FOEMEE GLACIEES OF THE EOCKY MOUNTAINS. 71 



described as coming down into the valley in the vicinity of Jackson's Lake, 

 and this large body of water itself seems to have been formed, if not by 

 the actual damming back of the river by glacial agencies, at least by debris 

 washed down from a series of terminal moraines, now distinctly visible on 

 the western side of the valle}', the summit of the higlier and outermost 

 being at an altitude of 3G6 feet above the lake. Jenny's Lake, a little 

 fixrther south, which lies in the mouth of the Great Canon of the Teton 

 Range, where is gathered the entire drainage of the western side of the 

 group of the Three Tetons, is also described as a moraine lake, and at other 

 caiions in the range similar bodies of water occur. It is i-emarked by 

 Mr. Bradley, that in spite of the great size and prominence of the terminal 

 moraines, few remains of lateral ones could be discovered. This fiict 

 coincides witli wluit was observed by the writer and party at the head of 

 the South Platte. Another interesting point is, as Mr. Bradley remarks, 

 that " the water in these mountain streams is now so pure as to make it 

 certain that not tlie least glacial erosion is now going on at any point on 

 the ransre." 



In the preliminary report of the field-work of Dr. Hayden's parties for the 

 season of 1878, the latest published document of that Survey which has come 

 under the writer's notice, it is stated that morainal deposits and glaciated 

 rocks ai'e shown in the Wind River Range, "on a scale such as we have 

 not known in any other portion of the West." It is in these mountains 

 that, as alreadv mentioned, small active glaciers were also discovered bv the 

 same party. This range, which occupies, so to speak, the summit of the 

 country, being drained by the head-waters of the Missouri and the Colorado, 

 lies a little farther south than that of the Tetons. It is a very lofty and 

 rugged chain of mountains, but the precise elevation of its dominating sum- 

 mits has not yet been made known ; Fremont's Peak, one of the highest 

 of them, was roughly measured by the explorer whose name it bears, and 

 its height given as 13,-370 feet. 



The Black Hills, lying between the parallels of 43° and 45°, have been 

 explored by a government expedition, to which Professor N. H. Winchell 

 was attached as geologist. The highest point of this range appears to be 

 Harney's Peak ; its elevation is given at 9,700 feet. Nothing is said in the 

 official report * of this Survey in regard to past glaciation or the occurrence 



* Report of a Eecouuaissance of the Black Hills of Dakota, etc., made iu the Summer of 1S74. By William 

 Ludlow, Captain of Engineers. Washington. 1S75. 



