708 GEOLOGY 



somewhat farther west than no\v in northern California and south- 

 ern Oregon. 



It is probable that the Coast Range of California 1 >oi;an its hist ory 

 at the close of this period, for deformed Jurassic beds (Golden Gate 

 series) underlie the Lower Cretaceous unconformably in the axis of 

 the range; 1 but the movements which gave the Coast Range its 

 present form (modified by erosion) , took place much later. Various 

 other ranges of the west are thought to have begun their history 

 mountains at about the same time. 



Toward the close of the period, much, if not all, of the great 

 Upper Jurassic gulf of the northwestern part of the continent dis- 

 appeared. All in all, the deformations at this time were greater 

 than those which mark the close of most periods. 



FOREIGN JURASSIC 



Europe. Jurassic strata are exposed in many and widely sepa- 

 rated parts of Europe, though for the most part in small areas only. 

 As in the case of older systems, the present distribution of the 

 system at the surface is no measure of its real extent. 



It has been thought that the Jurassic of England is probably con- 

 tinuous with that of France beneath the English Channel, and thence 

 by way of southeastern France, with those parts of the system 

 which appear about the Mediterranean, and by way of Belgium, 

 the Netherlands, and the German lowlands, with those parts which 

 appear in Poland and Russia. In southern Russia, too, the Jurassic 

 beds are probably wide-spread beneath younger formations. The 

 lower part of the system is less extensive than the Middle, and 

 the Middle less wide-spread than the Upper. Progressive suit- 

 mergence was, indeed, one of the features of the period. In this 

 respect, the North American and European continents are in har- 

 mony, but marine formations are much more extended in Kurope. 



In Europe, the subdivision of the system has been carried to a 

 high degree of refinement, but the many zones are grouped into 

 a few principal divisions: 



1 Fairbanks, Jour. Geol., Vol. Ill, pp. ll."> r.o. : m,| Smith. Hull. Qeol 

 Soc. of Am., Vol. V, pp. 257- IT. v 



