considerable importance in the case of recharge of well water even though the upper and lower 

 strata were hydrologically connected north of the edge of the clay sheet. This question needs 

 further study, both geologic and hydrostatic. 



GLACIAL 



Glacial deposits on the island have been ascribed to a number of advances and retreats 

 of continental ice sheets, some of which have not extended beyond the Sound but at least one 

 of which is believed to have covered the entire island. Despite these numerous advances, only 

 one interglacial period (Gardiners) has been described and only two terminal moraines are 

 apparent. These last are assumed to mark two stages in the latest ice advance (Wisconsin) . 

 The location of other moraines, if such there be, is a matter of some importance from the 

 hydrologic standpoint. 



Certain other features of the glacial materials and surface together with some features 

 of the lower strata are noted below. 



178 



