merged off the southeastern coast of
New England as the result of the postglacial worldwide rise in sea level. The
exposed broad coastal plain of low relief provided abundant shallow sedimentary basins in which the gradual
Detailed quantitation and integration of chronological and palynological data have not been available for
assigning precise values to the latitudinal retreat of the boreal forest during
the period of climatic amelioration that
began about 11,000 years ago. Evidence needed for such a quantitative
approach may be present in the fresh-
transition of forest types may have
been recorded. Many of the offshore
swamps and bogs should have been
relatively free of the local edaphic and
water autochthonous peats that are sub-
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An interesting problem of plant
physiology is raised by the finding that
plants high on the salt-marsh have ratics of stable carbon isotopes similar to
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short length of time that they are submerged. The measurements that were
made indicate that 6C™
is a useful
means of distinguishing between an-
rei B0S
RUBIN (1962)
paleoclimatology.
those of marine plants, in spite of the
THOUSANDS OF YEARS AGO
6
physiographic variables that complicate
many upland sites of organic deposition, such as the pollen rain from the
windward montane forests of the Appalachian Highlands. Accordingly, further work on the offshore peat deposits
may be highly rewarding for studies of
I
Fig. 6. Depths of radiocarbon-dated samples of peat (closed circles) and shells (open
circles) whose positions are given by Table 1 and in Figs. 1 and 2. Dates for V
and AZ are based only upon their pollen contents. The curved line shows the position of sea level 4000 to 11,000 years ago according to the ages and present depths
of oyster shells and of the salt-marsh peat within sample RL1. At the left, the
wide straight lines indicate the position of sea level during the past 3800 years according to radiocarbon dates of Barnstable galt marsh (/5).
cient salt-marsh and freshwater peats.
K. O. EMERY
Woods Hole Oceanographic Institution,
Woods Hole, Massachusetts
R, L. WIGLEY
U.S. Bureau of Commercial Fisheries,
Biological Laboratory, Woods Hole
ALEXANDRA 8S. BARTLETT
Department of Biology and Botanical
Museum, Harvard University,
Cambridge, Massachusetts
MEYER RUBIN
Radiocarbon Laboratory,
U.S. Geological Survey,
Washington, D.C.
E. S. BARGHOORN
Department of Biology and
Botanical Museum, Harvard University
References and Notes
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Fig. 7. Schematic diagram of the relation of freshwater ponds to other environments of New England. Areas marked PONDS are characterized by freshwater peats,
LAGOONSbysalt-marsh peats and oyster shells; OCEAN by marine sands and silts, _
and GLACIERS bytill and outwash.
1306
wh
20
P
oman
Arsbok 51, No. 557, 1 (1957).
. H. F. Nelson and E. E. Bray, Program
Geol. Soc. Amer, (annual meeting, San Francisco, 1966), p. 150.
6. E. McFarlan, Jr., Bull. Geol. Soc. Amer. 72,
129 (1961).
7. D. M. Churchill, J. Roy. Soe. W. Australia
42, 53 (1959).
8 . T. van der Hammen, Leidse Geol. Mededel.
z9, 125 (1963).
9 . G. H. Keller and A. F. Richards, J. Sed.
Petrol. 37, 202 (1967).
10. H. Niino, Tokyo Univ. Fisheries, personal
communication (1966).
V1, J. R. L. Allen, Marine Geol. 1, 289 (1964).
12. K, O. Emery, R. L. Wigley, M. Rubin,
Limnol. Oceanogr. 10, R97 (1965).
13. J. M. Zeigler, S. D. Tuttle, H. J. Tasha,
G, S. Giese, Bull. Geol. Soc. Amer. 75, 705
(1964),
14. W. M. Sackett, Marine Geol. 2, 173 (1964).
15. A. C. Redfield and M. Rubin, Proc. Nat.
Acad. Sci. U.S. 48, 1728 (1962).
16. A. C. Redfield, Science 157, 687 (1967); W. S.
Newman and G, A, Rusnak, ibid. 148, 1464
(1965).
17. F. P. Shepard, Essays in Marine Geology
(Hancock Foundation, Univ. of Southern
California, Los Angeles, 1963), p. 1; K. O.
Emery and L. E. Garrison, Science 157, 684
(1967).
18. C. A, Kaye, U.S. Geol. Surv. Prof. Paper
SO0I-C (1964), p. 134.
9. J. P. Schafer and J. H. Hartshorn, in The
Quaternary of the United States, H. E. Wright
and D. G. Frey, Eds. (Princeton Univ. Press,
Princeton, N.J.. 1965), p. 113.
ta
+25 (======rs = sie
1. J. W. Stather, Quart. J. Geol. Sec. London
68, 324 (1912).
H. J, Veenstra, Marine Geol. 3, 245 (1965).
K.
Andrée,
Geolegie
des
Meeresbodens
(Gebriider Borntraeger, Leipzig, 1920).
. G, Lundqvist, Sveriges Geol, Undersékn,
—_
0
THOUSANDS OF YEARS AGO
SCIENCE, VOL. 158