260 CHEYENNE PASS. 



crossing the hills and hollows formed by the drains coming from 

 them, the undulations, however, being quite gentle. On our right, 

 about two miles distant, stretched a high table ridge, or plateau, 

 rising one hundred and fifty or two hundred feet, its western escarp- 

 ments abrupt, nearly vertical, and capped in this vicinity by argil- 

 laceous limestone and sandstones, with occasional strata of pud- 

 ding-stone. Between this plateau on our right and the Black 

 Hills on our left, there is a marked depression or valley, averaging 

 about four miles in width, and which appears to have been cut out 

 by the violent action of an immense body of water flowing in a 

 northern direction. The valley extends along the base of the 

 Black Hills, from where we first descended their eastern slope, to 

 the Chugwater ; the range of marly hills reaching, as our guides 

 told us, to the Platte, in the vicinity of Scott's Bluffs, and thence to 

 ^'Chimney Rock" and "The Court-house." The formation ap- 

 peared to be the same as that observed at those localities. The 

 depression thus formed is called the " Cheyenne Pass," from the 

 constant use made of it by that tribe in their migrations to and from 

 the Platte. From the red canon of Crow Creek to some distance 

 down the Chugwater, a range of lower hills, apparently of lime and 

 sandstone of different colours and qualities, occurs, flanking and 

 following the general direction of the main back-bone of the Black 

 Hills. Through these, the numerous streams which take their 

 rise in the ridge beyond have forced a passage in deep, narrow, 

 and rugged canons, and, after crossing the Cheyenne Pass, have 

 broken through the marly plateau on our right, in their passage 

 through the plains to the eastward into the North and South Forks 

 of the Platte. 



Following the Cheyenne Pass nine miles from our morning's 

 camp, after crossing the north or main fork of Crow Creek, some 

 two miles below its canon, we struck upon the southern branch of 

 Lodge-pole Creek, and, five miles beyond, halted to noon upon 

 Bear Creek, one of its tributaries, where a meridian observation 

 gave for the latitude 41° 2V 45''.7. 



We had now reached the heads of the stream, which I had pre- 

 viously determined to follow to its confluence with the South Fork 

 of the Platte. As we could expect to receive no addition to our 

 supplies before reaching Fort Kearny, I despatched an express to 

 Fort Laramie for such articles of food as were required, and occu- 

 pied the interval until their return in making an examination of 

 the eastern base of the Black Hills to the northward. 



