GEOLOGICAL SURVEY OF THE TERRITORIES. 453 



streams water rests on the impervious bottoms at the depth of 10 to 15 

 feet ; and conduits, with a fall of 2 to 4 feet to the mile, will bring it out 

 to the points where needed- 

 Power for raising water from streams or wells will be furnished by 

 the winds, by cattle, or steam. If Ericsson succeeds with his solar en- 

 gine it may come into use in this country of much sunshine. But 

 the wind-mill, for irrigating purposes, particularly where water is to be 

 raised from wells, 'is likely to be the main reliance. 



The project of carrying the South Platte eastward from the canon, in 

 a grand canal along the divide, will no doubt be realized in a compara- 

 tively short time. Eeaching past the heads of the streams crossed by 

 the railway between Cedar Point and Denver, the canal, in fertilizing 

 its million acres, will add to the quantity of water directly flowing from 

 it as by its modifying influence on the climate. 



The suggestion of J. A. Hodder, esq., of Cincinnati, that streams 

 from the mountains might be led out to irrigate considerable districts, 

 and the surplus water be accumulated in lakes for use as the vicissitudes 

 of the seasons may require, will probably be found worthy of grave con- 

 sideration as the population and the ability to accomplish large works 

 increase. 



While it is held that, in addition to natural grasses, there may 

 be a large production of food for live stock, and of grains for bread, 

 without irrigation, in many if not all parts of the Plains, it is yet equally 

 certain that irrigation is essential for some kinds of vegetation in many 

 localities. What would be a great benefit in Pennsylvania or Ohio, if 

 applied, is absolutely necessary for full success with some particular 

 crops in that part of the campestrian province west of the one hun- 

 dredth meridian. Hence, in looking forward to the reduction of a vast 

 region to productive uses, problems of irrigation are to be considered, 

 and in due time they will be solved in the daily life of the future 

 inhabitants. 



CLIMATE. 



The Plains have been so often described as a " rainless region," that 

 great misconception in regard to the climate has prevailed. The abso- 

 lute precipitation is much greater than has been in past years supposed, 

 and is due to other causes. Meteorologists who have described the rain- 

 fall of the Plains as derived only or principally from the remaining mois- 

 ture of winds from the Pacific, after the passage of the Nevada and 

 Eocky Mountain ranges, have been greatly in error, and the better con- 

 clusion now is, with all authorities who have given any special attention 

 to the subject, that the moisture which fertilizes the Mississippi Valley, 

 including the broad, grassy plains, is derived from the Gulf of Mexico. 



Within a few years the rain gauge has been brought into service at 

 points distant from each other, but located at irregular intervals across 

 the continent, and its record shows not only greater precipitation than 

 was formerly believed to take place on the Plains, but that the distri- 

 bution is unequal in time, giving us the largest proportion in the grow- 

 ing seasons, spring and summer. 



In his late work, " The Mississippi Valley," Professor J. W. Foster 

 says : " The rains which water the Atlantic slope are equally distributed, 

 the variations between the four seasons being very slight," while " those 

 which water the Mississippi Valley are unequally distributed, those of 

 spring and summer being greatly in excess;" " a fact," he says, "which 

 has been overlooked by most meteorologists in reference to the geologi- 

 cal distribution of plants." As we pass westward from the Atlantic the 



