GLACIAL DRIFT. 20/ 



blocks is quite extensive and comparatively level, it is fair to conclude that the trans- 

 portation has been affected by the glacier and not by frost. The latter agency, how- 

 ever, has very industriously operated upon both ledges and boulders in post-glacial 

 times, so that the shattered ledges, their fragments, and the fractured boulders form a 

 continuous field of angular debris over the whole upper cone of the mountain. 

 From these facts, the following conclusions seem legitimate : 



1. The glacial ice completely covered and passed over the summit of Mt. Washing- 

 ton in a south-easterly direction. 



2. It brought along a large amount of moraine rubbish and glaciated stones, which 

 were disposed in various hollows and convenient locations about the mountain, in the 

 same way that the ground moraine is distributed in the lowlands. 



3. Subsequently an immense number of large blocks of stone, taken from the north- 

 ern slope of the mountains, were transported to the summit (as well as beyond), and 

 left overlying the finer earth debris of a previous transport. 



4. Frost and gravity have been acting upon the boulders thus transported and the 

 ledges, so that every large block has been split up into smaller ones ; and this angular 

 debris entirely conceals from view the previously formed moraine, and the summit is 

 apparently destitute of soil. 



After the announcement of this discovery, it was objected by some 

 that these transported foreign stones might have been brought by team- 

 sters or by the railroad. It was said to be a common custom for the 

 men to place canvas over articles in their vehicles for protection, and to 

 fasten down the cloth by stones. On reaching the summit, the stones 

 would be thrown away, and perhaps the glaciated bits might be some of 

 the fragments thus transported. The boulders I found were not over 

 two pounds in weight. These would hardly be sufficient to hold canvas 

 down in a wagon in the teeth of the formidable winds often blowing at 

 the summit. Still, I thought it best to search further in localities not 

 reached by debris. About fifty feet below the summit, midway between 

 the railway and carriage-road, I soon found a rounded block of light gray 

 Bethlehem gneiss weighing ninety-one pounds, evidently the rock that is 

 common about Jefferson, but very different from the material composing 

 the mountain. It lay beneath other fragments of stone, partly embedded 

 in earth, and showed patches of the common yellow lichen of the summit 

 growing upon it, older than the date of the building of either road. I 

 therefore concluded that no human agency ever brought this heavy stone 

 and planted lichens upon it ; nor is it probable the ones first discovered 

 reached the summit except as borne by ice. Hence the proof of the 



