49 



CRESTON FORMATION. 



The Creston formation rests conformably upon the Ald- 

 ridge formation. A transition zone, 500 feet (152-4 m.) 

 in thickness, separates these two formations. The forma- 

 tion consists of a well bedded series of grey argillaceous 

 quartzites, purer quartzites and sandstones with thin inter- 

 calations of argillite. The beds are often cemented together 

 so that they form steep cliffs. In the western part of the 

 range these strata resemble coarse sandstones in appearance, 

 while, in the eastern, part, the quartzites are finer grained 

 and more argillaceous. The general weathering colour of 

 the lower part of the Creston formation is whitish grey. 



KITCHENER FORMATION. 



The Kitchener formation consists of thin bedded cal- 

 careous argillites, calcareous quartzites, argillaceous quart- 

 zites, and limestones, having a thickness of 4,500 feet 

 (1,368 m.). These strata weather reddish brown. Ripple 

 marks and mud cracks occur in them at several horizons. 

 Intruded into the formation are a few diorite sills, some 

 reaching a thickness of 100 feet (30-5 m.). 



SIYEH FORMATION. 



Lying conformably on the Kitchener formation and 

 passing into it by gradual transition is the Siyeh formation, 

 which consists of purple and grey siliceous argillites in 

 beds from i inch to 2 inches (2 • 54 to 5 • 08 cm.) thick. Some 

 dolomites and limestones are present in the upper part of 

 the formation. The argillites are characterized by the 

 presence of abundant mud cracks and ripple marks. 



PURCELL LAVA. 



The Siyeh epoch was brought to a close by the out 

 pouring of a basalt, called the Purcell lava. This lava 

 consists almost entirely of amygdaloidal basalt with small 

 amounts of rhyolite and breccia, and is the extrusive 

 phase of Purcell sills. 



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