224 



HISTORICAL GEOLOGY 



Humboldt Range of western Nevada, were also probably upraised 

 toward the close of the Jurassic. 



The great arm of the sea or gulf which spread over the western 

 interior region late in the Jurassic was drained as a result of these 

 crust al disturbances. Hence we learn that all of North America 

 except much of the western margin was dry land at the close of the 

 Jurassic period. 



Foreign Jurassic 



Europe. — The marine transgression which, in late Triassic 

 time, resulted in the submergence of the great salt lakes and other 



lb 













• ,' • •jls* - • • '•/- 



v S J' 



/■'. ') y( 



^f—^ 









'^li^if 



SfS 







^ • ' •:') ■).'. 





x-v'-v 



V^-=^==^ 



^ : <f 



\y ' V^- 



'dtj^. 





Fig. 134 

 Sketch map showing the relations of land and water in 

 Europe during late Jurassic time. (Slightly modified 

 after De Lapparent.) 



basins of central and western Europe, continued into the Jurassic. 

 Even in the early (Lias) part of the period the sea covered consider- 

 able areas in western, central, and southern portions of the con- 

 tinent. The strata are mostly typical shallow sea sediments, 

 though some coal-forming swamps existed around the sea borders 

 in central Europe. These early Jurassic strata are usually conform- 

 able upon and not sharply separated from the underlying Triassic. 



