OUTLINE OF CLIMATIC FLUCTUATION SINCE THE LAST INTERGLACIAL AGE*

Richard Foster Flint Department of Geology, Yale University, New Haven, Conn.

Friedrich Brandtner United States Geological Survey, Washington, D.C.

The number and dates of the principal fluctuations of climate since the last major interglacial have been an object of considerable interest during recent years. The important curves published, beginning in 1955, by Emiliani (1958 and titles cited therein), were a pioneer attempt at a graphic representa- tion of climatic changes based on isotopic temperature measurement of sea-floor sediments, with at least partial time calibration. Later several curves based on data from continental stations were constructed by various investigators, and some of them were published. Some are CI4-time calibrated, to a first approximation, through a time range of more than 60,000 years.

Using published and unpublished curves, we here compare (FIGURE 1) data from continental stations in Denmark, the Netherlands, Lower Austria, south- eastern California, the Great Lakes-St. Lawrence region, and equatorial Colom- bia. We have used a common scale for time and a scale for temperature that is as nearly uniform as the data permit.

The curves from Denmark and the Netherlands are those published by Andersen, de Vries, and Zagwijn (1960). They are based on pollen analyses, and their far ends, in the vicinity of 70,000 years B.P., are thought by those authors to belong to the end of the Eem Interglacial.

The curve for Lower Austria is based chiefly on a sequence of fossiliferous loess layers and intervening ancient soils. The near end of the curve is based on pollen-analyzed lake sediments and peat layers. Although a large number of exposed sections is involved, the sections agree in showing similar physical and chemical characteristics. Relevant publications include Brandtner (1950, 1954, 1956, 1959) and Fink (1954, 1956). The Fellabrunn soil complex (the Stillfried Complex of Fink, 1954) is equivalent to the time unit known as the Gottweig Interstadial. A critical evaluation of the CI4 dates obtained by Hessel de Vries from this complex will be published by Brandtner in Eiszeitalter und Gegenwart in 1961.

The curve for southeastern California was constructed from data published by Flint and Gale (1958) and Roosma (1958). The segments labeled Deep Luke represent sediments deposited in water that was deep, although saturated, most of the time, with carbonate compounds in solution. The segments labeled Desiccation represent evaporites. The amplitude of fluctuation of temperature and/or precipitation is not known from the physical evidence. The rectilinear form of the graph reflects abrupt changes in type of sediment, not rate of change of temperature and/or precipitation. If rates of change were known, the graphic slopes would be curves rather than rectilinear in form.

* Parts of this article, which is published by permission of the Geological Survey, Washing- ton, D.C., have appeared elsewhere previously (Flint and Brandtner, 1961).

457

I Years B.P x 1000-0 I0 2 0 3g 49 5.0 SQ 7.0 1

FIGURE 1. Climatic variations in middle north latitudes and at an equatorial station, within the last 70,000 years, inferred from terrestrial data. Circles show positions of C14-dated samples.

Denmark and Netherlands curves (reproduced directly from Anderson, de Vries, and Zagwijn, 1960) are based on pollen data; continuous lines indicate continuous pollen stratig- raphy.

Lower Austria curve, composite for a region, is based on a stratigraphic sequence of loess sheets and soils. The C14 date prefixed H is from the Heidelberg laboratory; all the others are from the Groningen laboratory. Localities: F , Fellabrunn; P, Pollau (= Pavlov); W , Unter Wisternitz (= Dolni VEstonice); WZ2/5 or 4, Willendorf site 11, layer 5 or 4; S, Senf-

Temperature calibration differs somewhat between the two curves.

tenberg; R, Roggendorf.

on Dollen, as indicated. Searles Lake curves are based on physical/chemical characteristics of lake sediments and

Pollen curve is from Roosma (1958). Great 'Lakes-St. Lawrence curve is composite, having been compiled from a variety of

sources (notably de Vries and Dreimanis, 1960) within a rather wide region. The two pre- classical-Wisconsin glacial intervals are based on glacial drift; the nonglacial segments on peat and gyttja.

Colombia curve (from van der Hammen and Gonzalez, 1960, p. 305) is based on pollen data.

458

Flint & Brandtner: Climatic Fluctuation 459 This is evident from the related curve constructed by Roosma from pollen contained in the sediments.

Fluctuations of climate antedating the youngest deep-lake phase and ex- tending back considerably beyond the 70,000-year limit shown in FIGURE 1 are indicated by the stratigraphy (Smith, 1958). Although we accept the fluctuations, we have omitted them from our curve because the available C14 dates seem inadequate for control of their positions.

Although we have not included the curve developed from Lake Bonneville sediments by Eardley and Gvosdetsky (1960) because it is not controlled by finite dates, it shows considerable agreement with the Searles Lake curve.

The Great Lakes-St. Lawrence curve has been drawn from various sources. Its far part, antedating 24,000 years B.P., is based on data from de Vries and Dreimanis (1960), Dreimanis (1960, p. 112), and Terasmae (1957). The near part is based chiefly on data assembled by Flint and Rubin (1955) and Flint (1956), from sources cited in those publications. The data do not permit direct temperature calibration, which is relative and suggested only.

The curve from Colombia, the work of van der Hammen and Gonzalez (1960), is based on the pollen record of lake sediments from an altitude of 8500 feet a t 4" 30' N Lat. With the concurrence of van der Hammen, the version of the curve shown in FIGURE 1 was obtained by fitting that part of the curve correlated by van der Hammen and Gonzdez with the Wiirm Glacial plus the Holocene with the 70,000-year length of the other curves in FIGURE 1. The agreement among major cold and warm intervals is good, as those authors noted (op. cit., p. 307).

As a group, the six curves show good agreement as to their major features, all that can be expected because temperature calibration is not uniform. Probably the Lower Austria curve represents the best over-all documentation, whereas the Colombia curve, although not time calibrated, is the most com- pletely controlled stratigraphically. The similarities among the curves indicate that in several middle-latitude areas of the northern hemisphere and in equa- torial South America, climatic fluctuation during the last 70,000 years has been broadly similar, consisting apparently of three principal cold intervals, all younger than the last major interglacial time.

As a group the curves also agree broadly with those developed by Emiliani (1958) for surface-seawater temperature in low and middle latitudes.

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