382 The American Geologist. December. 1001 
velopcd strata of clay range from al)oiit three-fourths of an 
inch to one and one-half inches in thickness, or even more. 
This, however, is only the general appearance ; for a closer 
observation shows that these strata, and, in fact, the entire 
body of clay, may be subdivided by bands of quicksand as 
mentioned above. 
Some of the deposits of quicksand are plainly observable, 
as those which separate the clay into layers of about one inch 
in thickness. The thin seams of quicksand separating the 
clay vary, but they seldom measure three-sixteenths of an 
mch in thickness. The general . thickness of the quicksand 
IS from a sixty-fourth of an inch, or less, to an eighth of 
an inch. Often the seams are so fine that they are not vis- 
ible to the unaided eye. But taking the clay and pulling it 
a^- right angles to tlie line of stratification will divide it per- 
fectly along the strata as if cut with a knife. At times 
sheets of clay from one to several inches in thickness fall 
from the roof of the tunnel like broad strips of rubber belt- 
ing. The clqy is very tenacious and can be peeled off the roof 
by the yard in almost any desired thickness, like the bark 
from a tree. 
The strata are horizontal in the greater part of the work- 
ings, but places are found where they have been more or 
less disturbed by wave action. Some places show cross bed- 
ding, and others are much folded. 
In no place has anything but stratified material been 
found, and that of the finest composition. At a few places 
fine sand has been found ; but the}- appear mainly as pock- 
ets. The amount of quicksand which enters into the compo- 
sition of the body of the clay varies somewhat from point to 
point ; but where more than the normal amount is present it 
becomes what is termed "short," i. e. it breaks readily and is 
not easily supported by the compressed air. 
It may be stated here that all work is done under a press- 
ure of about two atmospheres. This supports the clay in 
the roof and keeps it from coming in at the face, besides 
keeping in check the gas which is found more or less through- 
out the clay. 
The following analyses were made by Prof. A. W. Smith, 
of the Case School of Applied Sciences, Cleveland. No. i is 
