SANDUSKY BAY AND CEDAR POINT 207 
turn the auger through six or eight inches of sand. From here 
on the sand increases rapidly. A quarter of a mile south of the 
Rear Range Light we bored through six feet of it without reach- 
ing the bottom. The layer of sand found between a mile and a 
mile and a quarter north of the city is not at the surface of the 
mud but a few inches below it, while several feet of mud inter- 
vene between the sand and the clay. As long as the entrance to 
the bay remained narrow it is probable that great waves travers- 
ing the lake were checked enough there to prevent sand being 
carried so far toward Sandusky, but when the washing away of 
Spit Island widened the opening much of the obstruction was 
removed and the great storms of about 1860 distributed sand 
(some of it, no doubt, derived from Spit Island) farther in the 
bay than it had come before. In later years the narrowing of 
the entrance by the construction of a submerged jetty extending 
northwest from the Outer Range Front Light as well as the 
scarcity of great northeasters may have prevented further 
accessions of sand and given time for mud to be deposited on 
top of that which was left here in former years. 
We have never found thick deposits of sand except where 
it had apparently come in from the lake. The bar west of 
Biemiller’s cove has much sand and gravel which has been 
moved along shore from the north, but a short distance west of 
the bar the sand forms only a thin surface layer. 
WORK OF THE GLACIER AND PREGLACIAL 
CHANGES. 
The glacier rested heavily on the region about Sandusky 
and left its impress on the rock in many places, the grooves of 
Kelley’s Island and Marblehead being larger than are known 
elsewhere. Near the north shore of the bay large grooves 
have been noticed north-east of Hartshorn’s dock and at the 
Ohlemacher quarries. Al sng the south-east shore of Johnson’s 
Island are numerous disiinct grooves extending beneath the 
water. On the higher ground back from shore they are con- 
tinually being uncovered in stripping the rock as the quarry is 
extended and a number of fine ones have been quarried away in 
the last three years. In the city of Sandusky wherever. the 
overlying clay is sufficiently deep to protect the rock from 
weathering, its removal discloses glacial marks. Near the bay 
we have noticed them at the Ship Yard and in the basement of 
Emerich’s drug store. In the summer of 1904 when the founda- 
tion was being prepared for the concrete work at the foot of 
Columbus Avenue, a piece of limestone showing plain glacial 
marks was broken off twelve feet below the surface of the water. 
