Limestone Belts of Westchester County, N. Y. 217 
The essential continuity of these intercalated beds of 
mica schist with the intercalated beds of augitic and horn- 
blendic material along the coast proves identity of origin, and 
origin by sedimentation. It indicates also a small change of 
constitution in the beds as they extend in that direction. The 
plasticity occasioned in part of the latter, during the progress 
of the metamorphism, accounts for all that looks like eruptive 
phenomena, even to the broken feldspar grains found in a slice 
of the pyroxenyte of one of the so-called veins. There is no- 
where evidence of injection into or through cold rock 
the same arenaceous mica schist. The others are in the midst 
of, or adjoin, the noryte, dioryte, and chrysolitic rocks, and 
hence might be put down among the “inclusions” of the region. 
In addition, they have a northwest strike (N. 17°-40° W.) But 
this is the strike, in part of Cruger’s limestone area, and in a 
portion of the Verplanck belt, so that the twist is not confined 
tothem. And, among so extensive masses of rock that became 
same line, though disconnected by intervening rocks. The 
eee are some of the stratigraphical facts observed among 
them 
No. 4, at Centerville, has at middle on its east side the com- 
pact porphyritic mica rock, Cb, which is schistose directly adjoin- 
ing the limestone in the field west of the road, and has th 
strike of the limestone N. 47° W. But to the westward in the 
field (in which the limestone can be traced for 250 yards with 
a change of strike to N. 62° W.) the mica rock changes to 
hornblendyte and quartz-dioryte; and to the, sontheastward 
along the road, augite-noryte appears within a few feet of the 
limestone, both the feldspathic fine-grained (almost eryptocrys- 
talline) variety (Be), and the coarser dark variety. hether 
this latter change in the bordering rock is due to a fault or not, 
could not be ascertained ; it was not due to an intrusive dike. 
- 5 outcrops on the railroad at 5 (see map) and on two 
roads at 5’ and 5’’, with the strike N. 82° W. etween Mont- 
rose Station and this limestone at 5”, the rock is noryte, except- 
where the road turns west, and an outcrop of chrysolitic noryte 
(hypersthene rock) 135 yards west of Munger’s. Ei hty yards 
beyond the chrysolitic rock comes the outcrop of limestone. 
One hundred and fifty yards west of the small exposure of 
