PALEOZOIC STRATIGRAPHY OF ROCKY MOUNTAINS 249 



Cambrian formations at Blacksmith Fork, but has not been noted 

 in the Garden City formation. Amounts of shale comparable to 

 that in the Maxfield (about 180 feet, all told) are present only in 

 the Langston, Ute, and Bloomington formations at Blacksmith 

 Fork. 



Furthermore, flat-pebble conglomerate is abundant throughout 

 the lower 600 feet (about half) of the Garden City formatipn at 

 Blacksmith Fork, but has not been noted in the upper half of the 

 formation there at all. The relation noted in the Maxfield forma- 

 tion, of 480 feet of interbedded shales and limestones with flat- 

 pebble limestone conglomerate in the upper 10 feet only, could 

 thus not be matched in the Garden City formation. A sequence 

 almost precisely similar to that of the Maxfield formation does 

 occur, however, in the Bloomington formation. 



The Maxfield formation of the central Wasatch, therefore, is 

 probably of Cambrian age, and bears a striking likeness to the 

 Middle Cambrian Bloomington formation of the Bear River 

 plateau, 75 miles farther north. 



The close relation of the Canadian series to the Upper Cambrian 

 series. — If the upper limit of the Cambrian system in northern 

 Utah has been defined correctly, the changes which took place 

 between Canadian (or Chazyan) and Trenton time in the Rocky 

 Mountain-Great Basin paleogeographic province were more notable 

 than those which occurred between Upper Cambrian and Canadian 

 time in that region. The latest sediments assigned to the Upper 

 Cambrian are of the same type as the Canadian deposits, whereas 

 the sediments of Trenton age are very different from either of the 

 former. The erosion preceding the beginning of Trenton sedi- 

 mentation is known to have been extensive, whereas evidence of 

 erosion between Upper Cambrian and Canadian time is reported 

 from only one locality. 



The physical evidence thus goes to show that the affinities of 

 the Western Canadian are rather with the Cambrian than with the 

 higher Ordovician. 



Is the Osarkian system represented here ? — If the Ozarkian period 

 of Ulrich is represented in the western province, it must be by some 

 part of the Upper Cambrian-Lower Ordovician sequence above 



