384 The American Geologist. December, looi 
, mouth. In the construction of one of these tunnels, what was 
apparently the channel of the old Cuyahoga was found at a 
depth of about eighty-five feet below the surface of the lake. 
A description of the preglacial valley of the Cuyahoga 
river was given in the American Geologist, September, 
1897. By way of explanation to the following, it may be 
stated that the records of numerous wells drilled in Cleveland 
and vicinity, show a deep V-shaped preglacial valley empty- 
ing into lake Erie. The deepest part of this old valley, as 
determined by its rock walls and bottom, is about three and 
a half or fcur miles east of the present mouth of the river, 
and has a depth of about 450 feet below the lake level. The 
east side of this old valley is quite abrupt. From the deepest 
part its west side rises gradually and outcrops a short dis- 
tance beyond the mouth of the river. This preglacial valley 
has been traced back from the lake front about nine miles. It 
i? now entirely filled with a sedimentary deposit, over and 
through which the present river flows. It is probably in this 
deposit which extends under lake Erie that the old river course 
was discovered. This old channel, which is described below, 
is over eiglity feet below the present lake level. 
The best idea is obtained from a part of the report of Vc\- 
un:e 16, as follows : 
"When the test holes were bored in the clay along the line 
of the tunnel, care was taken to sink them far enough away 
from the proposed line to avoid any danger of running the 
tunnel near them, in case the crib could not be located upon 
the spot designated. The outer boring was made about 300 
feet westerly from the crib, and the clay brought up was of 
the best quality for tunneling in ; and that under the crib is 
believed to be only a pocket or narrow valley in the original 
deposit, subsequently filled by clay sediment, and not yet solid- 
ified, though having precisely the same appearance as the 
harder clay when dried. In building the shore end of the 
tunnel two such deposits were passed through, the soft de- 
posits first appearing at the top of the excavation, and inclin- 
ing at such an angle that after digging but a few feet the wliole 
excavation was in this soft clay; this was continued (with the 
exception of a narrow ridge or island of hard clay reaching to 
about the center of the tunnel) for a distance of about 300 feet 
