The Uses of Pollen Analysis


Copyright © 1996 by Sean Mewhinney (df736@freenet.carleton.ca).


In Worlds in Collision, Velikovsky stated his theory that the ice age of Europe and America ended in a displacement of the terrestrial poles:

"The glacial sheet was a polar cover; the ice ages terminated with catastrophic suddenness; regions of mild climate moved instantly into the polar circle; the ice sheet in America and Europe started to melt; great quantities of vapor rising from the surface of the oceans caused increased precipitation and the formation of a new ice cover." 1

He believed that this shift had taken place quite recently:

"It is probable that twenty-seven centuries ago, or perhaps thirty-five, the present North Pole was at Baffin Land [sic] or close to the Boothia Felix Peninsula of the American mainland." 2

(Of course, the present north pole has always been at the present north pole. But you know what he means.) The former date would fit with the date of his supposed Mars catastrophes; the latter with his date of the Exodus and his Venus catastrophes. This theory was restated five years later in Earth in Upheaval, in Chapter IX, "Axis Shifted." (esp. pp. 137 ff., "A Working Hypothesis")

As its title suggests, the next chapter, "Thirty-five Centuries Ago," is intended to demonstrate that the last glaciation could have ended as late as 3500 years ago, or even later. First Velikovsky criticizes the Swedish varve chronology and the radiocarbon dating method, predicting that "more and more puzzling' results of radiocarbon tests will compel a full-scale revision of the dating of the glacial periods." 3 Then he enumerates a series of estimates made of the length of time needed to complete various geological processes since the ice retreated to cut the Niagara River gorge, to build the Bear River delta, for the salt to accumulate in various lakes arriving in each case at a figure between 2500 and 4000 years.

Much space in the next chapter, "Klimasturz," is devoted to evidence for climatic changes which supposedly support Velikovsky's claim of global catastrophes in the 15th and 8th centuries B.C. Most of this evidence is either deduced from pollen analysis or dated by reference to the sequence of botanical-climatic periods introduced by Axel Blytt and championed by Rutger Sernander.

This scheme was based on work in the peat bogs of northern Europe. In some of the bogs he investigated, Blytt found alternating layers of peat and tree stumps. From this fact, he posited a succession of alternately wet and dry periods, the wet periods corresponding to the layers of peat, the dry periods to the layers of stumps. Other plant remains imbedded in the peat fruits and seeds, leaves, pieces of wood or pollen grains, in vast numbers are often found far from the present habitats of those plants. Past climatic conditions can be inferred from the temperature and moisture requirements of each genus of plants, as well as differences in the composition of the peat itself at different levels.

The term klimasturz, coined by Sernander, means literally a "plunge" in climate and indicates a sharp drop in temperature, accompanied by an increase in precipitation, which he believed had taken place at the end of a period he called the Subboreal.

" The deterioration of the climate must have been catastrophic in character,' wrote Sernander To the period of the greatest change he gave the name Fimbul-Winter, borrowing the term from the northern epic, the Edda. In this epic Fimbul-Winter is a designation for a snowfall that continued through winter and summer alike, uninterrupted for years." 4

Could this have been the "Fimbul-winter" of Worlds in Collision, in which:

"the earth was removed to an orbit farther from the sun; the polar regions were displaced; oceans and seas evaporated and the vapors precipitated as snow on new polar regions and in the higher latitudes in a long Fimbul-winter and formed new ice sheets." 5

Velikovsky strongly implied that it was. In fact, he declared that Sernander's "researches, unknown to me when I wrote Worlds in Collision, coincide completely with my conclusions and their dating." 6 But do they?

In northern Europe and North America, the glacial period was characterized by a sparse arctic flora of grassy herbs, shrubs, mosses, lichens, and sedges. As the ice sheets began a rapid retreat, this vegetation was replaced by successive waves of trees. Dwarf willow and birch, followed by spruce, pine, alder, elm, and oak, invaded the northern temperate latitudes. The border between tundra and forest gradually moved northward, reaching a line hundreds of kilometers north of its present position. The tree line climbed up the mountainsides, 300 meters higher than trees can now grow. It is estimated that at their peak, during the Atlantic period, temperatures were 2½° C warmer than now. This is about one fifth of the temperature difference between the late glacial maximum and the present for these latitudes. 7 (The average global difference was only 5° C. 8)

Since that time, temperatures have fallen, and the forest has retreated. Sernander differed from earlier investigators in believing that most of this reversal occurred abruptly at the close of the Subboreal period: "It happened by and large in a few centuries." 9

Among the evidence that most strongly impressed Sernander was the work of C. A. Weber in the bogs of northern Germany. In one bog after another, Weber found what he called the "boundary horizon," an abrupt transition between two different grades of peat, which he dated to about 500 or 600 B.C. Below this level, the peat was darker, more humified, and it burned better than the peat above it. A change in the proportions of different plant species composing the peat indicates a change toward wetter conditions and accelerated peat growth above this level.

The original Blytt-Sernander scheme distinguished four post-glacial climatic periods: in descending order, the Boreal (dry), Atlantic (warm and wet), Subboreal (warm and dry), and Subatlantic (cool and wet). Later investigators added a Preboreal period between the Boreal and the last glacial stage, the Younger Dryas. (See Fig. 1.) The Subboreal corresponds roughly to the Bronze Age of northern Europe, and the Subatlantic to the Iron Age. Sernander's klimasturz marks the transition from Subboreal to Subatlantic.

For Sernander to compare the klimasturz to the Fimbul winter of the myths of his own Nordic peoples was natural enough, but that does not imply that he considered it at all comparable to the Ice Age in severity, or that he confused these two periods. It was clear to Sernander that the klimasturz was separated from the end of the Ice Age by thousands of years, spanning three broad climatic stages.

