202 Out1o State ACADEMY OF SCIENCE 
Map IV. 
Buried Valleys under Sandusky Bay. Compare with Map III. 
Bridge station giving outlet to the water from the Rockwell 
springs and formerly the other bold springs at Castalia. By 
means of a canal the water of these other springs has been 
diverted to the stream that discharges at Venice. This stream 
five hundred years ago extended nearly two miles farther north- 
east than now, joining Mill Creek about 82 degrees, 45 minutes 
W. longitude, 41 degrees, 28 minutes N. latitude. The former 
course of Mill Creek has been worked out in detail but near its 
confluence with Sandusky River south of Johnson’s Island its 
location is not entirely certain. Here the river valley was prob- 
ably so deep below the surrounding country that even short 
tributaries cut deep ravines on approaching it and the multi- 
plicity of these makes it difficult to work out the ancient 
topography in detail. 
Between Mill Creek and Pipe Creek no important streams 
enter the bay nor do the numerous borings indicate that they 
were ever here. North of Sandusky the surface of the clay 
slopes gradually toward the former course of the river. 
East of the Pennsylvania Railroad dock a little creek for- 
merly entered the bay. Its water is now carried by Whiskey 
Run sewer. The valley was easily traced as far as the dock but, 
owing to its small size and the fact that its banks were cut down 
by the waves of the bay, I was long puzzled to know what 
became of it beyond the dock or dredged channel. Certain 
