ASPEN DISTRICT MAP. 145 
than the Castle Creek fault, and were faulted by it. They are very impor- 
tant in studying the economic geology of the district, smce the ore has 
been to a large extent deposited along them. 
Tourtelotte Park uplitt— Immediately after the formation of the Castle Creek 
fault, or perhaps synchronously with it, there began an uplift such as 
would arise from a vertically exerted force. This was a doming-up of the 
rocks just east of the Castle Creek fault, extending north and south over 
a limited area. The movement did not affect the rocks to the west of the 
fault, and thus the throw is correspondingly increased in the region of 
uplift. The summit of the dome is in the northern part of Tourtelotte 
Park, while the abrupt north side is on Aspen Mountain and ends very 
suddenly in the Roaring Fork Valley; the south 
side of the dome is gentler, and its structure 
is obscured by erosion, which has brought the 
granite to the surface. his uplift affected the 
granites as well as the sedimentary formations, 
but in the granite there is no means of meas- 
uring it, or even of ascertaining its existence. 
There are indications of a similar tendency 
toward local uplifting or doming at Lenado. 
Faulting —With the beginning of the forma- 
tion of this local dome there also began a 
system of local faulting, which continued 
from that time to the present. The first-formed 
system was parallel with the Castle Creek fault, and ihe faults belonging 
to it have a heavy throw, which is most pronounced on Aspen Mountain 
and diminishes from this pomt more or less rapidly to the north and to the 
south. At the same time there were formed many fractures without impor- 
tant throw, some of them being north-south and parallel with the actual 
Fia. 5.—Fractures in Weber limestone. 
faults, while others ran across in an east-west direction. In this way the 
summit of the dome, and, to a less extent, its sides, were profoundly frac- 
tured. Some graphic idea of this fracturing may be gained from the 
accompanying figure (fig. 5), which is from a photograph (natural size) 
of a small piece of thin-bedded Weber limestone. This specimen came 
from Tourtelotte Park, where faulting on a large scale is most pronounced, 
and it represents so closely in miniature the complicated fracturing which 
MON XXXI——10 
