PHOTOGRAPHS DONATED BY U. S. GEOLOGICAL SURVEY. 383 



1303 (46). Silver lake, Monte Oisto (see 45). Near view of Silver lake, showing 



the outlet and the surrounding cliffs of porphyrite. 



1304 (49). Looking down Twin lakes, Monte Cristo. General view of Twin lakes 



about three miles southeast of Monte Cristo. These lakes occupy 

 basins of craters, the largest being about half a mile in length. The 

 rock surrounding them in the foreground, on the right of the picture, 

 is granite, while much of the farther side of the lake and the fore- 

 ground in the extreme left is volcanic breccia. Spherulitie rhyolite 

 occurs at the east end. The higher cliffs in the vicinity are largely 

 made up of breccia with granite fragments. The foreground exhibits 

 roches moutonnees. 



1305 (51). Upper Twin lake from the east end, Monte Cristo (see 49). View from 



the east end of upper Twin lake. The cliff on the right is granite, 

 while the talus in the foreground is composed of blocks of volcanic 

 breccia. Immediately behind the camera, cliffs of breccia rise about 

 2,500 feet to the summit of Glacier peak (see 41 and 43). 



1306 (52). Volcanic breccia of Twin Lake crater, Monte Cristo (see number 41). 



The camera stands on the arete between Twin lakes and the " '76" 

 amphitheater, looking into the latter. The breccia on the right was 

 erupted from Twin lakes, and is in immediate contact with the granite, 

 of which it contains fragments. 



1307 (54). Sauk mountain from near Sauk, Washington. It rises abruptly on the 



western bank of the Skagit river. It is an old volcanic vent, prob- 

 ably represented by a lake which now lies in a deep basin near the 

 summit. The elevation is about 5,800 feet, and the volcanics are 

 erupted through a mass of iron-bearing schist and limestone. 



1308 (60). Landslide crack, Sauk mountain. On the left of the view the descent 



is precipitous for 500 or 600 feet. ' The crack in the middle ground 

 on the right is evidently due to an outward movement of the rock 

 mass toward the cliff, but is now filled with debris to within a few 

 feet of the top. 



1309 (63). Limestone, Baker River canyon, Washington. View on Baker river 



half a mile above its junction with the Skagit. The river flows 

 through a canyon which it enters from a broader valley carved in 

 shales. The rocks of the canyon are a highly crystalline limestone 

 dipping northwest. Crinoids have been discovered and other fossils 

 may be expected. These are the oldest known rocks in Washington. 



1310 (65). Salmon fishing and limestone, Baker River canyon, Washington (see 63). 



View looking down Baker River canyon toward the Skagit. The 

 masses of limestone in the foreground are among those in which 

 crinoids were found. The high stage of the river has forced the sal- 

 mon into the eddies among the boulders, and the fisherman, taking 

 advantage of their position, is able to catch them at will. 



Thirteen views presented by the U. S. Geological Survey ( G. K. Gilbert) 

 Size, 4£ by 7? inches. Figures in parentheses are original negative numbers 



1311 (35). Group of Tepee buttes north of Nepesta, Pueblo county, Colorado. 

 I/VII— Bull. Geol. Soc. Am., Vol. 8, 1896 



