Show northern utah phosphate deposits by WILLIAM since 1908 extensive work has been done both by private individuals and the V U S geological survey to determine the amount and character of the rock phosphate in the rocky mountain region the principal work of the investigation of the deposits however has been confined to the well known horizon in the rocks of upper pennsylvania of permian age it is now known that phosphate exists in the mississippian lan rocks in a zone more than 2000 feet below the phosphate horizon that has heretofore been given so much study the zone containing the phosphate is ore lore than feet thick and consists 0 oi layers of phosphate and black and brown shale hale with inter stratified layers of sandy lionstone bestone liln me stone in extent it is known to out crop op in a north south direction for more than forty arty miles and sections studied show 4 1 1 department of geology utah al college logan utah litah in science it to have an area of more than one hundred square miles it has been reported as far south as ogden canyon canyons but no detailed section has been measured in that locality on the east side of cache valley the phosphate rocks have been prospected for coal and this exposure has given the best opportunity for detailed study the races of the mountains which form the eastern boundary of the valley is a weathered fault scarp which terminates the western limb ot a syncline the ledges on the face of the mountain are exceptionally well exposed the rock being principally bluish gray lime ime stones with thin beds of shale and quartzite here the geologic section is well exposed and shows silurian rocks at the base and pennsylvanian at the top of the succession only the lower members of the pennsylvanian syl or permian are present in this locality observations on the fac face e of the moun Blackwel hackwelder lack welder ae r U S geol survey bull bains which extend more than feet feel above the valley show that the rocks strike N 10 degrees to 14 degrees E and dip eastward from 20 degrees to 30 degrees the beds flatten to the eastward and about six miles east of the face they rise again the strata on the eastern limb of the syncline dipping as much as 10 degrees to the west erosion has clearly exposed the higher beds on the eastern limb of the syncline 2 the phosphate rock is exposed on both the east and west limbs of the syncline which lies near the top of the range the logan river has cut through the range from east to west and has made a good exposure of all the strata included in the upper part of the synclinal fold the phosphate zone therefore lies in two separate areas one to the north and one to the south of the river the mississippian rocks are well upon the western side of the mountains forming the eastern boundary of cache valley and even in the lowest part of the fold in the canyon they are more than 1000 feet above the river the zone containing the phosphate is exposed in a cliff of very compact bluish gray limestone which is usually more than a hundred feet thick and contains an abundance of cup corals corald at the base of this cliff there is a lean zone from five to seven feet thick of sha e containing a few bands of chert the shale also contains several thin layers of oolitic rock phosphate ranging from one half to one inch in thickness thic knes one sample taken from all of these layers yielded only per cent phosphate this zone is probably of no economic value it has been prospected in a number of places for coal the thicker and richer phosphate zone lies just above the thick ledge of limestone the phosphate rocks are less resistant to erosion than the underlying and overlying limestone ledges and the latter stand out more prominently than the included softer beds the rocks in the phosphate zone which are generally dark colored contain thin bands of limestone lime sione with shale and some chert measurements of some of the beds were taken in providence canyon and are shown in the table below 6 at the top of the phosphate zone tho jhb rocks are not sufficiently well exposed to aff afford ord detailed study A tunnel driven near the upper limestone ledge shows a few inches of good rock phosphate inter stratified with dark colored limestone and shale thirty feet below this ledge awen twenty ty inches of oolitic phosphate rock was measured and a sample no 3 1 yielded 55 per cent capoa CaPO 2 in the next thirty feet below there are thin bands of oolitic phosphate but none of them are believed to be thick enough to be of economic value the details of the lower part of the bed in providence canyon follow per cent no kind of work ca capois PO 3 feet dark gray limestone 2 18 inches shale 3 12 inches phosphate rock 1671 4 48 inches dark phosphate rock 24 inches gray limestone 5 48 inches shale some layers 14 6 11 inches black shale 7 30 inches shale oolitic phosphate in bands 2130 24 inches sandy limestone 9 38 inches phosphate rock IS 18 inches chert 12 inches black shale 10 30 inches phosphate rock 11 12 inches phosphate rock 2 inches cinches black chert see geological map parts of western wyoming southeastern idaho and northeastern utah hayden survey 1877 3 91 12 48 inches black shale 6 inches black chert inches black oolitic phosphate 21 1 13 6 rock I 1 inch black chert 14 12 inches black phosphate rock T 15 18 inches brown oolitic phosphate rock 2001 2831 20 01 bedding planes 6 inches shale 16 6 inches shale showing phosphate in 2 inches chert 17 4 inches phosphates rock 2712 20 inches sandy limestone 18 18 inches brown oolitic phosphate rock 12 inches black shale 16 inches black shale with bands of chert 5 inches brown oolitic phosphate rock 7 inches shale 2 inches oolitic phosphate rock with much hematite limestone ledge the samples for analysis were taken only two or three feet under ander the surface and it seems quite probable that they have been considerably leached beached for the rock is less firm and crumbles more easily than that from the upper Pennsyl pennsylvania vanla or permian horizon no sampling has been done below the level to which roots penetrate it is thought the amount of phosphate may decrease to some extent with depth owing to the leaching of the less soluble constituents and the concentration of the phosphoric acid in the leached beached zone one very noticeable feature in the phosphate zone in this locality which is an aid in tracing the phosphate is that usually the growth of vegetation is denser along the line of outcrop than elsewhere on hillsides hill sides which face the south and therefore have but little moisture or vegetation growths of wild cherry maple and aspen extend along the outcrop As a few small seeps and springs issue from the phosphate the denser vegetation there should perhaps be partly accounted account ea for by the moisture at a place four miles north of the locality in providence canyon where th the e samples mentioned were obtained two other samples were taken from separate layers of oolitic phosphate rock near the lomei part of the deposit the sample from one bed 18 inches thick yielded per c cent phosphate 3 the other sample from a tied bed 42 inches thick yielded 1 per cent of the material the section does not seem to agree in detail with the measure the athe analyses were mostly made by mr C T hirst in the D experiment S station tat I 1 on chemical laboratory ments r made nad e in providence canyon it n thought by the writer that the fj rocks are sufficiently rich in tri calciu 1111 phosphate to warrant investigation as to their economic value |