sihaame 
that in many places 
disappearing gradually, and the whole 
ay.* 
2. Drift clay, or red clay.—This deposit was long ago 
ognized as a peculiar one, distinct from the drift-gravel at 
sand above it, and the coarse drift beneath it. It has been de- 
scribed by the geologists of the Michigan state survey as the “ter 
tiary clay of Lake Superior.” From its red color, which is one 
of its leading features, it is also-called by some “red clay.” [tis 
difficult to determine its average thickness, from the fact that, a 
feet above the water, whilst its top is covered by a considerable 
mass of drift sand. 
0 
into it—thus showing that both deposits, although of different 
materials, belong, nevertheless, to the 
fore that there is no real ground to consi 
part of the tertiary formation. 
* This deposit might, perhaps, seem hardly worth mentioning, were it not that 
its peculiar fannie and its ala ‘emind ~f similar deposit widely diffused 
t New England, especially in the districts of Vermont, where — 
it forms the most conspicuous feature of ¢ 
