COLORADO 397 



381. Mount Lewis, La Plata mountains, Colorado. View from the southeast. 



The peak consists of Triassic sandstones, etcetera, with numerous sheets 

 and dikes of diorite-porpbyry, and a small stock of diorite, producing 

 much metamorphism of the strata (No. 272). 



382. Silver peak, La Plata mountains, Colorado. View from the northeast. The 



mountain is a huge irregular mass of diorite-porphyry and diorite in Me- 

 sozoic beds (No. 274). 



383. The Sharkstooth, La Plata mountains, Colorado. The upper exposures are 



of a diorite-porphyry sbeet intruded into Cretaceous shales. The lower 

 cliffs are of a sheet in the Jurassic sbales ; illustrates formation of talus 

 slopes (No. 278). 



384. Mount Wilkinson (or Table mountain), Gunnison county, Colorado. A 



remnant of a complex basalt sheet, resting upon Cretaceous sandstones. 

 "Mesa" type of mountain " (No. 10). 



385. Characteristic timber-line growth of stunted spruces, at an elevation of 12,100 



feet,. head of Cement creek, Gunnison county, Colorado (No. 29). 



386. Meridian lake, near Crested Butte, Gunnison county, Colorado. One mile 



long, 200 to 500 feet wide. Occupies the crest of a ridge of soft Cretaceous 

 shales. Crested Butte mountain in background (No. 50). 



387. Mount Wheatstone, Gunnison county, Colorado (12,543 feet); Upper two- 



thirds of mountain a single mass of coarse porphyry, a laccolite from which 

 all overarching strata have been eroded away ; glacial amphitheaters in 

 upper part (No. 17). 



388. Teocalli mountain, West Brush creek, Gunnison county, Colorado (13,220 



feet). Structure caused by beds of Carboniferous rocks, much metamor- 

 phosed by a large diorite mass behind the mountain (No. 18). 



389. Typical scenery in the Elk mountains, Gunnison county, Colorado. Pearl 



mountain in the center, 13,484 feet ; Brush Creek valley ; timber line at 

 12,000 feet (No. 22). 



390. Castle rock, near Golden, Colorado. A point projecting from the basalt sheet 



of Table mountain. Represents a confused mingling of dense and scoria- 

 ceous lava, presumably near edge of flow (No. 41). 



391. Table mountain, Golden, Colorado. Shows effect of unequal, horizontal 



tabular jointing in dense part of a thick basalt sheet (No. 43). 



392. Spherical sundering in cliff of basalt, northern Table mountain, Golden, 



Colorado. The most distinct spheres are from 1 to 2 feet in diameter, with 

 several concentric shells (No. 1). > 



393. Granite cut by veins of quartz, feldspar, and biotite. In the canyon of 



Animas river, opposite Tenmile creek, Colorado, on railroad track (No. 

 453). 



394. View of Silverton from toll road at east base of Sultan mountain. Shows 



Animas flood plain, mouth of Mineral and Cement creeks, etcetera, Colo- 

 rado (No. 465). 



395. From bench (with cabin) at 11,000 feet, on north side of Mclntyre gulch; 



looking across Red Creek valley, southeast. Shows landslide topography 

 of ridge, north of Corkscrew gulch, Colorado (No. 473). 



396. From knoll near cabin at mouth of Galena Lion gorge; looking east across 



Red creek; to show details of landslide topography on slope between 

 Corkscrew gulch and Red mountain, Colorado (No. 475). 



LVIII— Bur.r,. Gkot,, Soc. Am., Vor,. 13, l'JOl 



