( 8 ) 
the Coaster’s Harbor Rocks, Goat Island (as ascertained by a 
recent well boring), the Little Lime Rock and some submerged 
rocks southwest of it. To this series belong also the Lime Rocks, 
where layers of magnesian limestone are associated with purple 
slates. On the Little Compton shore the green slates recur, ex¬ 
tending from Brown’s Point to Church’s Cove. From the out¬ 
crops of these rocks in our harbor, we may infer that they orig¬ 
inally extended from the Little Lime Rock to Coaster’s Harbor 
Island, to Rose Island and thence to Castle Hill, occupying the 
entire harbor and the passage (indicated by the space included 
within this line). The great veins which traverse these rocks 
often abound in chlorite, with which occurs also a pink feldspar. 
The series measures from 500' to 2000'. 
Before proceeding, I ought to make mention of some rocks on 
the Narragansett shore north of the Pier, which are not represented 
on this island. They are mica schists, dark and light alternating, 
containing here and there rounded quartz pebbles and traversed by 
veins of cream colored granite some of which are very powerful. 
This series extends from Wickford south to Watson’s Pier and a 
mile or more inland. It measures about 1450' in thickness. Its 
position in reference to the other beds is somewhat uncertain, but 
it probably is not far from that of the protogines. At the north 
end of Rose Island and the southwest end of Coaster’s Harbor 
Island is a peculiar dark gray or black rock made up of large 
grains of quartz firmly cemented together by metamorphic action. 
It is properly a coarse metamorphic sandstone or grit. The same 
rock forms the entire western part of Sachuest Neck, overlying 
the flinty slate of the eastern portion, and contains here and there 
small seams of black slate with coal plants—one of which is the 
Annularia longifolia . This rock occurs also at Conanicut on 
the east side of Mackerel Cove, where it rests upon the protogine 
and forms a triangular, area. Its greatest thickness is about 750'. 
This is the lowest and earliest rock in this vicinity which upon 
palaeontological grounds we can refer to the carboniferous period. 
Apparently overlying this metamorphic sandstone we have in 
Mackerel Cove a mass of light and dark gray argillaceous schists, 
which cover the entire southern extension of Conanicut and extend 
as far north as Taylor’s Point above Jamestown. These schists 
