THE PLIOCENE PERIOD. 



317 



be a connection between them, it was probably not in the simple and 

 commonly accepted sense. 



The volcanic activity of preceding periods continued into the Plio- 

















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Fig. 464. — Map and section of the Marysville, Cal., volcano; E7, Eocene (Tejon for- 

 mation); jvi f Miocene (lone formation); Q/, Quaternary (river gravels); iVo, 

 andesite, iVr, rhyolite, and iVa£, andesite tuff. Area of the map about 100 square 

 miles. (Lindgren and Turner, Marysville, Cal. folio, U. S. Geol. Surv.) 



cene, and became somewhat pronounced near the end of the period, 

 in different parts of the Cordilleran system. Some of the late igneous 

 formations of the Sierras, and perhaps of northern California, 1 belonged 

 to this time, and probably some of those of nearly or quite every other 

 state west of the Rocky mountains. Many of the prominent volcanic 



1 Hershev. Jour, of Geol., Vol. X, pp. 377-392. 



