370 J. S. DILLER — GEOLOGY OF THE TAYLORVILLE REGION. 



Part I — The Geologic Column. 



INTRODUCTION. 



Reconnoissance of the California Survey. — The Taylorville region of 

 Plumas county. California, lies in the Sierra Nevada immediately north 

 of the fortieth parallel. Reconnoitering parties of the ( 'alit'ornia geologi- 

 cal survey passed through the region in 1861 and 1863* and observed 

 slates and sandstones, sometimes but little metamorphosed, also hard 

 lava and granitic masses, and reported that " This part of the country is 

 principally occupied by the metamorphic rocks over an area of about 

 thirty miles in diameter." It is "Almost entirely surrounded by vol- 

 canic materials, the great lava streams which have come down from 

 Lassen peak on the north and Pilot peak on the south uniting with the 

 volcanic crest of the Sierra so as to cover the slates around three-quarters 

 of the circumference of the circle." The state survey party in 1863 con- 

 sisted of Messrs Brewer and King, who made two very important discov- 

 eries of fossils, the first near Mormon station, in the canyon about midway 

 on the road from Indian to Genesee valley, where a considerable number 

 of specimens of various genera and species were obtained. They were 

 found principally on the spurs of rocks coming down from the north 

 and in the canyons between them. According to Professor Whitney, the 

 rock is a rather tine grained metamorphic sandstone, and portions of 

 it are of a deep red color, resembling in appearance much of the Old 

 Red or Devonian sandstone in England and on the continent. In places 

 it is so much changed that the fossils have become nearly or even quite 

 obliterated, hut a number of species were obtained ina sufficiently good 

 state of preservation to be determined. The specimens collected were 

 referred to Mr. Meek for examination, and were considered by him to be 

 almost certainly of Jurassic age.f 



The second important locality of fossils discovered by Brewer and King- 

 in this region is on the northern side of < renesee valley, between the main 

 belt of limestone and the granite. At this point there is a limited patch 

 of calcareous slates containing quite a number of fossils. Some of them 

 are very well preserved. Professor Whitney says these fossils belong to 

 the Triassic series and prove clearly the existence at this point of the 

 same formation which is so well developed in the Humboldt mining 



♦Geological Survey of California, vol. i. 1865, p. 307 The explorations were made by Mr.Ashburner 

 in 1861 ami by Messrs Brewer ami King in 1863, under the direction oi Professor Whitney, state 

 geologist. The place called " Elizabethtown " in the above report is supposed to have i n Tay- 

 lorville, as it i< on the waj to Genesee valley, aboui eleven miles from Quincy, from which it is 

 separated by a prominent i noun lain. Elizabethtown was much nearer Quincy. 



f Ibid., p. 308. 



