GEOLOGICAL SURVEY OF THE TEERITOEIES. 265 



present level of the included lake was found to be 249 feet above datum. 

 The last of this series of lakes, which we have called Phelps's Lake, 

 after a hunter of the region, who had seen and reported it, is hemmed 

 in by three moraines, according to Mr. Taggart, the outer one 162 feet, 

 the second 244 feet, and the third 287 feet above the lake itself, there 

 being no special surface-feature near the moraines on their outer side 

 to which to refer these levels, as to a recognizable base. In this last 

 case, the canon forks above, and the two arms extend in opposite direc- 

 tions along the line of separation between the granites and the flanking 

 limestones. Each of the two glaciers, therefore, gathered, from the rocks 

 overhanging it, granites on one side and limestones on the other, so 

 that, after their junction, the central moraine of the united glacier con- 

 sisted of limestone, and we find small fragments of limestone filling the 

 low central portion of the terminal moraine, while its high flanks, which 

 received the material of the lateral moraines, are composed Of the 

 granites, which are less easily disintegrated, and are therefore mostly in 

 large bowlders. ISTo remnants were anywhere seen of any lateral moraine 

 deposits along the courses of the glaciers. It is possible that such may 

 be found by more careful search, but the slopes are here so steep that 

 most of their lower portions are buried in the tumbling rubbish, so that 

 we can have little expectations of such a discovery being made. 



A little south from the second large caiion south of Mount Hayden, 

 the limestones come forward to the front of the mountain, above the 

 granites, which shortly afterward disappear from sight altogether. The 

 length of the exposure of the granitic nucleus of the range is about 

 thirty miles. 



About eight miles below Leigh's Lake, its outlet, which we have called 

 East Teton Eiver, enters the Snake. A hundred yards back from the 

 opposite bank stands a high, rocky butte, known as North Gros Ventre 

 Butte. Its northern end consists mainly of Carboniferous limestone, 

 dipping about 70° N. 56° E., and containing many characteristic 

 fossils. Along the west face of the butte, none of the lower rocks are 

 visible, being buried under the Post-Tertiary whitish sandstones and 

 marls, inclosing fragments of limestone and chert, but no fossils,, of 

 which all the southern part of the butte is composed ; but, near the 

 northeast corner, the lower part of the series of older limestones presents 

 the conglomeratic texture so characteristic of the Quebec Group, on the 

 west side of the Teton Range and elsewhere, and it is probable that 

 they represent that group, though no fossils could be found. Beneath 

 this we find gray quartzitic sandstones, which are probably of Potsdam 

 age. 



This butte stands near the middle of the broad basin which has long 

 been known by the barbarous name of Jackson's Hole. This has a length 

 of about twenty miles, and varies from five to ten miles in width. This 

 includes portions of the different terraces, all of which are more or less 

 covered with sage-brush. Near the butte, large areas of the sage had 

 been burned off, and the grasses had grown up densely, forming fine 

 pasturage ; and on these we again encountered antelope, which had not 

 before been seen by us since we entered the Upper Madison Caiion. It 

 is said that, during the winter, when the grass is covered, they live upon 

 the sage itself. This plant was now full of seeds, and the innumerable 

 little chipmunks which burrow in the plains and hills were busy gather- 

 ing them, biting off the long spikes and stripping them from end to 

 end, passing them back and forth through the mouth, as one would an 

 ear of corn. 



The pebbles of the terrace-gravel have thus far been mainly quartzites. 



