208 GEOLOGY OF OHIO. 
ern part of the township, and having an altitude of 200 feet. Near 
Hlyria this south ridge divides into two parallel ridges, which turn up 
the valley of Black River and reappear in Carlisle, Haton, and Ridge- 
ville, there known as Chestnut Ridge and Butternut Ridge. Thence they 
continue easterly, with some interruptions and interlocking, till they 
reach Brooklyn, Cuyahoga county, and curve southward into the valley 
of the Cuyahoga. In Ridgeville, which has taken its name from the 
ridges, four distinct ridges have been identified, while another, the most 
continuous of all, passes further north through Avon. 
The want of uniformity in the elevation of the surface in different 
parts of these ridges is not greater than we should expect to find in the 
circumstances. No one who will examine the composition of the ridges, 
and trace their courses on the map, will doubt that they are contour 
lines inscribed upon the topography by the action of shore waves. But 
on all sea beaches we find that the materials thrown up by the shore 
waves, or blown up by the wind, rise to somewhat different heights in 
different localities, according to the exposure and to the abundance and 
fineness of the material. Where this is sand, it is not generally thrown 
up to any great height by the waves, but it is often caught by the sea 
or lake winds, and heaped up much beyond the reach of wave action. 
Hence the ridges were doubtless higher in some places than others when 
first formed, and this inequality may have been exaggerated by the sur- 
face erosion to which they have been exposed during the ages which 
have since elapsed. By surface erosion they have also been frequently 
cut through, and perhaps locally quite removed; and to this cause we 
must attribute many of the gaps and interruptions which break their 
continuity. 
The ridges parallel with the south shore of Lake Hrie are sometimes 
continuous with and run into terraces; that is, the waves cut steps, or 
notches, into the shore where it was abrupt and hard—washed up mate- 
rial and formed ridges along the same line where it was low and soft. 
In the same way we now see a cliff forming at Avon Point, and a ridge 
being raised between the mouth of Huron River and Cedar Point, Erie 
county. In some places, also, a terrace left by the old shore waves is 
composed of unstratified Drift clay. In such localities the declivity has 
been mistaken for a ridge, and from the nature of the materials compos- 
ing it some erroneous ideas have been conceived in regard to the origin 
of the lake ridges. Precisely such terraces as I have referred to may, 
however, be seen now forming near Cleveland, and at other points where 
the immediate shore of the Lake is composed of Drift clay. 
Drift Deposits—As has been mentioned, most of the surface of Lorain 
