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GUIDEBOOK OF THE WESTERN UNITED STATES. 



hill surmounted by a thick, square block of rock. This mesa was first 

 mentioned in tlie report of tlie exploration of Maj. Long, in 1820, and 

 on account of its resemblance to an old ruin was called Castle Rock. 

 As the train approaches milepost 32 the traveler may see that the 

 railroad is built around the foot of Castle Rock mesa, which is about 

 300 feet high and has a cap rock 60 or TO feet thick. 

 This mesa is shown in Plate XI, A, and in figure 7. 

 The lower part of the mesa is composed of soft, fri- 

 able beds of the Dawson arkose, but the cap rock is 

 a coarse conglomerate of pebbles and boulders of 

 crystalline rocks of all sorts that have been washed out from the 

 mountains and of a volcanic rock (rhyolite) which caps also some of 

 the adjacent mesas. These materials were washed out of the moun- 

 tains by streams of water and dropped as sheets of gravel and boul- 

 ders upon the surface of the land. The county seat of Douglas 



Castle Rock. 



Elevation 6,218 feet. 

 Population 461. 

 Denver 33 miles. 



Figure 7. — Castle Rock from tiie north. 



County, named in honor of Stephen A. Douglas, stands at the base 

 of the mesa and bears the name Castle Rock. It was formerly noted 

 for its stone quarries, the remains of which still disfigure the mesas, 

 but the increasing use of cement in construction work has so de- 

 pressed the market for ordinary building stone that the quarrying 

 industry has nearly disappeared. Samples of the stone may be seen 

 in the Douglas County High School building, on the right as the 

 train enters the town, and in the station building of the Denver & 

 Rio Grande Western Railroad." This stone was once molten lava 



"According to Richardson the rhyo- 

 lite is said to have been first quarried 

 about 1876, and it is reported that up 

 to 1914 about 30,000 carloads liad been 

 marlieted. The stone has been exten- 

 sively used for building in Denver, Colo- 

 rado Springs, and Pueblo, where it has 

 given general satisfaction. The quar- 

 ries, to which railroad spurs have been 

 constructed, are near the town of 



Castle Rock. The stone is readily 

 accessible, is easily worked, is of pleas- 

 ing gray to pinkish color, stands the 

 weather well, and is sufficiently strong 

 for ordinary purposes, although the 

 more porous varieties are not adapted 

 for use where great strength is desired. 

 In recent years the production of this 

 stone has fallen off because of the com- 

 petition of other building materials. 



