MOUNT ZION. 187 



In every other case where the junction of the Paleozoic outcrops with 

 the Archean has been observed, practically the same bed of quartzite has 

 been .found at the contact. In this case, however, on the saddle east of 

 this little hill, the White Limestone is found to abut against the granite, 

 while the Lower Quartzite sweeps around its northwest and southwest 

 slopes, showing that this point projected as a submerged island above the 

 level of the Cambrian beds at the time of their deposition. In the bed of 

 the stream opposite this saddle the Lower Quartzite beds are exposed in a 

 little canon gorge, with a strike of N. 30 E., and dipping 20 to the 

 southeast under the Lake beds which cover the spurs up to the steeper 

 slope of the hills near Leadville. 



The valley above has alluvial meadows, with flood-plain benches on 

 either side. In these benches on the northwest side is the Dugan quarry, 

 whence limestone was formerly taken as a flux for the Leadville smelters. 

 Higher up the valley, where the beds bend up over the arch of Archean, a 

 careful measurement was made of the cliff-exposures at two points, which, 

 in descending order, are as follows : 



1. Cliffs back of toll-gate. 



Feet. 



Wliite Porphyry . . - ? 



Quartzite and shale 25 



Lower Carboniferous . ^ Blue Limestone, with chert at top and bottom and 



with breccia at the base 125 



150 



Sandstone, eroded, with limestone breccia in eroded 



hollows 15 



Space covered 15 



Bluish limestone 8 



Silurian ( Wliite Limestone, bluish at base C6 



Sandy limestone 28 



White calcareous quartzite 22 



Reddish sandy limestones 27 



Limestone, gray at top, white at bottom 40 



221 



De"bris slopes to valley bottom. 



