360 F. L. Ransome — Lava Flows of California. 



ments up to the group of peaks known as the Dardanelles. 

 These elevations, consisting of masses of nearly horizontal 

 volcanic material, with a total thickness of from 1200 to 1900 

 feet, resting upon the worn granitic basement, exhibit an 

 interesting "variety of lavas. The westernmost peak of the 

 group was the only one actually visited, and the sequence of 

 the lavas there exposed is as follows: Resting immediately 

 upon the granite on the southwest side of the west Darda- 

 nelle is a comparatively thin bed of rhyolitic tuff. This is in 

 turn covered by several flows of olivine basalt aggregating at 

 least 300 feet in thickness. Above the olivine basalt lies the 

 Table Mountain flow, which here attains a thickness of about 

 500 feet. Its exposed edges break away in imposing columnar 

 cliffs which give the peak its striking outline. At the base 

 of the cliff there is usually a heavy tains of fallen columns, 

 concealing the contact with the underlying olivine basalt. 

 Above the Table Mountain flow, and forming the extreme 

 summit of the west Dardanelle, are portions of the second and 

 third latite flows whose general occurrences are next to be 

 described. 



The Biotite-augite-latite. — The rock of the second flow is 

 readily distinguished from that of the flows that followed 

 and preceded it by the presence of abundant megascopic 

 crystals of biotite, and by other characteristic lithological 

 features. It occurs in relatively thin masses, rarely exceeding 

 50 feet in thickness, usually resting upon the Table Mountain 

 flow, but frequently occurring alone as the only local represen- 

 tative of the latitic series. Like the earlier flow, it fol- 

 lowed the old channel already described, but is not known to 

 have extended farther than a point about 4 miles south of Big 

 Trees. In marked distinction from what is known of the 

 earlier and later latite eruptions, the lava of this out- 

 burst found its way into other channels besides the main one 

 previously outlined. Thus small patches of the biotite-augite- 

 latite are found north of Big Trees, and south of the 

 Middle Fork of the Stanislaus. On the summit of the west 

 Dardanelle this flow is about 50 feet in thickness, and lies 

 between the Table Mountain flow and the one next to be 

 described. 



The Dardanelle Flow. — This, the last product which has 

 been preserved of the activity of the latite vents, has 

 received its designation from the fact that a remnant of the 

 flow forms the extreme summit of the west Dardanelle, and is 

 there typically developed, with a thickness of about 150 feet. 

 Like the first flow, its occurrence is limited, as far as known, 

 to the main Neocene channel, and its remnants have not been 

 detected below the point, about 4 miles south of Big Trees, 



