SYNOPSIS OF PART I. 
9 
was correspondingly rich in water. The question of the derivation of the vein 
minerals is discussed; derivation by leaching from the granitic or the volcanic 
rocks by cold or hot atmospheric waters is shown to be improbable. The view 
that most of the water and most of the substances contained in the veins were 
given off by intrusive bodies slowly cooling at considerable depth and were forced 
up through the upper part of the volcanic mountain as soon as the formation of 
fissures allowed them to rise is considered more plausible. The waters ascended 
in the deeper part of the volcano with comparatively great velocity on the fewer 
fissures here available. Nearing the surface they spread through a larger space in 
a more complicated fissure system. The speed became checked and conditions for 
precipitation improved. Deposition and the chemical action of the country rock 
changed the composition of the solutions and a mingling with fresh ascending 
waters, possibly also with atmospheric waters, induced further precipitation. In 
this manner are explained the smaller amount of ore deposited in depth and the 
richness and abundance of ore nearer to the old surface. The portion of the volcano 
removed by erosion may have contained still richer deposits. 
Future of the district .—It is probable that the production of the district, while 
exhibiting fluctuations, will on the whole slowlv decline. New ore bodies will 
undoubtedly be discovered from time to time, and individual mines may be as 
profitable in the future as they have been in the past, or even more so. An increased 
output may be expected to follow each successful step in deep drainage. But 
existing conditions indicate that if the maximum production of $18,000,000 in 1900 
is to be surpassed the increase will be due to the ore bodies encountered in a zone 
within 1,000 feet of the present general surface. 
CHAPTER XII.-UNDERGROUND WATER. 
Although the annual precipitation at Cripple Creek is not heavy and the condi¬ 
tions for rapid run-off are unusually favorable, standing water was originally 
encountered in the mines at moderate depths. At the beginning of mining opera¬ 
tions the underground water surface stood at an elevation of about 9,500 feet in the 
western part of the district and, on an average, fully 100 feet higher in the eastern 
part. Several mines began pumping about the year 1895, but it was soon found 
that this mode of lowering the water was slow and costly. Attention was directed 
to tunneling, and the Ophelia tunnel was driven into Gold Hill at an elevation of 
9,268 feet. This tunnel drained the western part of the district until 1898, when 
the Standard tunnel, over 200 feet lower, tapped the phonolite of Beacon Hill and 
became the chief effluent. Finally the El Paso tunnel, with its portal at an eleva¬ 
tion of 8,783 feet, was driven under Beacon Hill in 1903 and has since been the main 
drainage outlet of the district. Prior to January 1, 1905, this tunnel is estimated 
to have discharged about 3,550,000,000 gallons or nearly 15,000,000 tons of water. 
The records of the pumping operations and tunnel projects show that the under¬ 
ground water is for the most part held within open fissures and cavities in the rocks 
of the volcanic neck. It is stored water, inclosed by the relatively impervious rim 
of granitic and schistose rocks that form the general Cripple Creek plateau, and has 
been supplied by the rain and snow that fell upon the surface of the district. 
