Table 2. Species composition of recent and glacial samples for each core (expressed as percentages). Since only eight species are reported from
the total flora, the percentage values do not equal 100. Abbreviations: R, recent; G, glacial; x represents values that are less than 1 but
greater than 0.5 percent.
A153-146
x
AlS6-4
A1‘S6-5
A164-59
x
Xx
A167-13
A167-14
A179-13
A1T79-17
A180-9
A180-16
A180-32
G
R
AI180-48
R
1
5
9
6
1
x
x
2
x
1
3
5
x
3
2
2
Helico-
x
3
4
Rhabdo-
sphaera
carteri
G
x
x
18
x
lithus
leptoporus
G
G
R
2
1
x
1
x
1
x
7
1
1
5
10
10
9
x
6
5
15
1
2
1
2
3
x
10
4
x
4
3
x
1
2
3
1
1
2
1
x
x
2
RS5-36
R5-54
R5-57
R10-2
SP8-4
SP9-3
SP9-4
SP10-1
V16-200
x
x
4
1
1
30
6
1
1
2
0.5
1
5
3
27
2
2
3
8
16
8
14
6
6
11
1
9
5
6
2
3
4
1
1
0.5
5
8
25
13
18
8
plotted on a map and each boundary
is given the present value of the maximum temperature (isotherm), it should
be possible to draw a paleoisotherm map
for the glacial period. Having laid out
the temperature lines for the species
and interpolating between overlapping
ranges, I found it possible to draw
a tentative paleoisotherm map (Fig.
3). Although insufficient core coverage
makes any fine adjustment of these
lines impossible (a gap remains in the
northwest portion of the Atlantic), two
lines, the 14° and the 22°C isotherms,
are established on the basis of a number of overlapping species. The addition of more core material and the
mapping of other species boundaries
should result in a paleoisotherm map
that will be an accurate representation of the average temperature of surface water of the glacial North Atlantic.
In seven species the amountoflatitudinal shift between glacial and recent
is greatest along the eastern side of
the Atlantic. In the three species with
subtropical to transitional ranges it is
a factor of 2 to 3. This distributional
difference is presumably the result of
the main current system in existence
today and in the Wisconsin. At present
the distribution of R. stylifera, H. carteri, U. tenuis, and S. pulchra is en-
compassed by the northern boundary
of the subtropical gyral (Gulf Stream).
8 DECEMBER 1967
1
4
1
6
1
3
R
0.5
x
G
2
3
1
1
1
R
G
1
1
4
3
x
2
3
4
x
2
2
2.5
x
J
1
2
1
2
1
2
1
x
x
x
2
x
4
x
2
1
1
1
7
6
3
3
4
x
1
2
7
11
2
1
8
6
1
1
2
3
9
4
I
2
x
1
1
4
4
1
9
2
5
1
x
2
2
3
1
2
4
3
I
14
1
6
x
This boundary rises from approximately 40°N latitude off North America to
over 55°N latitude off Europe. This is
also true for other subtropical coccolith species not included in this report. In the mid-Wisconsin the line of
species presenceis relatively horizontal,
running roughly parallel to the 30°
latitude line with a slight southern turn
along the eastern edge of the Atlantic
(Fig. 3).
Admittedly the core density is some-
what low; nevertheless, the core coverage is sufficient to allow no more than
a 5° fluctuation in latitude without a
major change in azimuth of this line
since it is bracketed by cores. If one
compares data (Figs.
sphaera
mirabilis
G
2
4
Um bilico-
R
J
x
2.5
G
sphaera
tenuis
]
2
13
Umbello-
sphaera
irregularis
2
1
J
A180-56
A180-72
Umbeilo-
sphaera
pulchra
R
6
2
2
Syraco-
sphaera
stylifera
1 and 2), it is
possible to say that the northern border
of the subtropical gyral during midWisconsin time flowed along or near
the 33° latitude line.
From this first report, based on information gained from modern species
1
x
1
1
x
2
22
greatest shift occurring in the eastern
Atlantic; (ii) that it may be possible
to erect paleoisotherm maps of surface
water with the use of population boundaries of Coccolithophoridae species of
known temperature range as isotherms,
particularly if greater core coverage can
be combined with data on additional
species; and (iii) that the northern
boundary of the subtropical gyral,
from a present position of approximately 40° latitude off North America to
over 55° latitude off Europe, was displaced to a position extending from ap-
proximately 30°N latitude off North
America to
approximately
38°
off
Europe.
ANDREW MCINTYRE
Lamont Geological Observatory,
Palisades, New York
References and Notes
1. D. B, Ericson, M. Ewing, G. Wollin, B. C,
tion: (i) That the maximum cooling in
the mid-Wisconsin resulted in a south-
Heezen, Geol. Soc. Amer. 72(2) 193 (1961).
. C. Emiliani, J. Geol, 63, 538 (1955).
G. A. Riley, Limnol. Oceanogr. 2, 252 (1957);
E. M. Hutburt, ibid. 7, 307 (1962).
A. McIntyre and A. W. H. Bé, Deep-Sea Res.,
in press.
H. G. Marshall, Limnol. Oceanogr. 11, 432
(1966).
A. W. H. Bé and A. MelIntyre, Spec. Paper
Geol, Soc. Amer, 82, 8 {abstr.) (1964); N.
Watabe and K. M. Wilbur, Limnol. Oceanogr.
11, 567 (1966),
8. I thank A. W. H. Bé for helpful discussion
and J. Imbrie, W. Broecker, A. Gordon, and
C. Drake for criticism of the manuscript. Supported by National Science Foundation grant
GP 4768. Lamont Geological Observatery con-
of approximately 15° latitude, with the
6 September 1967
of Coccolithophoridae, it appears that
coccoliths can be used for paleoecologic
studies and that the application of these
studies to the problem in this report
has led to the following conclusions
about the effect of cooling on the North
Atlantic during the Wisconsin glacia-
ward shift of planktonic populations
wh
R
Cyclococco-
w
Coccolithus
pelagicus
na
Core
No.
tribution No. 1131.
1317