I 22 



University of California. 



[Vol. 2. 



The work of the State Survey, however, was too brief and widely 

 distributed to give to this section more than a passing notice. 



Following this brief description and the little information to be 

 gathered from the reports of the Coast and Geodetic Survey, the 

 State Mining Bureau in its geological map of the state shows only 

 approximately the distribution of the formations on this portion 

 of the coast. 



In 1894 Professor Lawson, on a tour along the northern coasts 

 of California, visited the peninsula, and has discussed 1 some of the 

 more important matters of its physiography. The field-work for the 

 present paper was done at intervals in the winter of 1896-7. Its 

 writing and the necessary laboratory study was done meanwhile at 

 the University of California with the advice and assistance of Pro- 

 fessor Lawson. 



GRANITE. 



There are not many distinct formations occurring on the portion 

 of the peninsula covered by this work, which are of large areal 

 extent. The more important of them are the granites and the 

 Miocene sedimentary series. But besides these there are some 

 smaller areas of metamorphic limestone and quartzites, with a few 

 patches of schists, and some recent deposits of coarse alluvial 

 detritus and of aeolian sands. 



Areas. — Granite occurs upon the peninsula in three areas, two 

 of which are more or less connected although they show some 

 general petrographic differences. 



At the northern extremity granites occupy almost the whole 

 of the ridge from Tomales Point southward for a distance of about 

 five miles. Here they are overlain by the Miocene deposits and 

 patches of drifted sands. At White Gulch, on the Pierce Ranch, 

 the granite is covered by a moderate thickness of yellowish sandstone 

 and white shale. Northward the cliffs on both sides of the point 

 are almost wholly of granite. Southward on the ocean side, opposite 

 the Skinner Ranch, the granite hills of the long, narrow point drop 

 suddenly off southward to the level of a low terrace or rolling plain 



'Bull. Dept. Geol. Univ. Cal., Vol. 1, pp. 245, 264. 



