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<br />OO?l~o'5 <br /> <br />. <br /> <br />. <br /> <br /> <br />UNITED STATES <br />DEPARTMENT OF THE INTERIOR <br />GEOLOGICAL SURVEY <br /> <br />SUMMARY OF ACTIVITIES IN THE PACIFIC SOUTHWEST <br />JULY-DECEMB~R 1959 <br /> <br />Geolo~ic and mineral-resourse surveyS and mapping <br /> <br />About 150 projects were active in the Pacific Southwest region <br />during the report period. Most of these are concerned with mineral and <br />mineral-fuel resources or seek data fundamental to land development and <br />engineering construction. The following reports were published: <br /> <br />"Regional geophysical investigations of the Uravan area", by <br />H. R. Joesting, and P. E. Byerly, Professional Paper 3l6-A. <br />Areo-magnetic and gravity surveys have aided the intetpretation <br />of bedrock geologic features of the Colorado Plateau. The <br />larger magnetic variations are related to variations in rock <br />type, and to abrupt changes across faults. Large negative <br />gravity anomalies were associated with salt anticlines; other <br />gravity anomalies are attributed to faults and to structures <br />related .to migration of .evaporities. <br /> <br />"Core logs from Searles Lake, San Bernardino County", by <br />D. V. Haines, Bulletin 1045-E. Two main layers of salines <br />separated by mud, occur in an area of 39 square miles. The <br />major minerals are' halite, trona, handsite, borax, and <br />burkeite. <br /> <br />"Preliminary study of radioactive limonite in Colorado, Utah, <br />and Wyoming", by T. G. Lovering and E. P. Beroni, Bulletin <br />104b-N. Significant correlations of uranium and thorium with <br />various conunon elements are suggested in this study of samples <br />from 9 localities. Greater-than-normal concentrations of these <br />conunon elements in soil samples may be useful guides in pros- <br />pecting for uranium and thorium deposits in covered areas. <br /> <br />"Stratigraphy of Triassic and associated formations in part <br />of the Colorado Plateau region"-, by J. H. Stewart, G. A. <br />Williams, A. F. Albee, and R. B. Raup, with a section on <br />sedimentary petrology by R. A. Cadigan, Bulletin 1046-A. <br />Triassic strata in the Colorado Plateau comprise the Moenkopi, <br />Chinle, and Wingate formations. The Moenkopi formation con~ <br />tains fluvial and marine units that were reposited in tidal <br />flats. The Chinle formation is a continental deposit, and <br />contains many uranium deposits near its base. The Wingate <br />sandstone formed as eolian deposits. <br /> <br />-1- <br /> <br />" <br />