J^li'lstoci'iic ('JnilKJi'x of LriU'l. /)<'(rcrr. 33 
Both at \'iiu'y:ir(l Ilincn. Martha's Miicvaid. aiul at W Is 
IIoll on tlie mauihiiul. tin- actual sliorcz-trrraco is very well iiiai'kcd 
and the l)t>ach is covered with uuiuerous residuary Iwuhk-rs. wliile 
the cliffs often consist of unwashed till, which litis evidently 
never l)een su1)nierij;ed. 
Bostdii . 
In the neifihliorhood of IJoston I made excursions in coui|)auv 
M'ith ^I]'. Warren l^i)liani and examined t'spci-ially the surfaces of 
several drumlins without being al»h' to see any traces of marine 
action above the foot of the hills, some Kl or 2(1 fe<'t ali(»ve the 
marslu's. At the marsh le\'el iioi'th of Powdcrhoru hill in Chelsea, 
we visited a claypit showino- to ;i depth of more than 1(1 feet a, 
fine laminated clay with occasional drifted boulders, pi'obabh' of 
marine deposition. 
(Jne day in company with Prof. W.O. Crosby and ]\Ir. Lnndltohm 
we stutlied several terrace-like benches on the sides of si-veral drum- 
lins which had been i)revi()usly oliserN I'd liy pr(»fessor Crosbx'; !)ut 
as we found that they had sometimes a considerable slope, perhaps 
1:10 or 1:20, and were not develo})ed in the <>Teatest deuree on 
the sea, side, we agreed that they could not l»e of marine oriuin. 
Though the marine terraces cut in the druuilins along the ac- 
tual shore are very sharply marked, their cliffs 100 feet high and 
their l)ases covered with I'esiibiary boulders, it inight seem possi- 
bh' that terraces cut in such a loose material would not lie pri'- 
served from slipping down for any long period. Nevertheless the 
pr«'sence of benches on the di-umlins at Boston, as well as the 
very conspicuous cut-terraces in druudins at the late, glacial Iro- 
cpiois Iteach on the south side of lake Ontario, makes it nci'V })rob- 
able that if the land at Boston h:id really been sul)merge(l lo a. 
great depth, the limit of the marine erosion tit least, and perhaps 
sevei'al lower levels also, would have bt>i>n recorded on tiie di-uni- 
lins by shore-lines easily distinguishable in many places, thoutih 
[)erhaps somewhat downfallen. I am therefore ipute of .Mr. I'p- 
ham's opinion that the suiisideuce al l>oston was slight. in full 
accordance with this is professor Crosliys statement, that while 
the till in the l>oston basin consists in great part of tine, clayey 
inat(n-ial, the wide-spicad modified drift abov(^ the maish-level 
contains nothing liut gi'avel and sand, thus indicating thai aliove 
this level thei'c was no large water body where the (inei' se<liment 
could be d(>posited. 
