THE GEOLOGY OF CONANICUT ISLAND, R I. 
GEORGE L. COLLIE, 
Professor of Geology , Beloit College. 
WITH PLATE IV. 
The island of Conanicut is situated in the southern part of 
the area known to geologists as the “Narragansett Basin.” It 
lies midway between the city of Newport on the east and the 
mainland on the west. 
The territory comprised within this area has been the seat of 
profound dynamic metamorphism and this island situated as it 
is in the very heart of the basin has been the centre of the 
varied activities and forces affecting the region as a whole 
The island is nine miles long and averages less than one mile 
in width. 
The surface features though modified by glacial action are 
controlled by the character of the underlying rocks very largely. 
The topography belongs to two distinct types. The one is a 
smooth rolling surface unbroken save by a few prominences 
and ridges. This kind of topography is characteristic of the 
northern portion of the island and the western portion locally 
known as Beaver Head and Beaver Tail. The underlying rocks 
are mainly soft easily eroded schists, a rock which constitutes 
the chief formation of the island, the slopes of the hills fre¬ 
quently coincide with the dips of the rocks, or with the planes of 
schistosity. The whole topography of the region is gently slop¬ 
ing. The ridges and prominences which break the smooth out¬ 
lines of this topography are either local outcrops of siliceous 
conglomerate or dikes which have better withstood erosive 
action than the schists themselves. The other topographical 
type is a broken and rugged one. Long ridges with cliff-like 
sides, or bare, irregular dome-shaped hills, locally denominated 
“ dumplings, ” characterize this second type. The underlying 
