416 Diller and Sckuchert — Devonian Rocks in California. 



Before seeing these Serpulse atolls and reefs I had come to the 

 conclusion that the Hogsty Reef atoll (Bahamas) may have been 

 formed in the same way, by the mechanical action of the surf over 



a reef which was in great 

 part a veneer on the seol- 

 ian ledges of its bank, the 

 scour of the mass of water 

 poured into the lagoon 

 gradually hollowing i t 

 out. The Hogsty reef is 

 about 4^ miles long and 

 .,-'--'' (j_J C -) t 2£ miles wide, the depth 



'\ J 3, ^V? ^l (<■ of the lagoon varies from 



2 .to 3 fathoms off the 

 platform at the weather 

 extremity to 7 fathoms at the entrance to the lagoon. That 

 water falling can dig out to such a depth is of course well 

 known. On a small scale this can be observed at the foot of 

 every sluice of a draining or irrigating ditch. How deep can 

 it act on a large scale so as to produce an effective result? 



Fig. "7. 



L. — Discovery of Devonian, Rocks in California; 

 by J. S. Diller and Charles Schuchert. 



Art. 



Faet I. 



Dr. J. B. Trask^ was the first to definitely determine by 

 paleontological evidence the geological age of any portion of 

 the auriferous slates of California. He recognized the Car- 

 boniferous on the McCloud River. The Geological Survey of 

 California under Prof. Whitney :£ found the Carboniferous in 

 other localities and discovered the Jurassic and Triassic rocks 

 of Mariposa and Plumas Counties. Dr. C. A. White sug- 

 gested that a part of the Auriferous slates are older than the 

 Carboniferous.§ 



The present writer, from a study of the structure of the 

 northern end of the Sierra Nevada concluded as follows : " The 

 stratigraphic relations are such as to render it very probable 

 that there is a great thickness of paleozoic strata exposed in 

 the region and that a large part of the gold-bearing slates are 



* Published with the permission of the Director of the U. S. Geological Sur- 

 vey. Read before the Geological Society of Washington, D. C, April 25, 1894. 



f Report on the Geology of the Coast Mountains, State Senate of California, 

 Document No. 14, Session of 1855, p. 50. 



\ The Auriferous Gravels of the Sierra Nevada of California, p. 34, etc. 



§ U. S. Geological Survey Bulletin, No. 15, p. 25. See. also, D. S. G. S. Bull. 

 19, p. 21, by G. F. Becker. 



