SURFACE GEOLOGY. 63 
The bluff of the river is 250 feet above the Lake. An irregular clay ridge is a half 
mile north of the bluff. This is 260 feet above the Lake, and is composed of bowlder 
clay, with a surface somewhat irregular from the effects of erosion, but gently sloping 
to the sandy ridge, D, on which Madison village stands. From this point there isa 
rapid descent to the level of the railroad, the incline beyond being so gradual that the 
surface appears quite level, until the gravelly ridge, C, is reached. Between D and C 
the soil is agravelly loam, with some clay. Near the ridge, C, itis somewhat swampy. 
The ener slope from B to C is very regular, but the surface is much diversified by 
sand dunes and stretches of marshy land. ‘The ridge at B is made of fine, water- 
washed and drifted sand. The north ridge, B, continues from Madison to Painesville, 
and consists of irregular sand dunes, constantly changing in form under the influence 
of the wind. Where undisturbed, it is from 10 to 12 rods wide, with a gentle descent 
on each side.” 
SECTION OF SOUTH RIDGE, PAINESVILLE, OHIO. 
or nlm 
. oh 
. 
oS 029-6 
£5 oO yo 
Coarse unstratified gravel, r2 feet. 
=] Fine stratified gravel, 4 feet. 
SS) Coarse gravel, obliquely stratified, 6-12 feet. 
»:+| Fine gravel, with irregular waved lines of stratification. 
QRIGIN OF THE LAKE RIDGES. 
In the preceding notes on the lake ridges so much evidence has been 
furnished that they are raised beaches, that little more need be said on 
this subject. It is, however, necessary that I should make brief reference 
to some theories that have been published in regard to the mode of forma- 
tion of these ridges, and which are inconsistent with the views I hold. 
Of these theories, one is that advanced by Col. Chas. Whittlesey, who has 
gathered and published a vast number of interesting facts connected with 
the Drift of the Western States, that the lake ridges are sub-aqueous bars 
which were formed in the Lake, parallel with the shore, when the water 
stood at higher levels than now. The considerations which prevent my 
acceptance of this view are: First, that they show too much continuity, 
regularity of form, and uniformity of level, to have been produced in the 
manner suggested. Sand-bars, as we know, form off the mouths of rivers, 
and these, sometimes, have considerable linear extent; but so far as my 
knowledge extends, no sand-bars exhibit anything like the extent, con- 
