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1903] VEGETATION OF THE BAY OF FUNDY MARSHES 173 
where beneath the bog, even beneath the great bogs at the head 
ofthe tidal rivers. Soundings through the bog are easily made, 
and they show that the depth of the surface of the marsh mud 
from the top of the bog increases from nothing at the head of 
tide down to 6 or 7 feet away from the high part. Not enough 
soundings are available, however, to prove whether or not the 
slope is gradual from the high marsh to the extreme heads of 
the bogs, but so far as they go the soundings show this to be in 
general the case. This is confirmed by the water levels in the 
canal of the Misseguash Marsh Company. Where the canal 
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Fic. 4.— Ideal longitudinal section the marshes from sea to upland, to illustrate © 
their origin, 
passes through the highest part of the marsh near Black Island, 
the surface of the mud in July was nearly three feet above the 
water level; two miles up the bog, however, with a very slight 
current in the canal, the surface of the mud had dipped under the 
water, and the slope between the two points was perfectly 
gradual. It is fair to conclude therefore that the surface of the 
mud slopes away continuously from tide-head to the extreme 
distal margin of the bog. The question now arises, why this 
slope, which carries the bottom of the bog much below high- 
water level? No doubt the answer is to be found in the sub- 
sidence of the land already spoken of. Each part of the under- 
bog mud must at one time have been the tide-head and the 
highest part of the marsh; the newer tide-heads would be nearest 
the present one, and they would be progressively older, and 
hence have been carried deeper by the subsidence, the farther 
they are from the present one. This condition is diagrammati- 
cally represented in jig. 4: 
