400 Scientific Intelligence. 



Sierra Nevada Range. From the facts it follows that the Sierra 

 and Coast Ranges experienced upheaval long before the era of 

 the Chico group ; and that the same disturbance which deter- 

 mined the existence of the Coast Ranges added the gold belt 

 proper to the Sierra Nevada ; and that probably " a portion at 

 least of the Cascade Range was elevated and metamorphosed at 

 the same time. Consequently, before the Chico era there was a 

 sinking," admitting the ocean over a great part of the Coast 

 Ranges and over considerable areas at the base of the Sierra for the 

 later depositions. During the Pliocene very little of either range 

 was below water. 



The following paragraph is from pages 22, 23 of the paper. 



" I think it may be assei'ted, as a result of all the geological 

 work done from the Rocky Mountains to the Pacific, that there has 

 been, throughout geological time, a definite tendency in the struc- 

 tural development of this area. The geologist of the fortieth 

 parallel exploration showed that a fault began upon the west 

 flank of the Wahsatch in the Archaean, the same fault which Mr. 

 Gilbert has traced as still in progress. The last-named geologist 

 has also detected a similar fracture on the east side of the lower 

 portion of the Sierra. The eastern portion of the Great Basin was 

 lifted above the surface of the ocean after the close of the Carbon- 

 iferous, the western portion of the same area followed before the 

 Cretaceous, and at one or both of these epochs the country was 

 laterally compressed, an action no doubt closely connected with 

 the progress of the great faults. About the time of the Neoco- 

 mian, California experienced an east and west compression, and 

 again, following the Miocene, was an uplift throwing the horizon- 

 tal strata of the coast into north and south folds. From the 

 Wahsatch to the Pacific Coast there thus appears to have been a 

 recurrent, if not a constant tendency to lateral compression, in 

 substantially one and the same direction. Now Dr. White points 

 out that an extraordinary difference has existed between the 

 marine fauna of the Pacific Coast and that of the waters east of 

 the Sierra from a time prior to the Cretaceous onward, and hence 

 that a land barrier must throughout have occupied substantially 

 the position of the Sierra Nevada, which must therefore have experi- 

 enced repeated upheavals to compensate for constant erosion. 

 There are also said to be some paleontological grounds for sup- 

 posing at least a partial separation of these areas during the Car- 

 boniferous. This supposition is in entire accord not only with 

 the structural analogies of the region but with the detailed 

 observations of Mr. Clarence King* and his colleagues, who were 

 led to infer the existence of a continental area during the Paleo- 

 zoic, west of long. 117°30', lat. 40°. Such a range as the Sierra, 

 though partaking in the general compression and movement of 

 the whole country, must offer a tremendous resistance; and, at any 

 one of the active periods during which the physical conditions 

 permitted contortion of strata along the western flank of the 



* Systematic Geology, p. 534. 



