36 ROYAL SOCIETY OF CANADA 
been formed concurrently with or subsequently to the breaking down of 
the barrier beach and it stands as positive evidence of the subsidence 
which brought about the formation of the salt marsh. 
It may be objected that the different rates of erosion as between 
the larger stream entering the ocean and the smaller stream passing 
into Chauncey Creek, would account for differences in size and depth, 
but when it is recalled that the main drainage channel is several feet 
deeper, and that it contains but a small volume of water except at high 
tide, while there is a tidal flow through the small channel as well, it will 
be found that the objection is not a valid one. 
The evidence given in the preceding account seems to show that 
there is no evidence of undermining by the ocean, and it is difficult to 
apply to this marsh, the explanation given by Fuller (p. 19) to the effect 
that marshes on Long Island have been so formed, and that they are 
therefore not to be cited as evidence of subsidence in the coast line. 
The Brave-Boat Harbor marsh is directly opposed to the conclusions 
thus reached. In the first place the thickness of the turf formed since 
the salt water had access to the area, is direct proof of the period that 
has elapsed since such flooding was first established, and an effort will 
be made in a subsequent page, to establish the actual time period for 
the growth of that turf. It should be further pointed out that the 
growth of vegetation and the normal process of silting would soon 
raise the-surface of the marsh much above tide water, were the latter 
testing upon a wholly stable base. On the contrary, there is a con- 
stant relation between the surface of the marsh and tidal flow, which 
has obviously been maintained from the very beginning of the flood 
period. While the growth of the bog as such offers no evidence of 
depression of the area in which it hes, the formation of the layer of 
marsh turf does give such proof, and in a way which cannot very well 
be denied. 
Comparison of Bog Formations. 
In the immediate neighbourhood of the two marshes, the history 
of which has been detailed, there are numerous bogs in all stages of 
formation. Some of them are protected from incursions of sea water, 
cnly by reason':of the dam afforded by the barrier beach, and were this 
Jatter to be cut, the bogs would speedily become converted into salt 
water lagoons or into salt marshes according to the circumstances of 
the case. Others are so remote from the shore line and at such superior 
level as to be altogether beyond the reach of salt water. Their course 
of development would, therefore, lead to the simple formation of peat 
bogs or their final passage into sweet meadows. All the bogs of this 
