GEOLOGICAL SURVEY OF THE TERRITORIES. 229 



the river, leaving a narrow belt of bottom land. For some distance 

 above Fort Fetterman there is a broad valley, partly bottom land and 

 partly the second level, all of which could be easily irrigated, and would 

 afford a fine farming region. 



I think we may safely estimate the average width of the immediate 

 valley of the river, from Fort Casper, or the Old Bridge, to the territo- 

 rial line, at four miles. This alone would give a cultivable area of six 

 hundred square miles. Add to this the additional amount which can be 

 brought into use by the canals heretofore proposed, and the estimate I 

 have given for this section will not appear too large. 



West of Fort Fetterman, Deer and Box Elder Creeks flow into the 

 Platte from the south, each affording a narrow belt of irrigable land, 

 and fields of excellent pasturage, the principal supply of hay for the 

 fort being cut from the valley of Deer Creek. The La Prele, which con- 

 nects with the Platte near the fort, is bordered chiefly by high hills and 

 bluffs, its bottoms being narrow and irregular and the supply of water 

 small. 



There is one thing which will probably have a tendency to retard the 

 settlement of this part of the Platte Valley ; that is the wind. Our at- 

 tention was first called to this while crossing a broad valley a few miles 

 south of Fetterman, where a strong and constant wind swept down upon 

 us from the west. While camping on the La Prele this was of daily oc- 

 currence; and from Fetterman to Poison Spring Creek we felt its effects 

 each day, except when sheltered behind some bluff or ridge. While 

 crossing the river near .old Fort Casper, and for a few miles along the 

 north bank, where we were directly opposite the mouth of the gorge, 

 the wind was so strong that we were compelled to tie our hats upon our 

 heads, yet the day was clear and sunny. 



Fremont in his report says this place is celebrated for winds, of which 

 the prevailing ones are west ; which corresponds with our experience, 

 with this exception, that when south of Fetterman they came from the 

 northwest. Stansbury, while in the vicinity of Box Elder Creek, speaks 

 of a " brsk wind from the northwest," adding that the morning was 

 bright and cool. And he also states that after he had passed through 

 the gap to the vicinity of Poison Spring Creek, ik the wind rose from the 

 southwest and blew almost a hurricane the whole day, tearing up the 

 sand and gravel, and dashing it into our faces, as we rode, with such 

 violence as to cause sensible pain." And the cause of this I think is 

 apparent. Here the mountain range is completely severed, and an open 

 gap exists between the western and eastern plains. Through this the 

 cooler surface atmosphere of the higher mountain plains rushes down to 

 fill the space left by the warmer ascending air of the broad eastern 

 plains. It is true this kind of movement is going on along the entire 

 mountain range, but it is in a quiet manner, while here the entire vol- 

 ume from a broad expanse is pressed through a narrow channel, and as 

 a necessary consequence the current is strong. Having passed through 

 the gap it expands upon the open space to the east, sending currents 

 along the valleys north and south. 



Between Fort Fetterman and Laramie River a number of streams 

 rising in the Black Hills run east and empty into the Platte, the most 

 important of which are the La Bonte, Elkhorn, Horseshoe and Bitter 

 Cottonwood. The La Bonte drains a very pretty and fertile valley 

 which is of moderate width, and is covered at points with groves of 

 cottonwood, willow, &c. This valley is pretty well shielded, for most of 

 its length, by high hills which border it on each side, and presents a good 

 point tor a small farming settlement. Horseshoe and Elkhorn Creeks 



