CORRELATION OF FORMATIONS 487 



Lake Como, bat the general aspect of the material collected by Doctor Walcott is 

 sugge3tive of Jurassic, rather than of Triassie relations. This might very well 

 happen, notwithstanding the horizon be definitely proved by stratigraphic and 

 other evidence to be of Triassie age, as other instances of pioneer faunas and over- 

 lapping contingents are not uncommon " (10a). 



Associated with the fish remains there were found several representa- 

 tives of other classes of animal life, concerning which Doctor Eastman 

 has given me the following comments, pending more careful investiga- 

 tion : c< There is one ammonite in the collection, or rather a portion of 

 the outer volution of one, which is very suggestive of the Liassic Arietidae, 

 and in the opinion of Doctor Jackson and Mr Shimer, who have exam- 

 ined it, does not seem to belong to the class of forms known from the 

 Pacific Coast Trias." There are numerous Estheria in. the collection and 

 fragmentary saurian teeth, but whether of crocodilian or ichthyosaurian 

 forms Doctor Eastman is unable to determine. 



From the statements of Eastman it appears that the Kanab fauna 

 obtained by Walcott is unique and raises several interesting problems 

 for solution. The fossil-bearing strata were traced by Walcott from the 

 Kanab eastward to the Colorado river, and thus are known to occur not 

 far from the area in which the Saurian fauna of the Little Colorado was 

 obtained b}' Ward and Brown, both faunas belonging apparently to the 

 Shinarump group. The relations of the two fossiliferous horizons areas 

 yet quite unknown. From the stratigraphic standpoint it is difficult to 

 see how the Kanab fossils can possibly be of Jurassic age f unless there 

 are complications, hitherto wholly unsuspected, in the great section of 

 the Plateau country. 



NORTHEASTERN UTAH AND NORTHWESTERN COLORADO 



The Triassie and Jurassic formations of the eastern Uinta mountains, 

 as exposed near Green river and in the Yam pa plateau, have been 

 described by Powell, King, Emmons, and White. Powell (36) applied 

 the divisions of the Plateau county to this northern field. King (24) 

 and Emmons (16) described the formations in terms very similar to those 

 of Powell. They mention a greenish limestone occurring below the red 

 sandstone (Vermilion Cliff) in which a single shell, Natica lelia, was found 

 (24, pages 259, 263, 264). All these geologists referred the White Cliff 

 sandstone to the Triassie, recognizing as Jurassic only the Flaming Gorge 

 group of Powell, with its marine fauna in the basal limestone. 



The Hay den Survey geologist working in this area, Dr C. A. White, 

 considered the section between the Carboniferous and Cretaceous as 

 belonging to one system, of continuous sedimentation, and as probably 

 Jurassic for the most part, and applied the term Jura-Trias to the 



