904 W. LINDGREN—F. H. KNOWLTON 



the history of the coast ranges in later geological times would be 

 as follows : 



Miocene depression. 



Post-Miocene uplift and long period of erosion. 



Pliocene depression ; filling of valleys and truncation of the mountain 



to an approximate peneplain ; archipelagic coast line. 

 Pleistocene uplift ; beach lines. 



The age of the beds has been determined by their molluscan 

 remains, a line of evidence not altogether satisfactory where 

 Tertiary and recent beds are concerned as has been pointed out 

 among others by Professor Lawson' and also by Professor W. H. 

 Dall.= 



The question now arises how the beds along the foot of the 

 Sierra Nevada should be correlated with the beds of the coast 

 ranges. Dr. Lawson, without hesitation, correlates the Merced 

 series with the auriferous gravels of the Sierra Nevada, 3 accept- 

 ing Whitney's determination of them as Pliocene. 



It has been shown in the preceding pages that the upper part 

 of the ante-volcanic auriferous gravels correspond to the lone 

 formation, and both have on palaeobotanic grounds been referred 

 to the upper Miocene. It has also been shown that the flora of 

 the volcanic period very closely resembles that of the lone for- 

 mation. A very similar flora has been described by Lesquereux 

 from Corral Hollow and Kirker Pass near Mount Diablo, on the 

 western side of the valley. "^ The beds rest in apparent conform- 

 ity on Miocene carrying Ostrea tita?i Conrad, are associated with 

 molluscan forms determined by Gabb as Pliocene from the 

 twenty-one species identified ; and are capped by detrital ande- 

 ■sitic beds. 



The characteristic feature of this flora of the lone and the 

 auriferous gravels is that it is related in its general characters to 

 that of a subtropical moist region analogous to the northern 

 coast of the Gulf of Mexico. It contains genera such as 



'Bull. Dept. Geol. Univ. Calif., Vol. I, p. 57. 



= Bull. 84, U. S. G. S., p. 195. 



3 Bull Dep. Geol. Univ. Calif., Vol. I, No. 4, p. 157. See also Vol. I, No. i, p. 56. 



4H. V^. Turner, Geol. Soc. Am. Bull., Vol. II, pp. 383-402. 



