SANDUSKY BAY AND CEDAR POINT 205 
THe Biack CHANNEL. 
This does not properly belong under the head of submerged 
valleys but as it is popularly believed to be a remnant of some 
former stream, it seems best to mention it here. As the entrance 
to Sandusky Bay was much narrower in the early part of the 
19th century than now, it has been supposed that at an earlier 
date no opening existed there but the course of the Sandusky 
River was continued by the Black Channel and the outlet was 
at the farther end. This is disproved by the fact that glacial 
clay and even rock make a continuous barrier between Sandusky 
and Cedar Point. 
The Black Channel and the smaller channels running 
through the marsh do not follow the buried valleys. The latter 
pass under them and have no connection with them. These 
modern channels give outlet to the bay for the streams which a 
few centuries ago had separate outlets into the lake. They also 
serve to distribute the water over the marsh or carry it from the 
marsh when the wind raises or lowers the level of the bay. At 
such times the currents may be quite strong and this serves to 
keep them open and deep as they are. They may be compared 
to the tidal inlets in the salt water marshes. 
The Black Channel has had its present position for at least 
sixty years. It is not, however, very old because three centuries 
ago Pipe Creek and the streams farther east had no connection 
with Sandusky Bay. Then there was not a continuous marsh 
extending from Pipe Creek to Rye Beach but each creek was 
bordered by marsh separated from those on each side by dry 
land. 
CHARACTER OF THE Post-GLAcIAL DEPOSITS AT THE BOTTOM 
OF THE Bay. 
These have not been studied carefully, the aim having been 
to find the depth of the glacial deposits below the surface. In 
the West Huron marsh the material overlying the glacial clay is 
composed largely of the remains of marsh vegetation, black or 
dark brown, extending in places to a depth of twenty feet. In 
the submerged valley of Mill Creek muck was found at a depth 
of 32 feet of such purity as to show that a marsh once existed 
there. Sometimes on withdrawing the auger marsh gas bubbled 
up through the hole in the ice; on one occasion it issued in con- 
siderable volume so that when lighted it produced quite a blaze. 
In ‘this and other valleys in the bay muck has been found at 
various depths, but it does not constitute a large percentage of 
the material filling the valley. This must have been transported 
