76 BOTANICAL GAZETTE [AUGUST 
without involving the. complications which occur in the broader 
intermorainic tracts as a result of subsequent changes in drainage. 
The general physical features of this area have already been 
described (4). An extended account and delineation of the geology 
and soils has been given by LEVERETT (17) and in the field opera- 
tions of the United States Bureau of Soils (20, 21). A diagram- 
matic representation of the successive positions of the ice border 
and the location of the peat deposits is given in fig. 1. 
The Canton peat deposit (fig. 8), like the Buckeye Lake deposit 
(fig. 3) farther southwest, is among the first and the oldest in Ohio. 
In both the basal layers of macerated plant remains represent 
accumulations of peat which probably began while the ice border 
was receding from its maximum position across Illinois, Indiana, 
and Ohio to about the limits of the Bloomington group of moraines. 
The growth of peat-forming vegetation in these two deposits 
followed soon after the recession of the ice sheet, before the drift 
had become drained by development of valleys on it. 
Two seams of clay in the Canton deposit are noteworthy. Their 
positions indicate that the early period of peat formation was at 
least twice marked by climatic disturbances. The presence of the 
two layers of clay between layers of macerated types of peat seems 
to show that the ice readvanced to near this point into territory 
that had been laid bare following the maximum extension of 
the glaciers. In these states the western end of the Bloomington 
group of moraines not only overrides the weaker ridges of the 
Champaign moraines, but also extends into the ground occupied 
by the Shelbyville morainic system which was formed at the 
culmination of the Wisconsin stage of glaciation. The clay was 
probably deposited along the border of the ice mass by the same 
agencies that contributed the coarser material at the margin of 
the moraine, while further out, in the water basins, sand and 
finally clay were left. The deposition of clay may have taken 
place chiefly during the retreat of the ice front, when climatic 
conditions had become much warmer. It is not improbable that 
these clay seams represent the loess material which is known to 
cap the earlier morainic systems of the Wisconsin drift. Much of 
the material from the loess covered plains may have been carried 
