MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK 31 
PART 2 
GENERAL GEOLOGIC SETTING” 
This section deals somewhat briefly with the larger and general 
geologic features of the Highlands as a whole, including a short 
discussion of structural conditions and the nature of the Precambrian 
complex. 
DOPOGRAPHIC PEATURES 
The Highland region of southeastern New York is a rugged, hilly 
to mountainous zone, reaching maximum elevations of 1600 feet. It 
is characterized, especially in the northern and western part, by 
irregular mountain masses and lofty ridges separated by very narrow 
valleys, all having a general northeast and southwest trend, but with 
irregularities of form which have developed in part because of the 
complex structure of the region, in part because of differences in 
the resistance of the rocks to erosive action, and in part because of 
the effects of glacial action. The southern and eastern portions of 
the Highlands are rolling to hilly, and less rugged. 
The ridges are interrupted, not continuous, and are en echelon 
with regard to one another, with abrupt and frequently precipitous 
cliffs on the southern ends, the northern terminations being generally 
more gradual. Where, however, the Highlands terminate at their 
northern and western boundaries, they descend generally precipitously 
to the smoother rolling lowland of Paleozoic sediments. The contact 
between the Precambrian rocks of the Highlands and the Paleozoic 
sediments lying north and west of them is sinuous and interrupted 
in the extreme. 
This is due chiefly to the dynamic history of the region; the north- 
ern and western margins represent in most cases faultline scarps. 
Here the Precambrian crystallines have been thrust over and upon 
the Paleozoic rocks, so that in many places, where the contacts can 
be seen, the relations are clear (fig. 1). The generally abrupt and 
precipitous northern and western margins of the Highlands are due 
then in large part to thrust-faulting and to the more rapid erosion of 
the softer Paleozoic rocks upon which the resistant, harder Pre- 
76 A detailed description of the geology of that part of the Highlands 
included in the West Point quadrangle appears as ‘Bulletin 225, 226 of the New 
York State Museum, by Charles P. Berkey and Marion Rice. Those inter- 
ested should refer to this bulletin for an exhaustive discussion of the complex 
structural features and for the origin of the Precambrian crystallines in this 
area. 
