72 GEOLOGICAL AND MINERALOGICAL NOTES. 



in situ to a depth of fifteen feet or more and from which 

 the disintegrated material can be shovelled out in the form 

 of ordinary sand. It does not seem necessary to account 

 f or the areas in higher levels where there is an absence of 

 glacial detritus by comparing them to stations on the 

 coast line where the sea has removed boulders and glacial 

 tili, and assume that the sea must therefore have produced 

 similar results at these higher levels. 



When the flood waters of the Champlain epoch, which 

 undoubtedly covered nearly all parts of New England, 

 subsided and the land surfaces were elevated in the Ter- 

 race epoch, doubtless many of the so-called inland sand 

 beaches and alluvial terraces were produced which are now 

 faintly recognizable in sonie parts of Essex County. 



According to the Powellian theory (Prof. W. J. Mc- 

 Gee) the sea bottom, being continually weighted down 

 with the detritus furnished during the Glacial, Champlain 

 and Terrace epochs, must have been depressed. The de- 

 nuded inland hüls and mountains which furnished this 

 detritus that built up the drumlins and kames and the 

 deltas at the mouths of the streams,— the outer lobes of 

 which have been cut away by the inroads of the sea, and 

 which are now seen in the forms of marine marshes and 

 clay beds, — being lightened of their loads, would natu- 

 rally become elevated. As the whole of Essex County is 

 simply a portion of the general coast line, we must look 

 farther inland f or the mountains which have become ele- 

 vated. The elevation of our county coastline in recent 

 geologic times is thus rendered improbable. 



From all observations made, the evidence points to the 

 conclusion that there has been a subsidence of the land 

 surface of this coast region in recent, or, more accurately 

 speaking, in post-terrace times ; and that this subsidence 

 is still in progress. The submerged forest growth and 



