168 Prof. J. D. Dana — Metamoiyhism of 



are represented to the northward hy bands ten feet and less to over 

 thirty feet in thickness, of a bhick fine-grained mica-schist, very 

 pyritiferous. Going from the Point, the first outcrops of interstrati- 

 fied schist and limestone occur after an earthy interval of 300 yards, 

 and here the mica-schist is hornblendic, a feature it loses to the north- 

 ward. These beds of mica-schist have just the positions of most of 

 the supposed "veins," and appear to be their more northern portions ; 

 and further, among the more northern "veins" of the Verplanck 

 shore, some are simply mica-scMst. Such facts explain also many of 

 the vein-like bands of Montrose and Stony Points. The difi'erence 

 in mineral constitution between such interstratified beds to the north- 

 ward and on the shore is what should be expected ; for the limestone 

 is bordered to the eastward in the one case by true mica-schist, and, 

 in the other, by augitic or hornblendic beds ; and the associations at 

 Montrose and Stony Points ai'e similar. This view is also sustained 

 by the occurrence in the limestone near the schist, 1000 yards from 

 the Point, of coarse spots of pyroxene with mica and chlorite, rudely 

 in layers, which must be due to the original deposition of impurity 

 and metamorphio action. The augitic rock (pyroxenite) on the east 

 of the limestone at the Point outcrops (owing to excavations in the 

 drift) for 200 yards from the shore ; but its place beyond this con- 

 tinues covered for three-fourths of a mile, and here the rock is 

 arenaceous mica-schist ; the spots of pyroxene are its only 

 representative. 



The essential continuity of these intercalated beds of mica-schist 

 with the intercalated beds of augitic and hornblendic 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 metamorphisra, accounts for all that 

 looks like eruptive phenomena, even to the broken felspar grains 

 found in a slice of the pyroxenite of one of the so-called veins. 

 There is nowhere evidence of injection into or through cold rocks. 



(4) Vicinity of the smaller limestone areas of the Verplanch Peninsula. 

 — Six small limestone areas occur in the Yerplanck peninsula. They 

 are lettered on the map 1 to 5 and j. Number 3 has the strike of 

 the large Verplanck belt, and has about it the same arenaceous mica- 

 schist. The others are in the midst of, or adjoin, the norite, diorite, 

 and chrysolitic rocks, and hence might be put down among the 

 " inclusions " of the region. In addition, they have a north-west 

 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 to them. And, among so extensive masses of 

 rock that became plastic or fused in the era of upturning, this 

 abnormal position of included strata is not strange. Numbers 2 and 

 5 are probably parts of the belt ; and numbers 1 and 4 may be in 

 the same line, though disconnected by intervening rocks. The 

 following are some of the stratigraphical facts observed among them. 



No. 4, at Centerville, has at middle on its east side the compact 

 porphyritic mica rock, Gb, which is schistose directly adjoining the 



