limited the Fossil Hill Formation is mapped as a E nor dolostone. unit with the Cataract Group E In the map-area the Fossil Hill Formation is characteristically a brown 2 VERULAM FORMATION)‘ weathering, thin- to medium- irregularly bedded, fine to medium crystalline, bull to tan coloured dolostone. The beds are separated by 1 1 Grey limestone, minor shale. extremely thin, irregular shale partings The association of pentamerid brachiopods with halysitid, iavositid and syringoporid corals is typical oi the formation. The upper Fieynales-Lions Head transitional facies is composed of regularly bedded, white to tan weathering light grey not occur in map area. colouredextremelytinelycrystallinetosublithographicdolostone Shale fDoes content of the beds is reduced in the north of the area and the formation is lighter in colour The full thickness oi the Fossil Hill Formation (6.5 feet)and Fleynales- Lions Head strata 0.9 feet) is exposed at Cannings Falls on the Not- tawasaga River The contact oi the Fossil Hill Formation with the underlying Cabot Head Formation is also exposed at this locality and is sharp and conformable. Minimum thicknesses of 3.5 feet of Fossil Hill and 2.5 feet of upper Reynales are exposed

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