H. E. Dodge — Pleistocene Fossils from Mass. 103 



and this for the reason that they are found in the eroded face 

 of the drumlin often at a height of over fifty feet above the 

 present sea level. Even if dead they would not probably have 

 been elevated much above the present level of the sea in their 

 original resting place, when set in motion by the ice sheet, and 

 a somewhat lengthy journey in the ice would seem requisite in 

 order to allow them to have risen so high above sea level as 

 we now find them. In spite however of the long journey, 

 apparently necessary for elevation in the ice, the fragments, 

 with few exceptions, show little evidence of Glacial wear. Mr. 

 J. B. Woodworth has shown me two small fragments of Venus 

 mercenaries from the Winthrop Great Head cliffs that still 

 present faint glacial strise on the inside, yet the shells have not 

 been sufficiently worn to lose their surface markings or the 

 gloss of the interior. The specimens of Buccinum and 

 Ilyanassa are especially well preserved, being but slightly worn 

 at the apex of the spire and retaining their delicate surface 

 markings. 



I found each of these two shells filled with compact till 

 containing small pebbles, and in one case a fragment of the 

 shell of Venus mercenaria. If the shell had died in place 

 previous to being taken up by the ice, it might be reasonably 

 expected to retain in its chamber, even to the present time, 

 some of the bottom on which it had lived. Therefore I care- 

 fully removed the filling from the outer chamber of the Buc- 

 cinum but failed to find within any other material than clayey 

 till like that in which it was lying when found. 



The large number of small fragments of shells scattered 

 through the till in the lower half of the drumlin of Winthrop 

 Great Head would seem to indicate that much of the material 

 of which the drumlin is composed came from the same place 

 as the shells, for we cannot conceive how the onward moving 

 glacier could remove the shells without taking at the same 

 time a large part of the bottom on which the shells were grow- 

 ing. If so, then the materials of this drumlin and of much 

 of our drift, not only represents the amount of bed rock re- 

 moved by the ice sheet, but such rock waste plus a large amount 

 of the previously accumulated soil, river and shore deposits. 

 It may in this case even include much of the drift deposited 

 by the first ice epoch which has been undergoing secular decay 

 during all of interglacial times. At any rate the physical 

 character of the material in the face of this drumlin seems to 

 indicate the presence of much fine clayey matter, greatly 

 decayed and appearing very similar in nature to the brick clays 

 of Cambridge and Somerville, Mass. These brick clays on 

 fresh exposure present to view innumerable small vertical 

 joints which allow the clay to break up into small cubes. This 

 tendency to break along incipient joint planes appears much 



