U. S. GEOLOGICAL SURVEY 
BULLETIN NO 
SHEETEI 
ICTURE IN CLIFFS OF SAN JUAN BRECCIA ABOVE THE SILVER LINK 
MINE, CANYON OF THE UNCOMPAHGRE RIVER 
The breccia rests upon the eroded surface of Algonkian schists and quartzites. Photograph by Whitman 
Cross. 
