GEOLOGY OF MOUNT MARCY 7 



Notwithstanding these exceptions the large features show the 

 great northeast structural lines, characteristic of the eastern Adiron- 

 dacks and due, as one is forced to conclude, to a series of block 

 faults, whose escarpments look away to the northwest and whose 

 dropped sides were proba'bly therefore in this direction. The faults 

 have probably superimposed a later structure upon an older one, 

 which is marked by the relatively broad and open and more mature 

 north and south depressions.^ 



The lowest point in the quadrangle is the one where, on the 800- 

 foot contour, the East branch of the Ausable river flows north 

 across the boundary. All the other streams, except the little Niagara 

 brook in the southeast corner, leave the area at altitudes above 1700 

 feet. The Niagara is on the 1340-foot contour, where it passes to 

 the south. 



The highest point is, as stated, the summit of Mount Marcy, 

 53z^4 feet. There is therefore an extreme vertical range of over 

 4500 feet. The gravelly plateau of North Elba, standing at 2000 

 feet and above, constitutes the most extended area of fairly flat 

 character within the quadrangle. Nothing is known of the depth to 

 bedrock in this portion but it may v/ell be as much as 300 feet. 

 The first rocky ledge revealed in the course of the West branch of 

 the All-sable river in the Lake Placid quadrangle is over 4 miles 

 north of the boundary of the sheet. 



The mountains are in many cases of dome-shaped outline as one 

 approaches their tops. Mount Marcy itself is a striking illustration. 

 From a distance it resembles an umbrella without the projecting 

 rod. Mount Maclntyre is much the same (see plate 14). The 

 ascent of neither presents any difficulties beyond the length of the 

 walk from the nearest shelter. 



The Gothics, on the other hand, culminate in a sharp narrow 

 ridge, and the: same is true of McComb, Dix, Colvin and a few 

 more. McComb has a little cone-shaped elevation or nipple, super- 

 imposed upon the general ridge, and is therefore easily recognized 

 from a distance. Nippletop mountain is another of the same out- 

 line and is somewhat higher than McComb. Pitchclr mountain is 

 a very steep and narrow ridge, between two faulted valleys, while 

 by way of contrast Table Top mountain well justifies its name. 



Escarpments. There are several precipitous escarpments within 

 the quadrangle. The Vv^est side of Niagara mountain, in the extreme 



^ J. F. Kemp, The Physiography of the Adirondacks, Popular Science 

 Monthly, March 1906, p. 199. 



