1903] VEGETATION OF THE BAY OF FUNDY MARSHES 169 
have myself seen such stumps in position. The soundness of the 
wood shows how recent the subsidence must have been. Another 
fact important in this connection is the presence of a bed of 
peat twenty feet thick under eighty feet of marsh mud, as shown 
by a boring at Aulac described by Mr. Chalmers. The same 
observer has also found that in other places the marsh mud is 
underlaid by post-glacial clay containing shells of species still 
living in this region, though in clearer and quieter waters than 
now prevail in Cumberland Basin, and that this clay merges with- 
out break into the marsh mud. Grouping together these facts, 
the history of the marshes would appear to have been as follows. 
At a comparatively late post-glacial period, the land must have 
stood much above its present level.? At that time the present 
Cumberland Basin was a shallow lake around which peat bogs were 
growing; it received the waters of the seven small rivers still 
flowing into it, and emptied by a single narrow fresh-water chan- 
nel along the course of the present Cumberland and Chignecto 
Channels. The subsidence of the land (the same which has 
drowned the lower valleys of the St. John, St. Croix and other 
rivers of this region), allowed the tide to creep farther and 
farther up this channel until it reached the lake above, which it 
converted into a brackish, and later a salt, lagoon. At first the 
water would not be very muddy nor the tidal fluctuations great 
in the lagoon; but as the land continued to sink, the currents 
would become more powerful, erosion more active, and the water 
so muddy that marsh formation would begin around the margin 
of the basin and at the head of tide on the rivers. Thus, grad- 
ually, the conditions of the present day were brought about.’ 
7 Not necessarily over 80 feet, the greatest known depth of the marsh mud, and 
even much less if Chalmers (Report, 41) is correct in ascribing a part of this depth to 
——.. faulting 
epth of the channel to the sea is consistent with this view. The best 
Sareea gine (No. 354, “River Petitcodiac and Cumberland Basin” ) gives the 
st depth over a rock bottom as 514 fathoms at extreme low tide, or about 80 feet 
me high tide. A deeper channel may however exist in the mud or sand on either 
side of the rock bottom. 
important question arises as to whether this subsidence is still in progress. 
The evidence is conflicting, and the various students of the subject are not agreed. 
believe it is stil] in progress for these reasons : first, it is still going onin other parts of 
