22 ROYAL SOCIETY OF CANADA 
merged stumps and peat masses have reached their present position 
by undermining through wave action rather than by subsidence. There 
has been, nevertheless, a recognizable sinking of the land, at least from 
New Jersey to Boston in post-glacial times, some of the beds on the 
south shore of Long Island having undoubtedly reached their present 
position by subsidence, their position being such that undermining is 
out of thé question.” 
“On the north shore of Long Island there are a number of salt 
marshes lapping up against a very sloping surface. Above the marsh 
level, but extending to the edge, is a thick growth of bushes. At the 
edge the bushes are dead, evidently killed by the action of salt water 
which reached the roots through porous soil, but the bushes are still 
practically intact, even to small twigs. Just inside the edge of the 
marsh the bushes, still nearly intact, are seen projecting through a few 
inches of peat, but a few feet further out in the marsh only the trunks 
remain, while at a distance of two or three rods from the margin only 
the stumps are seen. The case is analogous to that at Fort Hamilton 
as described by Lewis.” 
“Of the instances mentioned by Shaler and others in 
Massachusetts, those at Nantucket and Truro are perhaps the most 
prominent. The submerged stumps at Truro have, in part at least, 
reached their present position by undermining. I have not examined 
the Nantucket Jocality. There appears, however, on the whole, to be 
very little evidence of a post-glacial subsidence in this region, although 
Dr. T. T. Jaggar a few years ago concluded, from observations on 
wharves at Boston, that there had been a sinking of two feet during 
the past century.” 
“The tilted clays of the northern coast of New England, the 
so-called ‘ Leda clay’ of early geologists, rises from sea level at Boston 
according to Mr. Clapp, to 70 feet in the Merrimac Valley and over 
200 feet in the Androscoggin and Kennebec Valleys. This clay, how- 
ever, is almost certainly of Pre-Wisconsin age, and its tilting cannot be 
adduced as evidence of post-glacial tilting. So far as Mr. Clapp could 
determine, there has been little change of level in this part of the coast 
since glacial time, although some local clays, which may possibly be 
of Wisconsin age, are found 40 feet above sea level on the Maine coast.” 
Spencer (8) has directed attention to the peculiar construction of 
the great submerged coastal plain which extends from Cape Hatteras 
with a width of twenty miles, to Labrador with a varying width 
upwards of three hundred miles in extent. This great shelf has a 
maximum depth of upwards of 450 fect, but its most remarkable 
feature is the occurrence of numerous channels which, in general, 
