haydes.] GLACIAL ACTION MORAINES. 49 



somewhat the appearance of a bastion which has been worn quite 

 smooth. In the sides of it are depressions like pot-holes, evidently 

 worn out by the attrition of loose rocks against the sides as the water 

 flowed underneath the glacier. There are also points where vast masses 

 of granite have been removed from the sides of the mountain at a great 

 height, giving to the mountain-side the appearance of an ancient quarry. 

 For a distance of about eight miles the bottom of the valley will av- 

 erage one-fourth of a mile in width, with here and there huge masses of 

 granite projecting above the general level, showing very clearly that the 

 entire valley has been carved out of the solid granitic mass. The loose 

 morainal deposits are not conspicuous until we reach a point about two 

 miles above the Upper Twin Lake, where the valley expands out to about 

 a mile to one and a half miles in width. Here a low swampy bottom 

 commences, which was once, undoubtedly, a portion of the lake. On 

 either side are ridges of the glacial deposits ; these increase in size and 

 importance as we descend to the junction of the creek with the Arkan- 

 sas. On the south side of the lower lake a ridge extends from the 

 mountains down to the Arkansas Eiver, perhaps 1,000 feet high, just 

 south of the upper end of the lake, and gradually sloping down 100 or 

 150 feet in height above the bed of the river. This is a true morainal 

 ridge, and was doubtless formed by the crowding out on either side of the 

 loose materials as the great glacial mass moved down the valley of Lake 

 Creek. This morainal deposit undoubtedly laps on to the mountain-side 

 so that the nucleus of the upper portion of the ridges is granitic. The 

 drift deposits are not generally more than 500 to 800 feet in thickness, 

 and usually much less. The granite crops out in numerous places on 

 the sides of the ridge, showing most clearly that the greater portion of 

 its nucleus is granitic ; it also shows that the valley, with the surround- 

 ing terraced hills, has been worn down by erosion from an elevation 

 as great perhaps as the loftiest portion of the main range. The north 

 side of Lake Creek is a very irregular ridge, full of depressions, while 

 on the west side of these ridges are extensive accumulations of rocks 

 more or less worn, showing the direction of the moving force. Besides 

 the vast lateral moraines in the valleys of the streams, there are a great 

 number of what may be called terminal moraines, or detached ridges 

 that tend in various directions. Sometimes they extend a portion of the 

 distance across the valley at right angles to the lateral moraines, or 

 they may diverge at any angle ; the great quantities of loose material 

 attached to the glacier seems to have been dropped in quite irregular 

 forms as it moved down the valley. In one instance the granite crops 

 out at the east end of the Lower Twin Lake, about the middle of the 

 valley, and under such circumstances that the inference is plain that 

 the entire valley has been worn out of the solid mass of granite. One 

 of the main objects of our description of the morainal deposits is to 

 show the extent of the erosion which has taken place in this region, 

 and these outcroppiugs of granite are the remnants that are left as 

 proofs of the magnitude of this work. From Mr. Derry's house, on the 

 northwest corner of Lower Twin Lake, we have perhaps as good a 

 general view of this valley and its surroundings as we can find. As 

 we look to the south of west we see two front peaks, which are 

 shaped like eones, rising up to the height of 12,500 to 15,000 feet. 

 A little to the southeast is an unnamed cone, with a broader sum- 

 mit, rising above timber-line. Although these points or peaks ap- 

 pear to be independent, yet they are really portions of spurs or 

 ridges extending down from the main peak, which extends further 

 to the west and forms a part of the crest of the range, to which we 

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