F. L. Eansome — Lava Flows of California. 357 



indicated, and the areas of 

 latite are drawn with ap- 

 proximate outlines, subject 

 to future revision. A similar 

 explanation should also be 

 made in regard to the corner 

 of the map lying east of 

 longitude 120°, which is a 

 part of the Dardanelles sheet. 

 The work in this portion of 

 the area was limited to a rapid 

 reconnoissance before the 

 completion of the topographic 

 map. 



The elevations, in the region 

 studied, range from a general 

 altitude of about 500 feet, near 

 Knight's Ferry, to 9529 feet 

 on the culminating summit of 

 the group of peaks, in the 

 eastern corner of the area, 

 known as the Dardanelles, cor- 

 responding to an average 

 grade of 150 feet per mile. 

 As a whole, this area is prac- 

 tically destitute of alluvial 

 valley-bottoms, and is drained 

 by streams of torrential char- 

 acter. It is traversed from 

 end to end by the young, con- 

 sequent Stanislaus River, in- 

 cluding its two principal 

 branches the North and Mid- 

 dle Forks, and may be re- 

 garded as a thoroughly typical 

 transverse strip of the great 

 tilted and dissected peneplain 

 which forms the western slope 

 of the Sierra Nevada. The 

 rocks upon which this rather 

 uneven peneplain lias been 

 carved are those of the so- 

 called "Bed-rock Series" of 

 the Gold Belt folios, compris- 

 ing rocks of Jurassic and pro- 

 Jurassic age, with later intru- 

 sive masses, and consisting in 



