THE GEOLOGIC RECORD OF CALIFORNIA 



JAMES PERRIN SMITH 



Stanford University, Cal. 



The geologic record of California is exceedingly complete for a 

 single geographic region, because of the two ancient and persistent 

 seas that covered some portion of its surface during each geologic 

 period. These seas were the Pacific Ocean and the Great Basin Sea. 



The geologic history of California is given below chiefly in the 

 form of tables, for the sake of brevity, and without a discussion of 

 the faunas and floras of the various formations, since that would 

 extend the paper beyond the size intended. Such a discussion is 

 reserved for a later paper. 



The tables here given have been based on a critical study of all 

 the papers on the stratigraphy of California, and on the writer's 

 experience in this field for a period of seventeen years, of which a 

 large part has been spent in field study. 



Great Basin Sea. — The older portion of the geologic record, from 

 the Cambrian to the top of the Middle Jurassic, has been preserved 

 chiefly in the sediments of the Great Basin Sea, while during those 

 ages that part of California which was afterward covered by the 

 Pacific Ocean was either above water, or has had its sediments so 

 much metamorphosed that their age is not positively determinable. 



The Great Basin Sea of Paleozoic and early Mesozoic time covered 

 approximately the area of the Great Basin of the present age, some- 

 times more, and sometimes less, dwindling away gradually from the 

 noble expanse of the Carboniferous Sea to the shrunken remnant in 

 early Mesozoic time. This basin at all times was directly connected 

 with the Pacific Ocean, by a broad passage to the northwest; and 

 during a part of the Paleozoic, especially during the period of the 

 Coal Measures, it was joined to the Mississippian Sea. At all other 

 times it was exclusively western, and the marine Triassic and Jurassic 

 history of the United States is its peculiar property. It has played 



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