Areal variation of lithic character._-___-__-___ 64 Phosphoria formation.__________________________ 74 Lower chert member. _______________________ 74 Meade Peak phosphatic shale member.________ 74 Petrography-__________________________ 75 Areal variation of thickness-_____________ 82 Areal variation of lithic types-___________ 82 Vertical variation of lithic types-_________ 83 Correlation of beds within the Meade Peak phosphatic shale member-____-____-_-. 83 Stratigraphic relations__________________ 84 Rex chert member._________________________ 84 Lithic character._______________________ 84 Areal variation of thickness-__-_-_____--. 86 Areal and vertical variation of lithic character. _________________________________ 86 Stratigraphic relations.__.-__-____-_____-86 Retort phosphatic shale member.__-_____-_.__ 86 Lithic character._______________________ 87 Areal variation of thickness-_____________ Page TABLE 1. Location, name, lot number, and source of stratigraphic sections used in this report_______________________ 2. Lithologic constitution in percent and total thickness of rocks of the geosyncline and craton in western Wyoming and adjacent areas-__ _ _ _ _ _ _.________________ _ _ ________________________________________________ 3. Optical properties of several apatites from the Permian rooks of western Wyoming._____._________________ 4. Size parameters of phosphorites ____________________________________________________________________ ,",. Analysis of variance of Po()5 values of four sets of spheroidal phosphorites subdivided by maximum spheroid size__________ ________________________________________________________________________________ 6. Distribution of minor minerals in rock cycle. ____________________________________________________ 7-11. Thickness and grade of phosphatic and uraniferous beds: 7. Used in calculations of phosphate reserves and uranium resources in the Gros Ventre Range, Wyo_____ 8. Of the Retort phosphatic shale tongue used in calculations of phosphate reserves and uranium resources in the Wind River Range, Wyo__-________--_________-__----_-__---_-___----______-___________ 9. Of the Meade Peak phosphatic shale tongue used in calculations of phosphate reserves and uranium resources in the Wind River Range, Wyo._____________________________________________________ 10. Used in calculations of phosphate reserves and uranium resources in the Big Hole, Teton, Snake River, and Caribou Ranges, Wyoming and Idaho___________________________________________________ 11. Used in calculations of phosphate reserves and uranium resources in the Hoback and Wyoming Ranges, Wyo________________ ______________________________________________________________ 12-19. Phosphate reserves:

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The rocks of the Phosphoria formation in northwestern Wyoming fall into five stratigraphic units, which, from oldest to youngest, are provisionally called the A, B, C, D, and E units. Units A, C, and E are composed dominantly of chert, tarbonate rock, and sandstone, whereas units B and D are composed dominantly of mudstone, phosphorite, and dark carbonate rock. Units C and D are continuous over all of northwestern Wyoming, whereas unit A grades into unit B and unit E grades into unit D to the southwest. Both units A and B pinch out to the north. With the possible exception of unit A, these units can be recognized in southwestern Montana. Units 3, C, and D are equivalent to the phosphatic.shale, Rex, and upper shale members of the Phosphoria formation in southeastern Idaho. The formation as a whole exhibits a facies change from dominantly chert, mudstone, and phosphorite in the southwestern part of northwestern Wyoming to dominantly carbonate rock and sandstone to the northeastern part. The facies change by thinning and pinching out of units and the in.ergradation of units. The rocks of the formation in the area of the report are cyclically deposited. The rock record of a single ideal cycle consists of, from base to top, carbonate rock, chert, phosphorite, chert, and carbonate rock. Sandstone and glauconite in general are found in the carbonate phases of the cycle whereas mudstone, pyrite, and organic matter are found in the chert and phosphorite phases of the cycle. An eastward transition from phosphorite to chest and chert to carbonate rock is analagous to the upper half of the cycle, i. e., phosphorite, chert, and carbonate rock in ascending order. The phosphorite phase of the cycle is represented by units B and D, whereas the other phases are represented by units A, C, and E. Two complete cycles are found in southwestern Wyoming. These stratigraphic relations represent two transgressions and regressions of areally zoned environments, The phosphorite phase is the most transgressive whereas the carbonate rock phase is the most regressive. The physical chemical environments in which the sediments accumulated probably varied between an environment with a pH of above 7.8 and an Eh of greater than zero for the carbonate rock phase of the cycle and an environment with a pH of less than 7.8 and an Eh of less than about-0.25 for the phosphorite phase of the cycle. These environments probably were effected by cold water upwelling on a shelf to the east. The transgressive and regressive migrations of the shelf probably were tectonically controlled.