82 BOTANICAL GAZETTE [AUGUST 
and shrubs to extend rapidly the limits of their distribution. It 
is unwise, however, to venture more, since at the present time 
definite stratigraphic and botanical data from peat deposits of 
northern states have not been exhaustively studied, nor have the 
investigations of the later quaternary deposits of the eastern and 
southern coastal states been carried to a point where they could 
be definitely correlated with the peat beds of this glacial substage. 
There followed a wet period, during which the forest in the 
Kent deposit seems to have become submerged. The weight of 
the trees can scarcely have caused a sinking of the forest layer in 
this basin, since its depth is small and the underlying layers of peat 
material show no compression or disturbance. With the rise of 
the water table a layer of fibrous material from sedges and various 
other marsh plants began to accumulate above the forest stratum, 
but there soon followed a more rapid increase in the water level. 
The area became covered for a time with water. 
The period of change recorded so conspicuously in the Kent. 
deposit appears to be associated with the Lake Border glacial sub- 
stage. It is readily correlated with the time which elapsed when 
the front of the Erie lobe receded northward to the Port Huron 
morainic system. As the ice in its retreat uncovered the Ohio 
divide, inundation followed the escape of waters from the subse- 
quent melting of the ice masses. No clay, however, entered into 
the formation of the peat deposit. The Lake Border moraines are 
practically free from loesslike silts, and apparently they were not 
strong enough to spread a seam of clay over this basin. When 
peat accumulation recommenced, there was again formed a layer 
of macerated material, followed by a fibrous type of peat from 
sedges, above which appears a stratum showing small twigs and 
branches of shrubs. Once more the area had become cool and dry, 
too severe perhaps for the free spreading of forests. Probably 
many tree species were again driven southward and replaced by 
more open vegetation, such as grassy marsh and shrubs. This cool 
period meliorated in severity rather rapidly and became sufficiently 
temperate for forests, for in the uppermost layer of peat are the 
remains of tamarack (Larix sp.). The stumps of the trees are stand- 
ing in the peat itself. The present surface vegetation is a dense stand 