Velikovsky simply ignores this. How is is possible for the human mind to embrace two such mutually contradictory ideas at one and the same time? He was in a state of mind where he could see only confirmation of his own ideas even in a direct contradiction.

Today, with a much clearer and more detailed picture built up from subsequent research, we know that there have been a number of significant climatic oscillations in post-glacial times. In the 1930's, Erik Granlund's work on the bogs of southern Sweden showed that Weber's "boundary horizon" was not unique. He found five such layers, recognizable across a wide area, which he called "recurrence surfaces." He dated them approximately 2300 B.C., 1200 B.C., 500 B.C., 400 A.D., and 1200 A.D. Several years later, Tage Nilsson extended the list to nine, the earliest dating from approximately 3500 B.C. 10 Evidently the climate of Europe has alternated many times between markedly drier and wetter conditions.

A great aid in reconstructing past climate has been the development of pollen statistics, introduced by Sernander's most prominent pupil, Lennart von Post. Unlike macrofossil plant remains, which depend on chance finds, pollen indicates more than the mere presence or absence of a particular plant at some time in the past. Pollen grains are present in vast numbers, even in a tiny sample of peat or mud, and they are virtually indestructible. Because pollen can travel a great distance on the wind, the pollen falling on a given site reflects the vegetation not only at that specific spot, but from the general vicinity. So with an economy of effort, one can establish the relative importance of each type in the plant community by counting pollen grains, and with as fine a time resolution as one would like. The results are usually plotted in a diagram.

Comparing pollen diagrams from the length and breadth of Europe, and from further afield, von Post found that in spite of many local differences, they show the same basic pattern in the course of their post-glacial development. The flora can be divided into two components.

One group of plant species predominates at the outset, declines in importance in the middle phase, and then recovers in recent times, though not becoming as dominant as before. Von Post calls these elements "terminocratic". The other group, which consists of warmth-loving forms and peaks in the middle phase, he calls "mediocratic". Although the species which comprise the terminal and middle phases in each region are different, they all exhibit this pattern of "revertence". Von Post called this the law of regional parallelism. 11

Correlations with archeological remains, uplifted Baltic shorelines, and post-glacial varves in Sweden showed that temperatures had begun to fall at least 4,000 years ago. Superimposed on this broad outline were numerous oscillations between "Fimbul winters" and periods of milder climate, the fine details of which would become clearer with further research.

Von Post proposed his threefold division of post-glacial time as an alternative of more general applicability than the Blytt-Sernander scheme of alternating wet and dry periods, modeled on the example of northwestern Europe. However, the Blytt-Sernander system had by then become too entrenched, and it is von Post's scheme, not the other, which has been consigned to the history of science.

According to Velikovsky, the north pole was violently wrenched a distance of 20 degrees in an arc 90° west of the Greenwich meridian. The climatic histories of Canada and Siberia, then, should be distinctly antiparallel. This is not what we find.

The boundary between forest and tundra in the northern hemisphere is determined mainly by temperature. This boundary has repeatedly oscillated north or south in response to climatic changes during the last several thousand years. These displacements are not everywhere of the same magnitude. But broadly speaking, throughout the northern latitudes of Europe, North America, and Siberia, the fluctuations are in phase, that is, the change is in the same direction in the same period.

  11,000 B.P.  
YOUNGER DRYAS   Late Ice Age
  10,000 B.P.  
PREBOREAL    
  9,000 B.P.  
BOREAL   Dry
  8,000 B.P.  
ATLANTIC   Warm and Wet
  5,000 B.P.  
SUBBOREAL   Warm and Dry
  2,500 B.P.  
SUBATLANTIC   Cool and Wet
  Present  

Fig. 1

Modified Blytt-Sernander scheme of climatic periods, as given by J. Mangerud et al., in Boreas Vol. 3 (1974), p. 119. Approximate dates of stage boundaries are given in uncorrected radiocarbon years before 1950.


Notes

1. Immanuel Velikovsky, Worlds in Collision, p. 325.

2. Ibid., p. 326.

3. Velikovsky, Earth in Upheaval, p. 159. This has not happened. On the contrary, radiocarbon dates confirm the dates arrived at by other methods for the end of the last glaciation, and no such drastic reduction is possible.

4. Ibid., p. 174.

5. Worlds in Collision, p. 120.

6. Velikovsky, address given at Princeton University in 1953, appended to Earth in Upheaval, p. 285.

7. Rhodes W. Fairbridge, "Climatic Variation, Historical Record," in John E. Oliver and Rhodes W. Fairbridge, eds., The Encyclopedia of Climatology (N.Y., Van Nostrand Reinhold, 1987), p. 319; H. Godwin, History of the British Flora, (Cambridge Univ. Press, 1956), p. 28.

8. W. Lawrence Gates, "Modelling the Ice-Age Climate," Science, March 19, 1976, p. 1141; Syukuro Manabe and Douglas G. Hahn, "Simulation of the Tropical Climate of an Ice Age," Journal of Geophysical Research, Vol. 82, no. 27 (Sept. 20, 1977), p. 3910.

9. Rutger Sernander, "Klimaverschlecterung, Postglaziale," in Max Ebert's Reallexikon der Vorgeschichte, Vol. 7 (Berlin, de Gruyter, 1926), p. 7.

10. H. Godwin, op. cit., p. 34.

11. Lennart von Post, "The Prospect for Pollen Analysis in the Study of the Earth's Climatic History," New Phytologist, Vol. 45 (1946), pp. 198, 203.


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Last modified by pib on October 28, 2003.