SURFACE GEOLOGY. 23 
At Cleveland that portion of the Erie clay which lies above the river is 
finely laminated and without pebbles or bowlders, but beneath the lake 
surface, as shown by the excavation for the new tunnel, the clay is thickly 
set with fragments of shale, and contains a few small bowlders. These 
are composed of granite, greenstone, or crystalline limestone, brought 
from the Canadian highlands, and are usually ground off and striated. 
At the mouth of the old valley of Rocky river the bowlder clay rises to 
the height of 50 feet above the lake, and the laminated clay of the 
Cuyahoga valley is wanting. Twenty miles above the mouth of the 
Cuyahoga the base of the Erie clay is distinctly shown. It is there a 
remarkably tough, compact, gray hard-pan, wholly unstratified, and con- 
taining many rounded and scratched bowlders. It rests upon a mass of 
fine-grained sandstone, in layers of a foot or more in thickness. These 
have been much broken up by the ice, and the under part of the clay is 
thickly set with angular or partially rounded fragments. Where undis- 
turbed, the ledge of sandstone bears the characteristic glacial marks. 
Following the valley of the Cuyahoga from its mouth to the summit of 
the watershed at Akron, we find the following section of Drift deposits, 
which will show the relations of the Erie clay to the overlying members 
of the Drift series: 
No. 1. Gravel, sand, and bowlders, more or less stratified, and form- 
ing hills resting on the Conglomerate, but from which the materials 
have been washed down, covering No. 2. 
No. 2. Stratified sand and sandy clay; the latter in many remark- 
ably even and well-defined alternations, yellow, blue, and red in color. 
Thickness, 30 to 100 feet. 
No. 3. Finely laminated clay, without pebbles or bowlders; as a gen- 
eral rule, yellow where weathered, blue where its iron is protoxide. In 
two instances striated bowlders of Cuyahoga shale, which forms the 
rocky walls of the valley, were found imbedded in this laminated clay, 
evidently dropped into the position they occupy. The greatest observed 
thickness of this deposit is 90 feet. 
No. 4. Pebbly Erie clay, penetrated by oil wells 228 feet to rock bot- 
tom of valley. 
In the foregoing section, No. 1 represents a portion of the kames, or 
sand and gravel series of the highlands; No. 2, the lacustrine deposits of 
the upper Drift; No. 3, the laminated portion of the Erie clay; and No. 4, 
its pebbly aspect. The composition of the mass of Erie clay which fills 
the Cuyahoga valley will be seen from the section given below, taken at 
the well of the Standard Oil Company, in the city of Cleveland: 
