S. V. Wood— Origin of the Loess. 391 
pearance as if it still retained the horizontal plane in’ which it 
originally congealed,” originated he does not offer any suggestion. 
Neither do I, but substituting its perennially frozen state for the 
perennially frozen state of the ground beyond the limit of the land- 
ice during the glaciation, we have the conditions which then obtained, 
and gave rise to the material described by me under the letter y; 
viz. the loam with angular fragments, land-shells, and mammalian 
remains; the intrusive cave earth; and the warp, trail, etc.; save 
that as the ice itself cannot generate the material, (as the frozen, rock 
does, by the slide bringing layers of this successively within the 
thawing limit,) the material is but very thin over the ice except 
where it accumulates in hollows of this, and on the lowest part of 
the slope, all there is of it having slid from the nearest rock surface. 
The other fact to which I invite attention, in this connexion, is 
that which forms the subject of a description by Prof. W. C. Kerr, 
in an article in the same American Journal for May, 1881, “On the 
Action of Frost in the Arrangement of Superficial Earthy Material.” 
He describes, and illustrates by many cuts, the material which 
covers and hides the rock surface in North Carolina, and which he 
says 1s present generally over the Middle and South Atlantic States 
of the Union. This, which is derived from the rock it covers, varies 
in thickness “‘from a few inches to twenty, thirty, and even fifty 
feet.” “It is found throughout the hill country and mountain 
section of the State (N. C.), passing eastwards into the Quaternary 
deposits.” Fragments of quartz, usually small but sometimes a yard 
in diameter, and fragments large and small of gneiss, hornblende, 
slate, and other underlying rocks, occur distributed through the 
material, though sometimes accumulating towards the floor of the 
deposit, just as M. de Mercey describes in the case of the flint éclais 
of the Picardy loam. After describing the evidence of the slide in 
which these beds originated, and stating that they presented none of 
the features by which glacial deposits are usually recognized, Prof. 
Kerr offers the following view of their origin, viz. : 
“As the earth is often frozen, in Canada and even Vermont, 
during severe winters to a depth of 8 or 10 feet, and as in Labrador 
and other subarctic regions the frost of the present winters pene- 
trates to a much greater depth, so. it is evident that during the 
prevalence of the great ice-sheet over the northern end ot the 
Continent, as far down as Pennsylvania, and the prevalence of an 
Arctic climate in those middle latitudes, the earth was annually 
frozen to a depth equal to the maximum thickness of these deposits. 
The alternate freezing and thawing of the saturated mass of decayed 
rocks, constituting the Pre-Glacial surface, would of necessity pro- 
duce just the movement and settling which are described above. 
That is, this freezing and thawing would give rise to precisely the 
same movements of the mass, and of the particles inter se, as are 
seen to occur in the true glacier, differing only in amount. In other 
words these masses were earth glaciers, and these deposits may be 
denominated frost drift, as distinguished from proper Glacial drift.” 
In my view of the case, this explanation of Prof. Kerr’s requires 
