1879. ] The Formation of Cape Cod. 493 
and fifty feet above the sea. Another long series of ‘plains, vary- 
ing from one mile to five miles in width, and of similar height 
and southward slope with the foregoing, extends on the north 
side of these hills from Syosset forty-five miles eastward to River- 
head, and thence continues along the north branch of the island 
nearly thirty miles more to Orient point. North of these plains, 
along the whole extent of shore east from Port Jefferson, is another 
series of drift-hills which rise one hundred to two hundred feet 
above the sea, by which their northern side has been frequently 
washed away. This second moraine is also mainly composed of 
stratified gravel and sand with few boulders ; but in the vicinity 
of Greenport and Orient its material is changed to a very coarse 
unstratified deposit like the upper till. This series is very plainly 
continued north-eastward in Plum and Fisher’s islands, which are 
made up of hills of glacial drift like those near Greenport, with 
small areas of level modified drift at their south side. Thence it 
passes into Rhode Island at its south-west corner, and extends 
close to the coast seventeen miles from Watch Hill nearly to 
Point Judith, being very finely developed in a belt which varies 
from one-half mile to one and a-half miles in width, composed of 
coarsely rocky drift in hills and ridges one hundred to one hun- 
dred and fifty feet high. About two miles north-west from Point 
Judith this range sinks to the sea-level, and its further continua- 
tion is lost, probably because it turns southward into the ocean. 
Twelve miles to the south the continuation of the first range is 
lifted into view in Block island, a knot of very irregular drift-hills, 
which resemble those of Montauk in being composed of coarse 
gravel, sand and clay, distinctly stratified but often enclosing 
numerous boulders. We have thus two long parallel series of 
drift-hills, the most southern of them at the boundary of the gla- 
cial drift. Both appear to be terminal moraines of the ice-sheet, 
having been formed along its border, the southern range at its 
period of greatest extent, and the northern at some later time 
during which it halted in its departure. — 
The sea covers the next thirty miles in the line of continuation of 
these series of hills, beyond which both of them rise above its waves 
again, the northern forming the Elizabeth islands, and bending to 
the north-east and north on the peninsula of Cape Cod to near 
North Sandwich, where it turns at a right angle, and thence runs 
to the east through Barnstable and the other towns to Orleans, — 
