154 Rhodora [JULY 
“Under these circumstances we should, therefore, have had, during 
a considerable period of time, a continuous strip of land, except for 
the river outlets, all the way from New Jersey to Massachusetts, 
separated from the mainland by a body of water occupying the trough 
scooped out by the glacier, which, in its present depressed and widened 
condition, we now call Long Island Sound, but which was then a 
fresh water lake or broad river. Bearing these conditions in mind 
we next have to consider the still further subsidence of the Champlain 
Period, the re-elevation of the Terrace Period, and the depression 
which is again going on at the present day. It is evident that at 
some time during these oscillations of level the sea, having eaten 
away the coastal plain, finally reached the barrier of the terminal 
moraine, where this still remained as the connecting link between 
Long Island and Massachusetts. The moraine gave way in places, 
channels were formed and detached portions remained to form the 
islands which we recognize today as Block Island, Martha’s Vineyard, 
Nantucket and the host of other lesser islands which stream out 
from the end of Long Island towards Cape Cod and the Rhode Island 
shore, while the eroded portions are represented by the great sub- 
pd, ridges which are known as the Nantucket and other shoals.” 
.it is evident that our theory implies the continued existence 
of fend connection, between New Jersey and southeastern New Eng- 
land, by way of Long Island, during a sufficient period of time after 
the final recession of the glacier, for the pine barren flora to have 
spread and become established there. .. . Long Island, Block Island, 
Martha’s Vineyard, Nantucket, etc., as we now know them, have 
not been submerged since the final retreat of the glacier, and their 
separation into islands by the submergence of the intervening land 
is a comparatively modern phenomenon, due to the depression and 
erosion which are actively at work, and which have produced such 
conspicuous results during the historic period.”’ ! 
Dana, reviewing in 1894 the botanical evidence, said: “The migra- 
tion northward of the Pine Barren flora must have been during the 
latter part of the time of high latitude elevation. .... Each stage in 
. the retreat was a contraction of the area of perpetual frost, and a wid- 
ening of the range of tropical winds, ensuring further encroachment. 
In view of all the facts, it is probable that before the subsidence had 
1 Hollick, |. c. 196-201 (1893). 
