STRATIGRAPHIC SERIES 521 



As a basis for comparison and discussion, the chief relevant points in 

 the geology of the western Uintas are given below. The accompanying 

 detailed map of the headwaters of the Du Chesne (figure 2) is based on 

 the topographic sheets of the United States Geological Survey, with some 

 minor details added from personal observation. 



The stratigraphic Series 



1. There are no formations exposed below the great sandstone and 

 quartzite series forming the core of the mountain range; but this for- 

 mation is very thick, perhaps 12,000 to 14,000 feet, as estimated by the 

 early investigators. Neither its upper nor its lower beds are to be seen 

 in this area. A great fault paralleling the range cuts the quartzites ab- 

 ruptly, and from this fault southward the succession of younger strata is 

 continuous. Furthermore, the lowest of them is very suggestive in con- 

 nection with the question of correlation at issue. The fact that they are 

 not seriously regarded in former discussions would seem to indicate that 

 they do not appear in other areas because of the general faulting; or it 

 may be that, being mainly offshore deposits, they are represented else- 

 where by equivalents of very different character. 



2. The beds next to the fault line are black pyritiferous shales. They 

 are well exposed at the mouth of Iron creek. Their thickness is unknown. 



3. On these shales lie brown, shaly sandstones, calcareous shales, and 

 sandstones which, with the pyritiferous shales, make a total thickness of 

 about 3,000 feet. 



4. Next above is a very coarse pebbly sandstone or conglomeratic 

 quartzite less than 1,000 feet thick. Numbers 2, 3, and 4* are non-fos- 

 siliferous. 



5. A great limestone formation is well marked throughout the Uintas- 

 It is dense and recrystallized into a marble toward the base, but is close 

 grained, bluish, and fossil-bearing in the middle and upper zones. It 

 passes in its upper third into calcareous, argillaceous, and sandy shales 

 and is capped by a limestone that is very cherty. The shales carry 

 abundant fossils of Carboniferous types. 



There is a break, discussed in a later paragraph, between this and the 

 succeeding formation. 



6. A basal conglomerate merging into a quartzite and shaly sandstone 

 1,000 feet. 



♦All of these beds are non-fos-uliferons, and, although they are so well developed, seem to have 

 been largely neglected in the interpretation of stratigraphy. The general statement is made by 

 the Fortieth Parallel reports that the basal quartzite of the Uintas is succeeded by gray lime- 

 stone, calcareous sand rock, thin calcareous- shale beds, and cherty limestone, fossiliferous from 

 bottom to top. 



