Sandusky Bay and Cedar Point 205 



The Black 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 

 m.arsh 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-Glacla.l 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 filhng the valley. This must have been transported 



