76 GEOLOGICAL AND MINERALOGICAL NOTES. 



In texture this sand is very clean and quite even in size 

 of the grains, all but two tablespoonfuls of nearly two 

 quarts passing through a sixty-mesh-to-the-inch sieve. 

 The quartz grains are from sub-angular to well round ed, in 

 fact almost pearlitic in form, the feldspar grains are about 

 one in twenty, also well rounded ; there are a few plates 

 of muscovite, some of which are one-quarter of an inch 

 in diameter ; no hornblende or iron-bearing minerals have 

 been detected. Near the surface the sand is in many 

 places quite deeply discolored by limonile "wbichhas un- 

 doubtedly come from the drift on the surface. Sand from 

 the sand dunes of Plum Island, Castle Neck or Ipswich 

 Beach, are invariably composed of sharp angular grains of 

 feldspar, magnetite and a little quartz ; thus it will be seen 

 that the sand of this sand piain, upon comparison with the 

 wind-blown sand of the sea-beach, is found to be quite 

 unlike in its essential characters. 



Upon comparing the sand of the sand piain with the 

 well known tertiary sand on Gay Head and with the 

 Nashaquita ClifFs in Chilmark, Martha's Vineyard, they 

 are found to be identical in general character. From the 

 general trend or direction across the county from Ipswich 

 to the Merrimac River in Lawrence, of the remnants of 

 the sand piain, it is fair to presume that the Merrimac 

 River flowed down this valley in pre-glacial times to the 

 sea, covering a much larger territory than it does at the 

 present time. If the drumlins, kames, eskars and other 

 glacial drift were removed and the surface of our county 

 was restored to the condition that it was previous to the 

 glacial period, quite a large part of the central and north- 

 ern part of the county would present a nearly level piain 

 surface with the water-courses and streams meandering 

 through it with an occasional Monadnock or high, rocky 

 hill rising out of the piain. 

 JVov. 1894. 



