436 



REPORT OF NATIONAL MUSEUM, 19Q4. 



The classification adopted by Tra.sk was that of the older geologists 

 of his time, the rocks being divided merely into Primary, Secondary, 

 and Tertiary. Although fossils were found, he did not attempt to 

 describe them, and seemed in most cases to fail to realize their value 

 as indicative of any particular geological horizon. His ideas regard- 

 ing metamorphism were somewhat crude. Thus, he stated in his first 

 report: 



■It is a well-known fact that intrusive dikes of trap in passing through limestone 

 will change the calcareous formation to true talcose rocks. 



He divided the State into three divisions: First, a primary or cen- 

 tral district, included between latitude 3S C 30' and 40° north; second, 

 the northern district, included between 40° and 42° north; and third, 

 the southern district, included between 38° 30' and 36° north. The 



rocks of the primary district, he stated, are 

 for the most part primitive, being composed 

 of granite, porphyry, trap, and other allied 

 rocks, of which serpentines form the one 

 important part. The sedimentary rocks of 

 the district were divided into first, argelite 

 (sic) slates; second, conglomerates; and 

 third, sandstones, the last named being re- 

 garded as probably of Miocene age. 



The rocks in the northern district were 

 described as of essentially the same charac- 

 ter, a few minor differences only being noted. 

 The southern district contained many rocks 

 in common with the other two, although 

 there were in addition many basaltic areas. 

 He found a primary limestone in the area between the American and 

 Merced rivers, and evidence of at least three successive periods of 

 upheaval in this portion of the continent. 



In his second report he described the geology of the most elevated 

 portions of the counties of Butte, Sierra, Yuba, Nevada, and Placer; 

 also the more southern counties of San Francisco, Santa Clara, Santa 

 Cruz, Monterey r ; the north part of San Luis Obispo, Tulare, Mari- 

 posa, Tuolumne, Alameda. -Contra Costa, and San Joaquin. During 

 the months of October and November he visited Nevada and Calaveras 

 counties. He pointed out the .presence of post-Pliocene fossils in 

 argillaceous sandstone of the Coast mountains between Point Pinos 

 and Nacismiento River. He divided the Tertiary rocks as below: 



i. — John Boardman Trask. 



