704 



( ;i-:<> LOGY 



Montana, 1 Utah, and Colorado, and parts of several other stir 

 (Fig. 476). This is shown by the presence in these states of sedi- 

 mentary beds containing marine fossils of early Upper Jurassic age. 

 The beds are chiefly exposed in the mountains (Wasatch, Uinta, 



Fig. 476.-- Map showing the general relations of land and water in the west- 

 ern part of North America during the later part of the Jurassic period. 

 The black areas represent known areas of Upper Jurassic. The dotted 

 line is the conjectured outline of the bay. (After W. X. Logan 



Black Hills, etc.) where the erosion which followed the uplift and 

 deformation of the strata has discovered their edges. ' 



The avenue through which the sea reached the western interior 



has not been determined, but the fossils of the interior are so unlike 



those of the California?! coast as to lead to the inference that the 



waters of the interior did not come in from the we<t. The identity 



tin- Montana foliix, ('. S. (1ml. Surv. 



'-' For Si. nth Dakota, see Dart on, I'M A MM. H.-j.t.. I'. S. < Iml Surv.. I't. IV. 

 and Ihr i'oiios. I". S. ( ieol. Surv. 



3 In addition to the above folios, U. S. Geol. Surv., see those of Colorado. 



