.0 LOCATION MAP OF MAJOR TECTONIC AND GEOGRAPHIC FEATURES 6. Leadville quadrangle Tweto, Ogden, Moench, R.H., and Reed, J.C., Jr., 1978, Geologic map of the Leadville 1 X 2 quadrangle, northwestern Colorado: U.S. Geol. Survey Misc. Inv. Series Map I-999. 7. Denver quadrangle Bryant, Bruce, U.S. Geol. Survey unpub. compilation of northwest part of quadrangle. Bryant, Bruce, and Wobus, R.A., 1975, Preliminary geologic map of the southwestern quarter of the Denver 1 X 2 quadrangle, Colorado: U.S. Geol. Survey Open-file Rept. 75-340. McGrew, L.W., U.S. Geol. Survey unpub. map of eastern part of quadrangle. Soister, P.E., U.S. Geol. Survey unpub. map of Denver and Dawson Formations. Trimble, D.E., U.S. Geol. Survey unpub. maps of Front Range Urban Corridor, Greater Denver and Colorado Springs-Castle Rock areas. 8. Limon quadrangle Sharps, J.A., U.S. Geol. Survey unpub. map of quadrangle. 9. Moab quadrangle Williams, P.L., 1964, Geology, structure, and uranium deposits of the Moab quadrangle, Colorado and Utah: U.S. Geol. Survey Misc. Geol. Inv. Map I-360. Supplementary data on Precambrian rocks from: Case, J.E., 1966, Geophysical anomalies over Precambrian rocks, northwestern Uncompahgre Plateau, Utah and Colorado: Am. Assoc. Petroleum Geologists Bull., v. 50, no. 7, p. 1423-1443. Hedge, C.E., Peterman, Z.E., Case, J.E., and Obradovich, J.D., 1968, Precambrian geochronology of the northwestern Uncompahgre Plateau, Utah and Colorado, in Geological Survey Research 1968: U.S. Geol. Survey Prof. Paper 600-C, p. C91-C96. Mose, D.G., and Bickford, M.E., 1969, Precambrian geochronology in the Unaweep Canyon, west-central Colorado: Jour. Geophysical Research, v. 74, no. 6, p. 1677-1687. 10. Montrose quadrangle Tweto, Ogden, Steven, T.A., Hail, W.J., Jr., and Moench, R.H., 1976, Preliminary geologic map of the Montrose 1 X 2 quadrangle, southwestern Colorado: U.S. Geol. Survey Misc. Field Studies Map MF-761. 11. Pueblo quadrangle Scott, G.R., Taylor, R.B., Epis, R.C., and Wobus, R.A., 1978, Geologic map of the Pueblo 1 X 2 quadrangle, south-central Colorado: U.S. Geol. Survey Misc. Inv. Series Map I-1022. 12. Lamar quadrangle Sharps, J.A., 1976, Geologic map of the Lamar quadrangle, Colorado and Kansas: U.S. Geol. Survey Misc. Inv. Series Map I-944. Supplementary data on bedrock from: Boettcher, A.J., 1964, Geology and ground-water resources in eastern Cheyenne and Kiowa Counties, Colorado, with a section on Chemical quality of the ground water, by C.A. Horr: U.S. Geol. Survey Water- Supply Paper 1779-N, 32 p. Coffin, D.L., 1967, Geology and ground-water resources of the Big Sandy Creek valley, Lincoln, Cheyenne, and Kiowa Counties, Colorado, with a section on Chemical quality of ground water, by C.A. Horr: U.S. Geol. Survey Water-Supply Paper 1843, 49 p. Voegeli, P.T., Sr., and Hershey, L.A., 1965, Geology and ground-water resources of Prowers County, Colorado: U.S. Geol. Survey Water-Supply Paper 1772, 101 p. Weist, W.G., Jr., 1965, Geology and occurrence of ground water in Otero County and the southern part of Crowley County, Colorado, with sections on Hydrology of the Arkansas River valley in the project area, by W.G. Weist, Jr., and E.D. Jenkins; Hydraulic properties of the water-bearing materials, by E.D. Jenkins; and Quality of the ground water, by C.A. Horr: U.S. Geol. Survey Water-Supply Paper 1799, 90 p. 13. Cortez quadrangle Haynes, D.D., Vogel, J.D., and Wyant, D.G., 1972, Geology, structure, and uranium deposits of the Cortez quadrangle, Colorado and Utah: U.S. Geol. Survey Misc. Geol. Inv. Map I-629. 14. Durango quadrangle Steven, T.A., Lipman, P.W., Hail, W.J., Jr., Barker, Fred, and Luedke, R.G., 1974, Geologic map of the Durango quadrangle, southwestern Colorado: U.S. Geol. Survey Misc. Inv. Series Map I-764. Supplementary data on surficial deposits from: Atwood, W.W., and Mather, K.F., 1932, Physiography and Quaternary geology of the San Juan Mountains, Colorado: U.S. Geol. Survey Prof. Paper 166, 176 p. Richmond, G.M., 1965, Quaternary stratigraphy of the Durango area, San Juan Mountains, Colorado, in Geological Survey Research 1965: U.S. Geol. Survey Prof. Paper 525-C, p. C137-C143. 15. Trinidad quadrangle Johnson, R.B., 1969, Geologic map of the Trinidad quadrangle, south- central Colorado: U.S. Geol. Survey Misc. Geol. Inv. Map I-558. Supplementary data from: Boyer, R.E., 1962, Petrology and structure of the southern Wet Mountains, Colorado: Geol. Soc. America Bull., v. 73, no. 9, p. 1047-1070. Burroughs, R.L., 1971, Geology of the San Luis Hills, south-central Colorado, in New Mexico Geol. Soc. Guidebook 22d Field Conf., San Luis Basin, Colorado, 1971: p. 277-287. Also, unpub. geologic map of San Luis Hills area. Cochran, D.M., 1974, Charles S. Robinson and Associates, Inc., unpub. geologic map of Forbes Trinchera Ranch. Gaca, J.R., and Karig, D.E., 1966, Gravity survey in the San Luis Valley area, Colorado: U.S. Geol. Survey open-file report, 22 p. Kleinkopf, M.D., Peterson, D.L., and Johnson, R.B., 1970, Reconnaissance geophysical studies of the Trinidad quadrangle, south-central Colorado, in Geological Survey Research 1970: U.S. Geol. Survey Prof. Paper 700-B, p. B78-B85. McCulloch, D.S., 1963, Late Cenozoic history of Huerfano Park, Colorado: Michigan Univ. Ph.D. thesis, 158 p. Scott, G.R., and Taylor, R.B., 1975, Post-Paleocene Tertiary rocks and Quaternary volcanic ash of the Wet Mountain Valley, Colorado: U.S. Geol. Survey Prof. Paper 868, 15 p. Tweto, Ogden, U.S. Geol. Survey reconnaissance mapping. Vine, J.D., 1974, Geologic map and cross sections of the LaVeta Pass, LaVeta, and Ritter Arroyo quadrangles, Huerfano and Costilla Counties, Colorado: U.S. Geol. Survey Misc. Inv. Series Map I-833. 16. LaJunta quadrangle Scott, G.R., 1968, Geologic and structure contour map of the LaJunta quadrangle, Colorado and Kansas: U.S. Geol. Survey Misc. Geol. Inv. Map I-560.