176 E. Andrews on the Western Boulder Drift. 
square miles. The hills are often sharp and conical and inter- 
spersed with deep circular valleys without outlets, from which 
the region has obtained the popular name of ‘‘ The Potash 
Kettles.’ In the northern part the gravel is very coarse, many 
of the pebbles being more than a foot in diameter, and yet 
well water worn, and thrown up into steep round hills so lofty 
as to imply great violence in the water action that threw them 
up; but as we trace it southward the material becomes finer 
and the hills lower, until they shade off imperceptibly into the 
drift clay of the Illinois Prairies. The stratified character of 
the gravel, though often obscured by the coarseness of the ma- 
terial is on the whole too evident to admit of any possible 
oubt, as in innumerable places it exhibits both stratification 
and cross-stratification in the plainest manner. On the oppo- 
site or northwest slope of the valley no such gravel formation 
exists. It would seem to be an unavoidable inference that our 
It is interesting to notice that a similar gravel range flanks 
the : tern border of the valley of the Georgian Bay, 
which juts out southeast from Lake Huron. This is described 
by Rev. Thos. Hurlburt, of Caistorville, Ontario, Canada, In @ 
paper to the Chi Academy of Sciences, not yet published. 
Another fact which shows the aquatic character of our drift 
agencies, is that the gravel hills, as well as nearly all the other 
drift of this region are covered with a thin stratum of orange- 
colored loam, which varies from a few inches to several feet 12 
i oats ahs 
