44 GEOLOGY OF OHIO. 
clay, all the Atlantic coast north of New York has been raised, although 
very unequally; the elevation increasing northward from fifty to sixty 
feet in southern New England, to one thousand eight hundred feet at 
Polaris Bay, Greenland. 
Professor i. W. Hilgard has shown that the country about the mouth 
of the Mississippi, during the Quarternary Age, changed its level a 
thousand feet or more, and the facts which he reports are altogether in 
keeping with those observed higher up the valley. The manner in 
which the Loess is spread demonstrates that the region where it occurs 
was covered with water at the time of its deposition, and we know that 
it was mainly the silt transported by the Missouri, arrested in its passage 
to the Guli—where it is now deposited—and diffused through quiet water, 
which, at one time, apparently, occupied the whole valley as far north 
as the Great Lakes. With these submergences, the filling of the lake- 
basin had, perhaps, nothing to do, for, as we have shown, the water it 
contained was fresh, and was, doubtless, derived from the melting of the 
slaciers and snow fields of the north. 
LAKE RIDGES. 
The old beaches which encircle the lakes have been fully described in 
our second volume, and the proof that they are what they are commonly 
called has been given at length. The mistaken notion that they are 
moraines is, however, still entertained by some persons who have not 
carefully studied them, so that it is, perhaps, desirable to recapitulate 
very briefly here the proofs that they are “raised beaches.” 
First. The true lake ridges, three or four in number, are found mark- 
ing the south shore of Lake Erie, up to the height of two hundred and 
fifty feet above its present surface, in horizontal lines, that conform to 
all the topography, precisely like the “ Parallel roads of Glenroy.” They 
are, in fact, contour lines on the surface, and hence water-lines. No 
glacier would give such uniformity of height and dimension, such hori- 
zgontality and parallelism to the terminal or lateral moraines, which it 
left as it shrunk in volume. 
Second. The lake ridges are composed of beach and not moraine 
material; that is, they consist of gravel and sand, the former water- 
worn and rounded, with sometimes sticks, leaves, and, it is said, fresh 
water shells. 
Third. Where the line of an old beach passes round a headland, or 
along a steep declivity, it becomes a terrace—as at Berlin Heights, 
Cleveland,etc. This would be necessarily true of a shore line, but never 
of a moraine. ANE A 
Fourth. The ridges sometimes rest on stratified sands and clays—as 
