'ORE DETOSITS. 225 



are probably far older The distribution of volcanic rocks in the belt 

 where they occur, however, is very irregular, corresponding to the irregu- 

 larity of the entire chain of mountains called the Coast llanges. 



A close connection exists between the structural and historical geology 

 of tlie quicksilver belt and deposits of cinnabar, as will appear in subse- 

 quent chapters. Here it is sufficient to say that ore deposition has taken 

 place only since the earlier volcanic eruptions and seems in all cases to 

 have Ijcen brought about by heated solutions of volcanic origin. Cinna- 

 bar occurs in almost every variety of the rocks found in the Coast Ranges, 

 and the age and origin of the inclosing rocks do not seem to have affected 

 the deposition of ore in any way. 

 MON XIII 15 



