NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 205 



ing over of the disintegrated surface material in the path of the ad- 

 vancing sea and that brought into it by tributary streams. There is 

 almost no coarse material present in the Middle and Upper Cambrian, 

 Ozarkian and Ordovician, the prevailing deposits being calcareous 

 except in the Goodsir Trough of the geosyncline, where an immense 

 amount of argillaceous, finely arenaceous, and siliceous matter greatly 

 increased the thickness of the deposits of Upper Cambrian in the 

 Beaverfoot Trough in Ordovician time. In the central area of the 

 geosyncline, where limestones predominate, the same general charac- 

 ter of sediments continues from about the Fiftieth Parallel 200 miles 

 (321.8 km.) or more to the north. This includes the Bow Trough 

 and its extensions north and south. The conditions mentioned indicate 

 that the lands on the east were of low relief while those of the 

 western or Selkirk side of the geosyncline were moderately elevated. 

 From the west, where the drainage was favorable great quantities 

 of fine siliceous and argillaceous muds and slimes were carried to the 

 Goodsir seaway. These conditions changed at the close of Upper 

 Cambrian Chancellor time, and 2,000 feet (609.6 m.) of calcareous 

 deposits gathered, which now form the Ottertail limestones. Another 

 shifting of the western lands resulted in the resumption of the influx 

 of siliceous muds which, with calcareous matter, formed the 6,400 

 feet (1,950.7 m.) of shales and siliceous limestones of the Goodsir 

 formation. This shift of the source of sediments in Upper Cambrian 

 time is most marked in the Goodsir Trough, but it also occurs on the 

 eastern side of the geosyncline in Alberta, as is shown by the abrupt 

 change from the thick-bedded magnesian limestones of the Upper 

 Cambrian Lyell formation to the calcareous shale and interbedded 

 interformational conglomerate limestone of the superjacent Sabine 

 formation. 



The prevailing rock of the Ordovician (Canadian) ^ Sarbach for- 

 mation is calcareous on the eastern (Sawback Trough) and in the cen- 

 tral portion of the Cordilleran area in the Glacier Lake Trough, but 



^ The Sarbach formation is referred to both the Ordovician and Canadian 

 systems at various places in the text. This lack of uniformity of treatment 

 results from two things : first, the fact that the different parts of the text were 

 written at different times, and second, the desire to avoid writing two words 

 each time the term is used. It must be noted that the true Ordovician is much 

 more sparingly represented throughout the Canadian Rockies than the lower 

 beds now referred to the newer Canadian system. Dr. Walcott was willing to 

 follow Dr. Ulrich in regarding the Canadian beds as probably constituting a 

 separate system. — C. E. R. 



