100 Proceedings of the Ohio State Academy of Science. 



40-foot level is a fine-grained blue clay. The peat deposit is 

 thicker towards the south than towards the north side of the 

 island -". The vertical section indicates by the marly deposits at 

 the bottom of the series the presence of Characeae and Cyano- 

 phyceae ; -^ -^ above this a long interval of a sedge bog and finally 

 a Sphagnum-Cranberry bog. The bog developed as a marginal 

 formation in the old lake and at the time of the beginning of the 

 reservoir was more or less surrounded by the forest. Whether 

 there was b'ut the one or several Cranberry fields in the swamp 

 I cannot determine. The report of cranberries growing in the 

 northern part of Thorn Township, if correct, would mean either 

 the extension of the present bog over a larger area to the south 

 and east, or several small bogs. When in 1828 the old reservoir 

 was completed and the waters rose and covered the swamp, the 

 bog too was submerged. Near the shore, however, the lake as 

 now must have been shallow and the light spongy sphagnum mat 

 was soon enabled to rise to the surface. The current belief that 

 it was at first a floating island appearing now here now there in 

 the lake, seems unfounded. Mr. Gabriel Gritten, a man now 85 

 years old and hence five years older than the reservoir, lived in 

 Millersport at the time and remembers having been on the island 

 when he was a boy of eight. He says it was always where it now 

 is and was like the present island except that there were no trees. 

 . At the present time, in this restricted area, plants from a 

 southeastern center of dispersal and which have been in the Ohio 

 valley so long as to be recognized as endemic, have overtaken a 

 small company of stragglers of the last great northward retreat, 

 and the inevitable struggle for existence and supremacy results. 

 Surrounded by a mesophytic forest, v/ith meadows and fields 

 close at hand the disseminules of many species find their way 

 into the b'og. That many invaders have entered the field before 

 the soil was prepared for them is attested by dead or partially 

 dead maples, alders and Rhus scattered thru the meadow ; but 

 that in the main the invasion is successful is demonstrated by the 

 numerous copses of the same and allied trees and shrubs, which 

 finally become confluent and in time will usurp the whole area. 



