MESOZOIC TIME — TRIASSIC AND JURASSIC. 811 



dioryte in dikes would be a natural result of friction along fault-planes cutting through 

 such an underlying crystalline mass. The extrusion of igneous rocks accompanying 

 mountain-making has been a common fact over the summit region of the Rocky 

 Mountains ; an example occurs in the Wasatch, which has, like the Sierra, a "granite" 

 core. 



Had the granitoid mass been a result of deep-seated eruption at the time of the 

 upturning, or at any later date, or earlier, it would have come to the surface in great 

 fissures ; for fissures, as the result of fractures, give exit to the confined liquid rock of the 

 earth's depths. Moreover, liquid dioryte is identical with andesyte lava, and liquid 

 granite with rhyolyte ; and if ejected at the time supposed, it should show evidence of 

 the chilling effect of the relatively cold Sierra rocks along their contacts with them. 

 Instead of this, the rock of the core is well crystallized to its surface, and has a coarseness 

 of crystalline texture which indicates extremely slow cooling. Neither is the existence of 

 auriferous quartz veins in the granite positive evidence of its recent origin ; for the granite 

 of Pike's Peak, according to W. Cross, contains sandstone dikes (Feb., 1894). Further, 

 if the ridges of crystalline rock in California and to the north are all eruptive and of late 

 Mesozoic age, as is urged, and the emergence at the close of the Triassic is the earliest of 

 much importance, there is no sufficient source for the sediments of which the successive 

 sedimentary rocks were made. They could not have come from the eastward ; for the 

 oceanic currents of the Pacific border are now, and must have been in early time, from the 

 northwest ; and besides, the ridges of the Pacific border are north or northwest in coui'se. 

 Moreover, oceanic currents are relatively feeble transporters, and find their material for 

 rock making near at hand. 



Such a mass of crystalline rock having irregular or indefinite outline has received the 

 name of bathylite. [Bathylith would be a better name, as it is here used for a mass, not a 

 kind, of rock. ) It has one mode of origin that is consistent with indefiniteness of outline. 

 When a pile of deposits, 30,000 feet or more in depth, has beds in its lower portion that admit 

 of fusion under the action of the heat producing metamorphism, the melted material 

 would make a mass of indefinite outline. The fusion, under the same circumstances, of 

 the rocks immediately below the pile, might add to the melted mass or be its chief source. 

 Here is fusion unbounded by the walls of a fissure. This was common, as has been else- 

 where remarked, in Archsean time. There is no sufficient evidence that it occurred 

 during the Sierra upturning at the close of the Jurassic, or in any other part of Mesozoic 

 time. 



The pre-Cretaceous age of the metamorphic rocks of the Coast Eange 

 has been urged by Fairbanks (1892). This view is held also to some extent 

 by Turner and Diller ; and the latter states that the Coast Eange was up- 

 heaved with the Sierra Nevada at the close of the Jurassic. This conclusion 

 is drawn from the fact that the Cretaceous thins out, both to the eastward 

 and westward of the Sacramento valley, and that the later beds have their 

 greatest extension in these directions. 



The Cascade Range appears, from its position, to be part of the Sierra 

 system. Becker reports that the same class of metamorphic rocks characterizes 

 the portion of it in Oregon where not buried beneath later volcanic ejections. 

 The Blue Mountains of Oregon also have their Jurassic rocks, and were 

 probably among the results of the post- Jurassic upturning. 



In the Plateau Belt, or that of the Great Basin, near Carson Lake, the 

 West-Humboldt range, according to King, was made at this time. It includes 

 several ridges between 117^" W. and 119° W. ; and the thickness of the 



