QUATERNARY PALYNOLOGY

- the quantitative analysis of pollen, spores and related microfossils in sediments of Quaternary age (the last 2.5 million years). Quaternary Palynology relies on precise dating for correlation among stratigraphic sequences, and for reconstructing rates of environmental change. For the late-Quaternary (the last 50,000 years), time control is based primarily upon radiocarbon dating. The Quaternary spans much of the time of the development of humans. Particularly during the late Quaternary, the influence of environmental change on humans, and the influence of humans on the environment are important themes of Quaternary Palynology.


The term 'palynology' was suggested by Hyde & Williams from the Greek "to strew or sprinkle" because by 1944 the discipline had come to include microfossils other than pollen, and because it had developed beyond mere identification of pollen and determination of its stratigraphic range.

As so defined, "palynology" was first practiced in the 1910's by Lenart Von Post, who systematically enumerated pollen and spores in samples of bog sediment and calculated the percentages of the major pollen types as an index of past vegetation. Even though fossil pollen and spores had been recognized pre-Quaternary by Reinsch in 1881. During the first half of the twentieth Von Post provided a palynological basis for the Blytt-Syrnander climatic sequence, which had been based on peat stratigraphy, and he helped to provide chronological control for this sequence by analyzing pollen in the varves of the Baltic Basin. After World War Two, Quaternary Palynology developed rapidly in the New World through the application of the technique to lake sediments, made possible by the development of piston corers by Livingston and others. The application of palynology to non-forested regions in the New World lead to a re-evaluation of the basic concepts of palynology such as the pollen sum for percentages. This lead, in turn, to the "absolute" measures of pollen abundance (concentration and "influx"). The comparison of contemporary vegetation with the modern pollen rain ("surface sample studies") has been facilitated by the relatively un-disturbed nature of North American vegetation. More recently, computer techniques have facilitated the quantitative interpretation of Quaternary sequences and have permitted the rapid transmission and graphical display of palynological data.

Compared to stratigraphic palynology, Quaternary palynology is more quantitative, and unlike stratigraphic palynology, it assumes that the pollen and spores investigated are produced by living taxa (Families, Genera, or Species). Routinely, 300 to 500 pollen grains are counted per sample, and these abundances are formally compared to vegetation and environmental properties through "surface sample studies." The assumption of "modernity" is fundamental to Quaternary palynology, because it uses the ecological tolerances of the recognized taxa to interpret past precipitation and temperature and other environmental parameters.

The reliance on the ecological tolerances is justified by indications of long-term stability in the fossil record, and by the "stasis" (vs. gradualistic) model of the tempo of evolution. Most paleontologists would probably agree that on a millennial time scale (i.e., the Holocene) the assumption of "modernity" is justified -- on the genus level of routine pollen identification. However, the assumption may have lead to a level of "complacency" that has failed to identify species-level plant extinctions despite the major extirpation of grazing herbivores in the New World 10,000 years ago.


References:
  • Reinsch, P. 1881
    Neue Untersuchungen über die mikrostruktur der steinkohle des carbon der Dyas and Trias. Leipzig. 124 pp, 14 pl.
  • Von Post, L. 1917
    Om skogsträdpollen i sydsvenska torfmosselagerföljder. Geologiska Foreningens i Stockholm Forhandlingar 38: 384-390
  • Wright H. E. 1980.
    Cores of soft lake sdeiments. Boreas 9: 107-114.
  • Eldridge, N., and Gould, S. J., 1972
    Punctuated Equilibria: An Alternative to Phyletic Gradualism, in Schopf, T. M., ed., Models in Paleobiology: San Francisco, Freeman, Cooper, & Co., p. 82-115; 250 pp.
  • Wright H. E. 1967.
    The use of surface samples in Quaternary pollen analysis. Review Palaeobotany Palynology 2: 321-330.

    AASP References:
  • V.M. Bryant & R.G. Holloway (1985) Pollen records of Late-Quaternary North American Sediments.
  • AASP Foundation Contributions Series 13
  • Faegri & Iversen (1989); Moore, Webb & Collinson (1991) etc.

  • Owen Davis 12/99