THE MIOCENE PERIOD 



eruptions in the Coast ranges, though farther north vulcanism con- 

 tinued later. The igneous eruptions were accompanied by diastro- 

 phism, which consisted in the readjustment of fault-blocks and folds 

 throughout the Pacific coast region. Even high mountains were 



Fig. 489 Fig. 490 



Fig. 489. Map showing supposed distribution of land and water on the Pacific 



coast during the early Miocene period. (Ralph Arnold.) 



Fig. 490. Map showing supposed distribution of land and water on the Pacific 



coast during the late Miocene period. (Ralph Arnold.) 



developed locally, as shown by the coarseness of the sediments 

 which followed. 



The diastrophism resulted in the extension of the sea, for the 

 Upper Miocene is more widespread than the lower. If a two-fold 



