120 



University of California. 



[Vol. 2. 



Dynamic History — 



Granitic Intrusion 



Subsequent Movements 



149 

 149 

 152 

 152 

 152 

 152 



Summary and Conclusion. 



Granite 



Ancient Crust 



Miocene 



INTRODUCTION. 



General Statemeitt. — One peculiarity of the western coast of the 

 United States south of Puget Sound is the comparatively unbroken 

 regularity of its shore-lines. Few islands or inlets fringe the con- 

 tinental border for many hundreds of miles, and the student of 

 geology here does not often have the advantages of a much- 

 dissected coast. 



The coast of California furnishes at least a few exceptions to the 

 rule, among which may be enumerated the peninsula of Point Reyes. 

 This body of land is almost severed from the mainland in a manner 

 that at once challenges the attention. It is roughly triangular in 

 outline, about sixty-five square miles in area, and lies some thirty 

 miles north of San Francisco and the Golden Gate. 



The study of its geology was undertaken at the suggestion 

 of Professor Lawson, to whom we are indebted for much that 

 is known of the physiography of the coast of California. The field 

 offers some unusual advantages for the study of the oscillatory 

 movements that have affected the coast in Neocene and later times, 

 the records of which are preserved in terraces and marine deposits. 

 It embraces also the northern termination of a granitic massif that 

 follows the coast in a series of ranges for more than two hundred 

 miles. The relationship of these granites to others of remoter por- 

 tions of the coast, for example those of the Klamath Mountains and 

 of southern California, has not yet been ascertained and would 

 richly reward investigation. 



It is probable that many of the movements that have disturbed 

 the region west of the great valley of California have had direct 

 reference to this granitic axis, which has accordingly, therefore, been 

 implicated causally in many of the structural phenomena of the 

 Coast Ranges. 



