6 



Loam is not an important type in the North Platte Valley, and 

 occurs only near the Brule clay buttes or Brule clay outcrops, and 

 here and there along the Platte bottoms. Frequently it is underlaid 

 near its surface with un weathered Brule clay. Trees will not thrive 

 in such situations, since their roots can not penetrate the subsoil. In 

 the South Platte region the loam type covers a considerable part of the 

 upland area where it forms a very heavy soil, which, when dry, clods 

 readily and becomes exceedingly hard. It is underlaid at a depth of 

 from 3 to 6 feet by a subsoil which varies from sand to sandy loam 

 or even cla}^, and which absorbs water readily and retains it for long 

 periods. Such land is especially adapted to orchard crops. Both the 

 loam and sandy loam soils are very rich, and under irrigation are 

 adapted to the growth of a number of tree species. 



Sand exists chiefly in the sand-hill formation of the North Platte 

 Valley in eastern Wyoming, on the north side of the river, and along 

 portions of the Interstate Canal, especially between Wyncote and 

 Laramie. Though not so common in the South Platte Valley, small 

 patches are found throughout most of the region. The subsoil is not 

 essentially different in composition from the surface soil. If set with 

 grasses or shrubby growth sufficiently dense to protect the surface 

 from wind erosion, these sandy lands are adapted to the growth of 

 certain trees, such as pines. Bare, shifting sands can not be planted. 



In the North Platte Valley the gravelly loam type occurs in scat- 

 tered areas on a few of the higher hills and ridges, which can not be 

 irrigated. In the South Platte region the gravelly loams, when they 

 occur within the irrigated systems, are found near the Rocky Moun- 

 tain foothills. This class of land is usually hard to irrigate. Where 

 it can be given sufficient water, it is well adapted to the growth of 

 fruits and certain field crops, such as small grain, alfalfa, and sugar 

 beets. Forest planting is feasible where these crops can be grown. 



CLIMATE. 



The climate is characteristic of the semiarid plains. Some of the 

 more striking features are illustrated by the following table, com- 

 piled from records of the United States Weather Bureau: 



Temperature and precipitation in the North Platte and South Platte valleys. 



Leroy, Colo., lies a few miles to the east of the South Platte Valley, but weather conditions there 

 are practically the same as for the valley in that part of the State. 

 bAlso July 8, 1901, and July 15, 1902. 



[Cir. 109] 



