SUPPOSED EVIDENCES OF SUBSIDENCE OF NEW BRUNSWICK COAST. 61 
tide level, and thus just above the influence of the tides; and 
the subsidence of several centuries would probably drown these 
bog floors to depths distinctly below mean tide level. If, on 
the other hand, there has been no vertical movement of the 
coast for several centuries, while peat has been accumulating 
in these bogs, we can see why the fresh-water structures ap- 
proach, but seem in no place to exceed mean tide level . 1 The 
latest evidence from the peat bogs of New Brunswick, therefore, 
argues rather for modern stability than for modern subsidence. 
Old Beaches on Prograding Shores, with Crestlines Lo wer than the 
Present Beach. — A few places on the coast of New Brunswick, 
where, instead of retrogression, there has been for centuries a 
forward construction of the beach, offer opportunity to test the 
hypothesis of modern subsidence by a comparison of the crest- 
line altitudes of the older beaches with the newer . 2 Of two 
such localities described by Professor Ganong — Miscou Grande 
Plaine and Portage island, the former was selected for a visit, 
partly because of the interest aroused by Professor Ganong’s 
report on the plant ecology 3 and partly because the age of 
the beaches on Grande Plaine can be estimated with some 
approach to accuracy. 
As both Chalmers and Ganong have stated, Grande Plaine is 
a long triangular tract of sands at the northwest side of Miscou 
island. Hither for centuries have been swept the beach sand? 
and gravels that drift northward along the east side of the island. 
Rounding Miscou point, the shore drift comes to rest on the 
more sheltered beach of the Grande Plaine. Each successive 
storm of the first magnitude causes the construction of a new 
beach, a little outside of the former one. Thus there has growm 
up a sandy terrace which is over a mile wide, and is corrugated 
with ridges and swales. The outer, newer ridges are very 
l A larger amount of testimony on this point is, of course, desirable, before drawing 
definite conclusions. The value of this evidence depends also upon the assumption 
that the sphagnum deposits have had a continuous upward growth, rather than a 
horizontal growth out over the surface of pools, in the form of a mat, which might 
sink to the floor of the basin, after a time, in the manner suggested by Professor 
Johnson. I am unable to say how far the latter process has entered into the forma- 
tion of the peat deposits here described. 
2 D. W. Johnson: The stability of the Atlantic coast. Bulletin of the Geological 
Society of America, vol. 23, 1912, p. 740. 
3 W. F. Ganong: The nascent forest of the Miscou Beach plain. Botanical Gazette, 
vol. 42, 1906, pp. 81-106. 
