GEOLOGIC RECORD OF CALIFORNIA 217 



very much the same part in the geologic history of North America 

 as the ancient Mediterranean or Tethys did in the history of Europe, 

 though on a much smaller scale, since it was epicontinental, and 

 not intercontinental. The Cambrian, Silurian, and Devonian sedi- 

 ments of California are mere fragments of little area and thickness, 

 representing only a small part of the entire time of those ages. The 

 Carboniferous, however, is fairly complete, all three major divisions 

 being fully represented by marine faunas. The Triassic period is 

 well represented; the Lower Triassic is nearly as good as the stand- 

 ard American section of Idaho; the Middle Triassic has both of the 

 greater divisions, although the main portion is not nearly so complete 

 as the standard section of the West Humboldt Range in Nevada. 

 The Upper Triassic of California is the standard for this epoch in 

 America, and compares very favorably with the rest of the world in 

 the richness of its faunas, and the completeness of the record. The 

 Jurassic section of the Great Basin Sea is the most complete in the 

 United States, having portions of each stage from Lias to Kelloway, 

 inclusive; but it is fragmentary, the faunas being poorly preserved 

 and scanty. It is not comparable with the Jurassic record of Alaska 

 and British Columbia, and nowhere approaching that of South Amer- 

 ica. With this epoch the marine column of the Great Basin ends 

 abruptly, as the sea was obliterated at the beginning of the Cordilleran 

 revolution. 



Pacific record. — The marine record of California from the bottom 

 of the Upper Jurassic through the Quaternary was kept exclusively 

 by the Pacific Ocean. This was divided between two provinces," 

 or areas of sedimentation, the Sierra Nevada, and the Coast Ranges, 

 but the distribution was not balanced. The Pacific province is one 

 of the great geosynclines, with sediments approximating seventy 

 thousand feet in thickness, and undergoing subsidence more or less 

 continuously, though spasmodically, from the Triassic onward, 

 interrupted by great periods of orogenic activity. This is a part of 

 that grand structural feature of the continent of which the Great 

 Valley, the Gulf of California, the Willamette Valley, and Puget 

 Sound are mere remnants. 



The recognizable Paleozoic and early Mesozoic sediments are 

 confined to the Sierra Nevada, while the Cretaceous and Tertiary 



