SALT MAESHES-PAST AND FUTURE 



ancestry, continues to exist, for who can say 

 but that the glaciers of Greenland and Alaska 

 and Spitzbergen, of the Alps and the Hima- 

 layas may not again wax and spread over 

 regions now in the temperate zone? May it 

 not be that the present is merely one of the 

 interglacial periods which have occurred again 

 and again during the ice age? Indeed, there 

 is reason to believe that some of the inter- 

 glacial periods of the past were even longer 

 than the interval of time which has elapsed 

 since the ice receded. 



In order to picture the land as exposed by 

 the receding glacier, we must not only strip off 

 the salt marsh, as well as all other evidences 

 of vegetable and animal life, but we must do 

 more than this, for, as we shall see, there is 

 every evidence of a former higher elevation 

 of the land in relation to the water. There 

 are also reasons for believing that as the land 

 sinks, the marsh, soft and uncertain as it 

 seems, is really more stable than the everlast- 

 ing hills, and maintains itself at the same 

 point. 



Some of the low oak islands in the marsh 

 are doubtless the tops of drumlins or of 

 smaller glacial hillocks, as is shown by their 



209 



