218 



BULLETIN OF THE 



For a purpose presently to appear, it is pertinent hero to introduce 

 an observation made by Prof. Hitchcock in the valley of Avalanche 

 Brook, a stream that, starting from the gorge between the Chimney 

 and Pamola, abruptly terminates the East Slide by sweeping away the 

 detritus at its foot, which the brook passes nearly at right angles. This 

 " valley," where we saw it, is only a rocky channel, heaped with bowl- 

 ders of all sizes. In the dry season there runs, half hidden among the 

 rocks, a rivulet, which, in times of flood, becomes a furious torrent, and 

 fills the banks. Says Hitchcock : '* We ascended the valley of Avalanche 

 Brook on the south side of the mountain, and .... found an immense 

 number of bowlders of Oriskany sandstone, many of them highly fossilif- 



crous We found none of these bowlders higher than the foot of the 



slide, although others have found them a few hundred feet liigher."* 



Among the other drift met with upon the slides, we found smoothed 

 and striated stones, scratched uniformly in the direction of their length, 

 and rounded at the angles. They are the first of their kind that have 

 been reported from Ktaadn. The best were as fine examples of what 

 are considered typical glaciated fragments as any that are figured as 

 such in geological works. The largest, weighing from ten to fifteen 

 pounds, were more deeply scored than the smaller; but being too heavy 

 to be borne many miles in our packs, they were unwillingly left behind, 

 and others of less weight were selected as specimens. Of two that wxre 

 brought away, one is a piece of hard trap rock (determined by Dr. 

 Wadsworth to be diabase) five inches long by two and a half at its 

 widest part,. and weighing twenty ounces. The other is a thin piece of 

 fine-grained argillaceous sandstone, seven inches by three and a fourth, 

 split from some larger stone that was not discovered. Of such striated 

 fragments not more than a dozen in all were found upon both slides. 

 They were rare exceptions among drift that showed no stria;. Accord- 

 ing to the testimony of books, and of several persons familiar with gla- 

 cial phenomena from their own observation, the specimens agree precisely 

 in character with stones worn at their angles, and grooved on their 

 faces, under the ice of existing glaciers. It is of course impossible to 

 conceive them to have been shaped and grooved simply by the friction 

 they would have suffered in descending by gravity down the slide among 

 the other debris. 



the summit ; and 5,215 ™ 1,106 =^ 4,109 feet, the hf^ight of the given point of the 

 ridge above sea level. It was below tliis point, it will be observed, that Do Laski 

 found his "upper fossils." 



* Prelim. Kep. Nat. Hist, and Geol. of Maine, p. 395. 



