SOIL SURVEY

-7-mainly in the Cataract Brook - Lake O'Hara area, is composed of massive thic kbedded, clean quartz sandstones or quartzites, with shale interbeds . Remainin gformations, which overlie the Gog Group, are dominated by massive limeston eand dolomite units, but also contain some slate and shale units (Cook 1975) .The Western Facies are made up of the Chancellor Formation, th eOttertail Formation and the McKay Group . The stratigraphic units which ar eassociated with the Western Facies are dominantly argillaceous (shales and slates) ,but also contain some carbonate units . As well, the lowermost unit of the ChancellorFormation has been altered to massive hornfels by recrystallization of th eargillaceous rocks under static conditions and elevated temperatures . With theexception of very localized outcrops, most of the hornfels outcrops are in th eUpper Porcupine Creek Area (Balkwill 1969) .Igneous rocks are exposed only in the Ice River area (with the exception o fsome very small alkali dikes and sills), where they comprise an area of about 1 2square miles (Allan 1914, 1954) . This is the largest known exposure of igneou srocks in the Rocky Mountains . Igneous rocks present are leucocratic type s(nepheline syenite), transition types (ijolites and urtilites), and melanocrati ctypes (jacupirangites and alkali pyroxenites) .Surficial Geolog yThe Pleistocene glaciers were one of the major factors in shaping th elandscape of Yoho National Park (Figure 2) . Rutter (1972), working in the BowValley just to the east of Yoho, found evidence of at least three and possibl yfour major Wisconsin age ice advances . Fox (1974) also found evidence offour ice advances in the Cataract Brook valley of Yoho National Park, th eearliest of which he tentatively correlated with Rutter's latest advance .Rutter (1972) and Fox (1974) both indicate that the later advances were