434 A. Guyot—Physical Structure and Hypsometry 
The mountains, therefore, whatever be their external forms, 
as well as the surrounding plateaus, are masses of piled up 
strata, with a slight inclination to the south or southwest and 
northwest, often hardly perceptible. A greater disturbance 
from the horizontal position is seldom observed and, when 
found, is only local. To this disposition of the strata and their 
tendency to break by the joints at right angles to the planes of 
stratification we must trace the occurrence of those abrupt 
ges which are so frequently encountered by the traveler, 
and are often a cause of serious difficulty and no little danger 
to the inexperienced mountain climber. This also explains 
why the tops of the mountains are not pointed peaks but 
mostly flat surfaces, often of considerable extent, and why it 
is only at the edges of these that are found the perpendicular 
ledges which border precipices of vertiginous depth and dis- 
close the splendid views which have rendered the Catskill 
Mountain House and the Overlook Mountain so celebrated. 
To the same cause, again, and to the peculiar mode of disinte- 
gration of the strata by successive steps, are due the numerous 
cascades which are so characteristic of the Catskills, and one 
of their greatest attractions. 
Most of the peaks measured were, as usual in American 
wildernesses, without names. I had to find some fitting 
pombe Those in use, such as Roundtop and High Peak, 
orth and South Mountains, are so often repeated in all parts 
of the Catskills that to prevent confusion it was sometimes 
necessary to change or to qualify them. In the new ones I 
tried to avoid the fanciful names so much in vogue, and to 
derive them when possible from their geographical location. 
To Roundtop at the head of Little Westkill I applied the 
old Indian name of the region, Ontiora. Roundtop at the 
head of Drybrook became Doubletop, a name which from its 
form is more appropriate; South Mountain close to it is called 
on the map Graham Mountain, in honor of its owner, one 0 
the old settlers of that district. In the Catskills nearly all 
valleys and passes are called hollows. 
The Central Chain is, as before mentioned, the longest, the 
most massive, and plays the part of a back bone for the whole 
Catskill region. It forms at the same time the southwestern 
border chain of the Northern Catskills. Its total length from 
the Overlook Mountain, its southern end, to the Utsyantha, 
in long slopes and heavy spurs toward the south and west, 
while it falls abruptly toward the interior to the northeast. 
