NO. 24 



PTAR M K '.A MA STRATA RESSER 



The Brigham quartzite is seldom fully exposed. For this reason 

 it is omitted in the following comparisons. From the figures in the 

 foregoing table it is apparent that the thinnest Middle Cambrian 

 section is recorded on Mill Creek, west of Liberty. The next in order 

 is that of Two Mile Canyon and the thickest section is found near 

 Garden City. Thus it seems that the total thickness increases from 



northwest to southeast. Moreover, if the aberrent thickness for the 

 Bloomington formation in Two Mile Canyon is overlooked, remark- 

 ably little variation appears among the upper three formations. 

 Following description of the localities and sections the Langston 

 question is discussed, which will focus attention on the variability 

 of the lower three Middle Cambrian formations. 



LOCALITIES 



A concise list of localities is desirable to save frequent repetitions, 

 particularly in the fossil and plate descriptions. Consequently the 

 localities from which fossils are described are listed in numerical 

 order. Subsequently the localities will appear again as the sections 



