Explorations and Surveys for the Pacific Railroad. 91 



to be highly productive. On this latter soil, water is found at a 

 depth of 30 feet. 



The steepest natural slope, in ascending to the summit of this 

 valley pass, (elevation 2,808 feet,) is 132 feet per mile for two 

 miles. * * * *. . * _ 



From the report of Capt. Pope, it would appear that the belt 

 of fertile land which lies on the west side of the Mississippi 

 throughout its length, extends on this route nearly to the head- 

 waters of the Colorado of Texas, in about longitude 102° — that 

 is, about three degrees farther west than on the more northern 

 routes. The evidence adduced in support of this opinion is, 

 however, not conclusive ; and, until it is rendered more complete, 

 the fertile soil must be considered in this, as in other latitudes, 

 to terminate about the 99th meridian. Thence to the Pacific 

 slopes the route is over uncultivable soil, though generally 

 grassed, the exceptions being, as on the route of the 35th par- 

 allel, in portions of the valleys of the Pecos, Eio Grande, Gila, 

 and Colorado of the West. The table-lands and mountain slopes 

 are usually well covered with grama-grass, and in New Mexico 

 have supported immense herds of cattle. There are exceptions 

 to this, however, on the greater portion of the Llano Estacado, 

 on portions of the plains between the Eio Grande and the Gila ; 

 and (comprised in that space) from Tuczon to the Gila, 80 miles, 

 there is no grass on the route travelled, nor is it to be found on 

 the Lower Gila valley ; occasional patches of bunch-grass only 

 being found on the plain, and a species of grama-grass some- 

 times upon the mountain sides. ISTo grass is found on the Colo- 

 rado desert, 135 miles along the line of location. 



The length of the route through this generally uncultivable 

 soil is 1,210 miles. Upon descending from the summit of the 

 San Gorgonio Pass, on the route to San Pedro, the soil is fertile, 

 and either well watered or can be irrigated. 



The principal characteristic of this route is the great extent of 

 high, arid, smooth, and nearly horizontal table-lands which it 

 traverses, reaching an elevation of 4,000 feet upon the dividing 

 ridge between the Brazos and Colorado rivers of Texas, near' 

 which elevation it continues until it descends from the pass of 

 the Sierra de Santa Catarina to the Gila river, a space of nearly 

 600 miles. The elevation at the summit of the Llano Estacado 

 is 4,700 feet, and in the passes of the Guadalupe and Hueco 

 mountains, east of the Eio Grande, 5,700 and 4,800 feet, respec- 

 tively. Between the Eio Grande and the Gila, the greatest ele- 

 vation, which is twice attained, is 5,200 feet ; the mean elevation, 

 before the descent to the Gila is commenced, being 4,100 feet. 

 From the eastern edge of the Llano Estacado to the pass of San 

 Gorgonio, 1,052 miles, the route crosses three rivers, the Pecos, 

 the Eio Grande, and the Great Colorado of the West. The pe-- 



