234 Rhodora [DECEMBER 
The evidence afforded by the Quamquisset bog in regard to coastal 
subsidence remains to be considered. A line of soundings along the 
longitudinal axis of the bog disclosed a brown Sphagnum peat contain- 
ing so many stumps and prostrate logs of Chamaecyparis that it was 
only with diffieulty that a spot could be found where the sampling 
apparatus! could be pushed down to the sandy bottom without encoun- 
tering wood. At the narrowest part of the bog, the center of zone D, 
and from here all the way to the water's edge, where the stumps shown 
in Plate 82? have been exposed by erosion, there are large stumps 
and logs within a foot of the surface. In this part of the bog the 
soundings showed depths from eight to fourteen feet, but in most of 
the holes the peat sampler encountered not the bottom, but wood. 
А bottom of moderately fine sand, like that found in the upper part of 
the bog, was reached by a fourteen foot sounding made at the extreme 
seaward edge of the marsh, at a point outside the escarpment, where 
the surface is about two feet below extreme high tide level. ‘This 
proves that there has been no undercutting of the peat by wave action. 
By wading into the water a short distance, at low tide, the peat bottom 
was found to be soft and yielding beneath the layer of gravel and 
boulders which the waves have thrown upon it. From zone D land- 
ward to the living Chamaecyparis trees the soundings varied from 7.5 
to over 15 feet. Two or three feet of this depth is above high tide level. 
In this part of the bog, also, difficulty was found in reaching bottom 
on account of wood, which in several cases was encountered at a depth 
of 15 feet. 
If we accept as the greatest depth of the bog the fourteen feet found 
at the very edge of the beach, and add to that depth two feet as the 
maximum height of the tide above the surface at the point where the 
sounding was made, we get sixteen feet as the depth to which peat 
extends below high tide level. It has already been pointed out that in 
Chamaecyparis bogs where the peat contains wood from bottom to 
top, the water table originally coincided with the floor of the depression. 
When peat commenced to form in the Quamquisset bog, the floor of 
the depression must have been at least at high tide level, i. e., sixteen 
feet higher than at present. We must admit, therefore, a subsidence 
1 The peat sampler used was that devised by Davis, described in Report Mich. Geol. 
Surv. for 1906, p. 317 
2 This photograph is reproduced through the kindness of Mr. A. Н, Moore, who made 
a special trip to Woods Hole in order to take it. 
