MICHIGAN ACADEMY OF SCIENCE. 39 



indicates that they formed part of the mainland in post-glacial times. 

 If all of the uncultivated plants growing upon them had in one way 

 or another reached them by crossing the intervening water, we would 

 expect to find on some of the islands plants well distributed which on 

 others were wanting because the seeds had never reached them and we 

 would expect to find that some of the plants well distributed in similar 

 soil on the mainland were altogether wanting on the islands. But what 

 we find is the reverse of this. (See Sandusky Flora, Ohio Academy of 

 Science, Special Papers No. 1.) 



In 1838 trees centuries old were killed by the water standing over 

 their roots and many others in 1858. This occurred about Sandusky 

 Bay, on Kelley's Island, Put-in-Bay, Middle Bass and along the shore 

 Itetween Port Clinton and Toledo. The early settlers could recall 

 many observations that showed the water in the first part of the nine- 

 teenth century was not so deep as it became later. 



The terminal portion of the Cedar Point peninsula at the entrance 

 to Sandusky Bay is formed of parallel sand and gravel ridges that 

 have been thrown up by great northeast gales occurring at times when 

 the lake was above its normal level. The ridge nearest the bay is 

 the oldest and that nearest the lake the youngest. By studying the 

 vegetation it has been possible to determine the approximate age of 

 each of the principal ridges. Beneath the wind-blown sand the ridges 

 contain stratified sand or gravel or shells of molluscs showing the 

 height to which the materials were thrown by the waves. Each of the 

 principal ridges was dug into in many places in order to ascertain 

 the maximum height of the aqueous deposits in it. These deposits are 

 at a higher level in the recent ridges than in the earlier ones. Dividing 

 the number of feet showing the difference in level between any two 

 of them by the difference in time of their formation in centuries gives 

 the number of feet per century that the lake has risen. It is about 

 2.14. (For a detailed description of these ridges see ''Formation of 

 Sandusky Bay and Cedar Point," published by the Ohio Academy of 

 Science.) 



Sanduskv, Ohio. 



