£>e]Geer.] 
466 
[May iS, 
action above the foot of the hills, some 10 or 20 feet above 
the marshes. At the marsh level north of Powderhorn Hill 
in Chelsea we visited a claypit showing to a depth of more than 
10 feet a fine laminated clay with occasional drifted boulders, 
probably of marine deposition. 
One day in company with Prof. W. O. Crosby and Mr. Lund- 
bohm I studied several terrace-like benches on the sides of sev- 
eral drnmlins which had been previously observed by Professor 
Crosby ; but as we found that they had sometimes a considerable 
slope, perhaps 1 :10 or 1 :20,and were not developed in the great- 
est degree on the sea side, we agreed that they could not be of 
marine origin. 
Though the marine terraces cut in the drumlins along the ac- 
tual shore are very sharply marked, their cliffs 100 feet high and 
their bases covered with residuary boulders, it might seem possi- 
ble that terraces cut in such a loose material would not be pre- 
served from slipping down for any long period. Nevertheless the 
presence of benches on the drumlins at Boston, as well as the 
very conspicuous cut-terraces in drumlins at the late glacial Iro- 
quois beach on the south side of Lake Ontario, makes it very 
probable that if the land at Boston had really been submerged 
to a great depth, the limit of the marine erosion at least, and per- 
haps several lower levels also, would have been recorded on 
the drumlins by shore-lines easily distinguishable in many places, 
though perhaps somewhat downfallen. I am therefore quite of 
Mr. Upham’s opinion that the subsidence at Boston was slight. 
In full accordance with this is Professor Crosby’s statement, that 
while the till in the Boston basin consists in great part of fine, 
clayey material, the wide-spread modified drift above the marsh- 
level contains nothing but gravel and sand, thus indicating that 
above this level there was no large water body where the finer 
sediment could be deposited. 
Mount Desert Island. 
I am very much indebted to Professor Shaler for his kindness 
in accompanying me to Mount Desert and in introducing me to 
the interesting geology of that island. During our two days’ ex- 
cursion I had several opportunities to observe that, as Professor 
Shaler’s map shows, the glacial, probably marine sediment, and 
