No. 275.] 
115 
They are the mountainous region called the Highlands, and compos- 
ed of primitive rocks; the slate and graywacke region of Orange coun- 
ty; the red sandstone and the trap rocks of Rockland county. 
The tertiary and alluvial deposits might also be classed as two more 
divisions, but their area is not so great or their physical features so strik- 
ing. The Highlands in Rockland and Orange are a continuation of 
those of Putnam and Westchester counties, and are similar in general 
aspect, in the kinds of rocks, and in their mineral products. The rocks 
consist of gneiss and hornblendic gneiss, granite, sienite, limestone, horn- 
blende, serpentine, augite and trappean rocks. The strata dip to the south- 
east at angles from 50° to 90°, but there are localities where the strike and 
dip are transverse to the general directions. The strata are intersected by 
seams transverse to the direction of the strata, and nearly perpendicular 
to the line of bearing, and at intervals of 100 to 10,000 yards. Dislo- 
cations and vertical and lateral heaves have occurred along many of these 
lines of fracture. The outcropping edges of the strata are not parallel 
to the line of bearing, but like the ridges slope gradually down to the 
northeast, while on the southwest steep escarpments range along the 
lines of faults. Many of these faults are upon an enormous scale, and 
render the tracing of narrow beds of rock of economical value a matter 
of no small difficulty. There are no continuous ridges of mountains of 
more than a few miles in length, in consequence of the interruptions caus- 
ed by dislocations and lateral heaves of masses of the strata. The hills 
of similar rocks succeed each other in echellon lines, which seem to have 
been caused by lateral heaves along the lines of fault. In consequence, 
of this, neither the line of outcrop nor the line of bearing is parallel to 
the general direction of the Highlands, but ridge succeeds ridge, each of 
which runs out and diminishes in height until it disappears below the 
rocks, which are generally considered of more recent origin. For ex- 
ample, a traveller passing in Rockland county from southwest to north- 
east, along the base of any of the large hills of a mountain, if he conti- 
nues his course without turning off to the east, around the point of a 
succeeding mountain, he will soon find himself in the midst of the High- 
lands. If he be travelling in the opposite direction along the base of 
one of the mountains, and continue his course, he will find himself re- 
ceding farther and farther from the mountains as he passes each succeed- 
ing terminating hill. If he be travelling on the northwest flank of the 
mountains, the reverse will hold true, and progressing southwest from 
Cornwall, New-Windsor, or Newburgh, he will soon find himself en- 
tering the mountains and following through the valleys, will emerge on 
the southeast face of the Highlands. These valleys are called " cloves," 
