38 SEVENTH REPORT. 



CHANGE OF LEVEL AT THE WEST END OF LAKE ERIE. 



E. L, MOSELEY. 



Abstract. 



« 



When the retreat of the glacier northward opened an outlet to the 

 east for Lake Warren, the water was so lowered that it occupied only 

 the eastern portion of the Erie basin. Subsequent tilting of the land 

 depressed the western portion of the basin relative to the outlet at 

 Niagara so that Lake Erie has gradually attained its present dimen- 

 sions. The tilting still continues and the lake is enlarging. The effect 

 of the deepening and spreading of the water is shown in many ways. 



The streams entering the lake have slack water extending quite a 

 distance from their mouths, in case of the larger ones several miles. 

 Near the mouth of each is a marsh. Streams have been examined in 

 the vicinity of Cleveland, Sandusky, Toledo and on the Canadian side. 

 When the lake was at a lower level the streams cut their valleys deeper 

 than would be possible under present conditions. A number of these 

 vallej'S extend more than twenty-five feet below the present lake level. 



Under Sandusky Bay the stream valleys extend miles beyond the 

 present mouths of the streams. They have been filled with soft mud 

 which can be distinguished from the glacial clay by examining the 

 bottom with an auger. Submerged valleys of all the streams within 

 five miles of Sandusky have been traced in this way. The valley of 

 Pipe Creek has been traced not only under the bay but under the sand 

 bar that separates the bay from Lake Erie and into the lake. The 

 mud accumulated in the submerged valley of Sandusky River south of 

 Johnson's Island is now thirty feet" deep. 



Submerged Indian graves have been discovered on Squaw Island 

 at the present mouth of the Sandusky River. Submerged forests have 

 been found at Put-in-Bay and in different parts of Sandusky Bay, in 

 one place extending out half a mile from the present shore. Submerged 

 stalactites or stalagmites have been found in four caves of Put-in- Bay; 

 in Daussa's cave, five feet below mean lake level. 



About Sandusky Bay several square miles of what in 1820 was for- 

 est or prairie land is now marsh. The entire enlargement of the bay 

 and connected marshes since 1820, due partly to subsidence, partly 

 to erosion, is something like twelve square miles. The shores of 

 Lake Erie have receded. This is true of Erie, Cuyahoga and Lake 

 counties, Ohio, and of the vicinity of Port Stanley, Ontario, in fact 

 wherever investigation has been made except short portions of the 

 shore in a few places. At various places about the lake roads have 

 been changed because of the encroachment of the water and orchards 

 and houses have been undermined. The average recession of the shore 

 west of the Pennsylvania line is probably not less than twenty-five 

 rods in the past century on both the south and north sides of the 

 lake but the data at hand are not sufficient for a good estimate. 



The flora of the islands of the Put-in-Bay group and Kelley's Island 



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