* 
* 
compass useless. 
224 T. N. Dale—Geology of Rhode Island. 
Rock and 22, there is about half a mile square here of uncertain 
age. At 47 and 48, the protogine is bordered by a narrow 
strip of highly inclined, siliceous argillyte; at 51, these rocks 
are seen in contact. e protogine becomes a compound of 
greenish feldspar and hyaline quartz, and the overlying rock is 
a stratified flint. From 61 to 50 there is a low cliff probably 
ue to a fissure. From 57 to 58, the two rocks are again in 
contact and at 52 and 54 small insulated masses of siliceous 
argillyte overlie the protogine. At 46, distinct strata dip 40°- 
50° W.N.W. crossed by vertical fissures running H.S.H.- 
10°-15° E.N.E. In the northern part the dip is high and un 
certain, but the strike in several places is clearly N. SW. 
tine. The point forming the east side of Brenton’s Cove 5 — 
a massive, dark purple, siliceous argillyte, with veinlets of ae | 
green serpentine, enclosing, at one spot, amorphous calcite, ane 
at 65, a bed of greenish gray tale several feet thick, W?" 
seems to recur at 64, where it is dark green and associated willl ~ 
asbestos and picrolite. Seams of serpentine are not infrequent : 
in that vicinity and the schist is somewhat plicated, but ¢ — 
old iocality of precious serpentine is now concealed.* Both on 
the north and south sides of the tract thin seams of black, SU — 
ceous argillyte occur. A little west of 63 the rock is very afB™™ 
ss box made of this serpentine was so magnetic as to render the — A 
