430 A. Guyot— Physical Structure and Hypsometry 
exception of the bottom and slopes of a few valleys and of 
some portions of the northeastern plateaus, it has remained so 
to this day. 
The wilderness of the Adirondacks is more extensive but 
hardly more complete than that of the pathless forests of the 
Southern Catskills, the habitual haunts of numerous bears, wild 
cats and occasional panthers. Add to this the fact that most 
of the mountain tops, not to say all, are not sharp peaks, but 
extensive thickly wooded flats from which no distant views can 
be obtained and it may readily be understood what difficulties 
lie in the way of the topographer and why ordinary surveys 
stop short of the mountain chains. 
And still several features of the Catskills are well calculated 
to excite in a high degree the curiosity of the scientific inves- 
tigator, and to call for a thorough study of its plastic forms. 
Though situated in the midst of the Appalachian system, and 
evidently a part of it, it appears in it as an anomaly. While 
the Appalachian ranges, throughout the system, invariably 
trend from the southwest to the northeast, all the chains of the 
Catskills ran in an opposite direction from the southeast and 
east to the northwest and west. 
I have shown elsewhere in this Jou‘nal, the existence of 
transverse chains, in the Appalachians of North Carolina and 
Georgia, reaching 5000 and 6000 feet between the Blue Ridge 
and the Great Smoky Mountains. But these two great border- 
chains at least retain the normal direction, while, in the Cats- 
kills, even the border-chains run at right angles to the system. 
Again, while the neighboring Appalachian chains, the Kitta- 
tinny, or Blue Mountains, in New Jersey, hardly reach 1800 
feet, and their continuation, the Shawangunk, rarely excee 
2000 feet (Sam’s Point 2341), the group of the Catskills sud- 
denly rises to double that height. On the east, beyond the 
valley of the Hudson, the Green Mountain ranges remain lower 
by 1000 and 1500 feet. On the north, beyond the deep valley 
- of the Catskill Creek, the plateaus average less than 2000 feet 
and on the west the swells of land, around the sources of the 
Delaware and Susquehanna, do not much surpass that average 
their highest points seldom reaching 2400 feet. The Catskills 
stand as a mighty citadel overtowering by 2000 feet all the 
surrounding country. 
These apparent anomalies in the otherwise regular structure 
of the Appalachian system need an explanation. The first step 
toward it was to obtain a correct idea of the topography an 
orography of the region, and of the direction and altitude of its 
mountain chains and valleys, which no existing map could give. 
To this work the writer has devoted several summer vacations, 
from 1862 to 1879. The results of these observations are 
