In the southeastern counties of Idaho there lies an extensive shore-line of middle carboniferous limestones and shales, which has been outlined by the United States Geological Survey, and a very large portion of which is contained in Bannock county. This in its entirety composes the largest phosphate field in the world, the rock phosphate of the deposit being seventy per cent pure, in beds of from three to eight feet thick. In December, 1908, the secretary of the interior withdrew from all kinds of entry 4,541,300 acres of land, part of which extends over the Utah line, pending an examination of their phosphate resources. During the summer of 1909, the United States Geological Survey conducted field work on this area, which resulted in the restoration of some of these lands and the withdrawal of others. The total area now withheld is 2,551,399 acres. The rock phosphate deposits of Bannock county are original sedimentary formations made when this part of the earth was still under water. Since then other rock-forming sediments have accumulated, so that thousands of feet of subsequent strata have overlain them. Deformation of the earth’s surface has broken these strata, which originally lay flat. Hence these rock-phosphate deposits resemble coal and limestone, rather than ore deposits, such as veins or lodes. No entirely satisfactory explanation of their source or manner of accumulation has yet been given. The value of these deposits will be more readily understood when it is known that prior to their discovery the total known supply in the United States was barely sufficient to last forty years. In addition to this, most of the deposits were in the control of European investors, which threatened to put the American farmer at the mercy of foreign speculators. In his book entitled, “The Conservation of Natural Resources of the United States,” Professor Van Hise, of the University of Wisconsin, says: “The most fundamental of the resources of this nation is the soil, which produces our food and clothing, and one of the most precious of the natural resources of America, having a value inestimably greater than might be supposed from the present market value, is our phosphate-rock resources.” Phosphoric acid is essentially a soil fertilizer. It is really nothing else than a rich manure, as the odoriferous smell given off when two pieces are rubbed together amply testifies. The enormous deposits of this powerful fertilizer practically insure the agricultural future of Idaho. The secretary of the interior, in a recent report, said: “The present crop yields of the virgin fields of the west under irrigation cannot be expected to be maintained by irrigation water alone, and the intensive methods of that region will within a few years have to figure on artificial fertilizers to maintain their great yield.” And Nature, foreseeing our future need, has provided for it in advance.