Laserfiche WebLink
<br />r. ... ~ 1- rl ( <br />uu... tJ. <br /> <br />21. <br /> <br />water. In some places, the deep penetration may be in vain because <br />the underlying water is salty. <br /> <br />., <br /> <br />" <br /> <br />The consolidated formations younger than the Mancos contain <br />water generally adequate only for domestic and stock supplies, al- <br />though in some areas where these younger rocks are thick, supplies <br />large enough to furnish small towns might be obtained. More information <br />is needed however, before the water-yielding properties of the younger <br />rocks, especially those of Tertiary age, can be properly appraised <br />even in general terms. <br /> <br />For an understanding of the areal extent of the various water- <br />bearing formations in western Colorado, the reader is referred to the <br />geologic map of Colorado."!J Certain general statements, however, may <br />be useful to those who do not have ready reference to the geologic map. <br /> <br />. <br /> <br />In the western one-fourth of the State, rocks older than the <br />Mancos predominate at or near the surface south of the Grand Valley; <br />whereas, rocks younger than the Mancos predominate at or near the <br />surface north of the Grand Valley. <br /> <br />Between the western one-fourth of the State and the Front Range <br />of the Rocky Mountains the complex geologic structure has exposed <br />rocks of all ages, the occurrence of anyone formation or group of forma- <br />tions within a particular age group being relatively small in areal extent. <br />Again using the Mancos as a reference plane, most of this area has <br />surface rocks older than the Mancos or is covered with igneous rocks of <br />Tertiary age underlain by rocks much older than the Mancos. None <br />of these are known to be good aquifers except locally. Scattered <br />throughout the area, however, are small areas underlain by water- <br />bearing beds belonging to the geologic units ranging from Triassic to <br />Tertiary age. The water-bearing properties of these units probably <br />are similar to those of corresponding units in the area to the west. <br /> <br />Ground water is known to occur in some of the dense rocks of <br />sedimentary, metamorphic, or igneous origin where fracturing, faulting, <br />weathering and water have created extensive cracks, crevices and <br />solution channels that lie below the water table. Very detailed studies <br /> <br />.' <br /> <br />1/ Burbank, W. S., Lovering, T. S., Goddard, E. N., and Eckel, <br />E. B., 1935, Geologic map of Colorado: U. S. Geological Sur- <br />vey. <br /> <br />" <br /> <br />- 5 - <br />