PALEOGEOGRAPHY OF THE MESOZOIC 509 



While the Pacific border of North America was being folded in late 

 Jurassic time, the earth-shell was also invaded by deep-seated igneous 

 rocks (granodiorite) on a large scale. Magmas in great volume were in- 

 truded, forming the great chain of bathyliths now exposed by erosion 

 from Lower California to the Alaskan peninsula. In comparison with 

 this intrusion, Lindgren states that all post-Proterozoic igneous phe- 

 nomena fade into insignificance. The bathylith of the Sierra Nevada is 

 400 miles long, with a maximum width of 80 miles. On the International 

 Boundary there are twelve bathyliths with a width of 350 miles. Farther 

 north appears the Coast Range bathylith, according to Le Roy probably 

 the greatest single intrusive mass known, which extends unbroken for 

 1,100 miles into the southern Yukon country, with a width of from 30 

 to 120 miles. 



SHASTAN TIME 

 (See Figure 5) 



Into the newly made and subsiding trough of the Californian Sea the 

 Pacific Ocean spread, while in British Columbia and Alaska the same 

 waters gradually encroached more and more widely either as a shelf sea 

 or, more probably, another trough — the Columbian trough. The sedi- 

 ments poured into these seas were coarse-grained and were delivered to 

 them by the rivers flowing out of the highlands apparently in the main 

 to the eastward. 



The deposits are essentially sandy shales with thin bands of sandstone, 

 local conglomerates, and rarely thin limestones. The thickness in north- 

 ern California appears to be between 9,000 and 10,000 feet, of which 

 about one-third is of Knoxville time, while the remainder is of Horsetown 

 time. 



The Shastan series of Gabb and. Whitney (1869) is also known in 

 northern Washington and along the Canadian and Alaskan coasts. The 

 deposits are dominantly sandstones with sandy shales, and in most places 

 include from a few hundred to 3,350 feet of lavas, tuffs, and ash beds. In 

 the Queen Charlotte Islands, where these strata have coal beds, the depth 

 is estimated at 9,500 feet, and elsewhere, although somewhat less, the 

 thicknesses are rarely as low as 2,000 feet. 



The sands and muds of the Shastan series in most places overlap un- 

 conformably the older and often metamorphosed formations. This un- 

 conformity is sometimes marked, as in the Klamath Mountains and the 

 Coast Range," or is of the erosional type. However, there are also discon- 

 formable contacts. The faunas, as pointed out by Stanton, are of the 

 Indo-Pacific realm and are remarkably distinct throughout from those 



