128 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



North of Fort Hall station, 1 to 3 miles east of the track, there is a 

 group of low rounded hills composed largely of basalt lava but covered 

 for the most part with dark sand that was blown out from a volcano, 

 the basalt appearing here and there as ledges and bowlders of black 

 rock. From Fort Hall station an excellent view may be obtained 

 of the highest mountains in the reservation, North and South Putnam, 

 situated 15 to 18 miles to the southeast and reaching 8,837 and 8,989 

 feet, respectively, above sea level. 



North and west of Fort Hall station the surface of the flat is over- 

 spread with dark sand, largely of volcanic origin. It is similar to 

 volcanic ash except that it is coarser. This sand is piled in low dunes 

 west of Fort Hall, and some of the dmies have been utilized as burial 

 places by the Indians. These Indian cemeteries are marked by 

 high poles, set rather close together, which may be seen for consid- 

 erable distances. A cemetery about 2 miles west of the track and 1 

 mile north of Fort Hall can be seen from the train in clear weather. 

 On close inspection the cemeteries are found to be decorated with 

 effects of the departed Indians, including clothing, cooking utensils, 

 and implements. 



gold prospects. 



analy 



a grayiph color. WTien freshly mined, 



grade however, the rock is dark bro^vn or black. 



phosphate rock. In 1908, on recommen- 

 dation of the Geological Sui'A'ey, Secre- 

 tary of the Interior Garfield withdrew 

 from entry 4,500,000 acres of pubUc land 

 in Idaho, Utah, and Wyoming believed 



to be valuable for phosphate, and this 

 phosphate withdrawal was continued by 

 President Taft under the act of June 25, 

 1910. In 1909 and succeeding years these 

 phosphate deposits were systematically 

 examined by the United States Geological 

 Survey, and in 1910 phosphate rock was 

 discovered in Montana, near Melrose, by 

 Geologist II. S. Gale. On January 1, 

 1915, the total area of phosphate lands in 

 Montana, Utah , Wyoming, and Idaho 

 withdrawn from entry was 2,713,155 acres. 

 This phosphate reserve is larger than any 

 similar area in the United States; it is, 

 indeed, the largest area of phosphate rock 

 yet recognized in the world. 



A characteristic of the phosphate rock 

 of this region is its oolitic texture, the 

 rounded grains, resembling fish ^gs, 

 ranging in size from the tiniest specks to 

 bodies half an inch or more in diameter. 

 In its weathered condition these grains 

 are more or less distinct and the rock has 



In some places where the rock has b 

 subjected to great compression during the 

 deformation of the inclosing strata it has 

 apparently lost the oolitic texture and 

 shows a slight increase in density. 



The phosphate deposits in the West oc- 

 cui- in definite beds that extend over wide 

 areas and that are related to the associated 

 rocks in the same way as coal beds. The 

 associated beds are predominantly shaly, 

 but include ako sandstones and lime- 

 stones, the whole ranging in thickness 



from a few feet to 175 feet. 



these 



phosphate shales there is commonly mas- 

 sive chert or cherty limestone, and below 

 them in the Utah, Wyoming, and Idaho 

 fields a light-colored siliceoua limestone. 

 The:<e three sets of beds in Utah and west- 

 em Wyoming are grouped together a« the 

 Park City formation, of Carboniferous age. 

 In Idaho the phosphate shales and over- 

 lying chert are called the Phoephoria 

 formation. The number of phosphate 

 beds distributed throup^h fho nhnsr^hate 



vanes 



There 



is, however, usually near the base, a bed 

 5 or 6 feet thick in the Idaho field and the 

 adjacent portions of Wyoming and Utah- 



