Tar
aboard his scalloper Ruth Lea from
sample RI. 1 is from a_ peat-covered
area reported to be at least 1 km? in
nent (Spartina) and a freshwater one
(twigs and pollen of spruce, fir, and
ples are from outcrops of the sea floor.
Other samples are smail (10 g orless),
perhaps because of washing during the
dredging operation. Although some
small samples may not represent in
situ. deposits, they are generally from
so near the sites of larger samples that
only a short distance of transport is
59 m on Georges Bank. The material
contained both a salt-marsh compopine; and frustules of freshwater dia-
toms)
(7/2).
Subsequently,
additional
samples of freshwater peat were obtained in trawlings by Captain Lepire,
and others were found in samples of
bottom sediments collected for biological and geological studies by ships of
the U.S. Bureau of Commercial Fisheries and of the Woods Hole Oceanographic Institution—U.S. Geological Survey program. One peat was supplied
by T. J. M. Schopf (Marine Biological
Laboratory at Woods Hole, Mass.)
from a dredging made by A. E. Verrill in 1874. Other samples were found
within cores from the sea floor taken
for engineering studies and for investigations of pollen succession. These
peats from the sea floor are supplemented and compared with others obtained in borings made on land or
in freshwater ponds during studies of
extent, indicate that many of the sam-
suggested. Sample BT 9A consists of
only 2 cm of thinly interbedded or-ganic debris and detrital sand; thus
some transportation occurred prior to
deposition at the coring site.
Most of the samples consist only of
fine-grained fibrous organic material
packed into thinly bedded masses containing few or no visible inorganic
grains. For convenience here, this type
of peat is given the general term ma-
trix, whereas the obviously reworked
organic fragments occurring in domi-
nantly inorganic sedimentare called debris. Samples RL 1
and RL 2 (Fig.
3B) contain pieces of wood as long
as 30 cm, which are partly to completely surrounded by matrix; sample
G 2198 is a piece of wood that at the
time of recovery was thought to have
come from a deeply submerged peat
deposit.
Twenty-three freshwater peat samples
are listed in Table 1. Analyses of pol-
len content, all in the form of pollen
diagrams, are reported in the literature
for eleven of these samples. Table 2
lists our readings of the more diagnostic pollens from these diagrams. In
addition, we made new counts for sev-
en samples and listed them in Table
42°
postglacial history (Table 1). The many
samples materially extend the information that was previously available on
the
distribution,
nature, and
age
of
freshwater peat.
The distribution pattern of the peats
(Table 1; Figs. 1 and 2) shows a high
degree of correlation with areas that
were glaciated. This is reasonable in
viewof the ability of glaciers to form
depressions by both erosion and deposition. Especially striking is the pres-
ence of four samples bordering Great
South Channel (Fig. 2). The fabric and
composition of till on nearby Cape
Cod indicate that a tongue of the Wisconsin glacier moved through this chan-
441°
nel (13). Some of the samples, how-
ever, are from unglaciated regions, and
presumably they are representative of
deposits on poorly drained topography
bordering estuaries and lagoons.
Many of the samples of peat from
the sea floor are small, but those collected aboard the Ruth Lea had estimated weights (on an air-dry basis) as
great as 100 kg (Table 1). The samples
were irregular in shape, but they broke
easily into flat slabs because of their
bedded structure. Usually one surface,
considered the top one, is more or less
riddled with the holes of boring organisms, chiefly the pelecypod Zirfaea
crispata L. [Fig. 3 and (12, Fig. 2)].
The presence of borings on only one
side of a ‘slab, the fragile nature of
the peat, the large size of some pieces
(to 60 cm), and the fact that at least
8 DECEMBER 1967
po
70°
20 KM
BS
__.
NEN
69°
40°
Fig. 2. Positions of peat samples (closed circles) and of oyster shells and Texas
Tower No. 3 (open circles) superimposed upon the topography of the sea floor
off Cape Cod (see crosshatched area of Fig. 1). Contour interval is 20 m to a
depth of 200 m; contour interval at greater depths is 200 m [from Uchupi (41)].
3ye
.
©
1303