PART II. DETAILED DESCRIPTIONS OF SPECIAL AREAS AND INDIVIDUAL 
MINES, 
INTRODUCTION. 
The following descriptions are arranged in general conformity to 
i geographical plan. The mines in the Silver Lake Basin, in the 
loutheastern pari of the quadrangle, are first described. Proceeding 
lorthward, other groups are taken up, in the eastern and northeast- 
ern portions of the area. Then follow, successively, accounts of 
nines in the northern, northwestern, western, and southern districts, 
md, finally, descriptions of the Cement Creek ore deposits in the 
touthwest-central part of the quadrangle. 
LODES OF SILVER LAKE BASIN. 
General fen tin- < s. —The basin in which Silver Lake lies is a typical 
Ligh cirque of a kind common in the San Juan Mountains. Its rocky, 
lummocky floor, with an altitude between 12,000 and 12,500 feet, is 
aclosed on three sides by cliffs and precipitous slopes culminating 
n Kendall and Little Gianl peaks, which attain altitudes of over 
3,400 feet. The basin opens to the north-northwest, and its sloping 
(oor is terminated, at an altitude of aboul L2,000 feet, by precipices 
rhich plunge down to the talus-covered bottom of Arrastra Gulch. 
iilver Lake, 1 a characteristic mountain tarn, occupies a depression of 
onsiderable depth, excavated by glacial erosion in the softer rock 
•ehind the sheet of massive andesite at the northern end of the lake, 
iv-ver which the presenl drainage escapes to Arrastra Gulch. The 
larks ot* glacial scoring are still plainly visible on this resistant sill, 
hrough which the clear water escaping from the post-Glacial lake has 
een unable to cut. The original beauty of this little sheet of water 
" as been marred by mining operations, particularly by a partial fi.ll- 
; ig with tailings from the Silver Lake mill. The basin is well above 
1 imber line, and the mine buildings are sometimes seriously damaged 
1 y snow slides. Mine timbers are packed in from Deer Park by 
1 urros, over the col or saddle at the southern end of the basin. 
[ 'he main communication with the mines, however, is by the trail and 
1 tie wire-rope tramways running' up Arrastra Gulch. 
The rocks in which the basin has been carved, and which form the 
Formerly known as Arrastra Lake, and still so designated on the maps of the General Land 
< Sice. This is also the name of the post-office at the Silver Lake mine. 
Bull. 182—01 10 145 
