444 A. Guyot—Physical Structure and Hypsometry 
they now have. This may also explain the possibility of the 
creek, below Prattsville, cutting through the western plateau a 
thousand feet higher than its level, when we conceive that the 
erosion was begun by a stream coming from a higher level 
than the present plateau. 
The Southern Catskills are far from having the regular features 
which characterize the Northern group; nor are the boundaries 
as well defined, except along the Esopus valley. The central 
mass containing the most continuous and elevated chains, from 
which flow the head waters of the Esopus on the north and of 
Navesink and Rondout Creeks on the south, occupies the town- 
ships of Shandaken and Denning. It is flanked on the east 
by several high chains running north and south, in Olive, and 
on the west by long ridges, extending to the southwest and 
northwest into the Delaware Basin, in Hardenburg. The ex- 
tent of this mountain tract from the Esopus at Olive City to the 
Delaware near Margaretville, at the end of the Drybrook ridge, 
is 25 miles; its width from the Esopus at Shandaken to the 
southwestern boundary of Denning is about 16 miles. 
e find here no interior plateau enclosed between high bor- 
der chains, The massive central chain, which bears the highest 
summit is accessible from all the surrounding valleys without 
crossing any high pass; but the roughness of the wild moun- 
tain torrents and the unbroken primitive forest make that access 
anything but an easy task. Though the direction of the main 
chain is about the same as in the northern Catskills, via: west- 
northwest and northwest, several important ridges run to the 
north and northeast, almost at right angles, a direction never 
found in the first group, and imparting considerable irregularity 
to the physical structure of the Southern Catskills. 
he main chain, beginning with the Slide Mountain, stretches 
west 22° north for 8 miles to the broad knob of Eagle Moun- 
tain, from which it turns at right angles, north 30° east, 4 miles 
to Balsam Mountain, and changes again, beyond the Lost Cove, 
to north 40° west in Belle Ayre where it terminates. The first 
two parts form a dark, high, unbroken wall of 12 miles, densely 
wooded, crossed by a single wood road, in the Big Indian, oF 
Helsinger Notch, 2677 feet. Few summits rise much higher than 
the general crest. They are, from east to west, the Slide Moun- 
tain 4205 feet, Hemlock Mountain, Spruce top 3567 feet, Fir 
Mountain, about the same height, Eagle Mountain 3560 feet, 
Balsam Mountain, south end, 3601 feet. Belle Ayre has 4 
milder aspect and descends to 3394 feet in its highest portion. 
he Slide Mountain, the culminating point of the Southern, 
and the highest of all the Catskills, is in many respects quite 
remarkable. It terminates abruptly on the northeast toward 
the deep valley of Woodland, or Snyder Hollow, showing signs 
