Holocene/Recent The Holocene is the later of the two epochs of the Quaternary Period, the earlier being the Pleistocene. The Recent Series was proposed for post-glacial deposits by Charles Lyell in 1833, but the definition of the base of the series is vague at best. It was suggested that deposits formed since the arrival of man should be designated as Recent. The term is synonymous with Holocene, which was the term agreed for the post-Pleistocene by the International Geological Congress of 1885, but the means by which the base of this division could be recognized were still far from certain.
After exhaustive discussion relating to glacial and post-glacial successions in many parts of the world, general agreement now favours the selection of criteria that can be recognized without reference to specific local conditions. There are several, but nevertheless common consent is given to the selection of an age in years. This most recent epoch is held to date from 10 000 years ago to the present moment. It is a span of time in which climatic fluctuation has continued and the natural environment has come under increasing pressure from mankind.
The general warming of world climate has led to the diminution of ice caps and glaciers, and as a consequence sea level has been rising. This, the Flandrian transgression, began to take effect about the beginning of the Holocene. During this time, levels might have risen as much as 170 m. The Flandrian transgression is thought to have reached its climax about 6700 years ago with sea level a few metres above the present.
Climatic changes are reflected in the preserved record of plant species present in the deposits, and pollens contribute substantially to this. In Britain, the pollens indicate cooling and increased precipitation after the so-called climatic optimum around 5000 BP. Botany, too, helps to establish a quantitative means of dating Holocene and Recent events; the discipline is known as dendrochronology, or tree-ring analysis. The technique involves the counting and measurement of tree-ring thicknesses in ancient timbers. They reflect the growing (i.e. climatic) conditions prevailing year by year as the trees grew, and they tend to show very similar patterns over spans of time even in different species. European dendrochronology now goes back over 11 000 years before the present, and research in Germany has corroborated tree-ring dates with radiocarbon and stable isotope analyses.
In Scandinavia and North America, sediments from several recent and existing lakes receive an annual layer (of sediment) with the spring thaw. It can be shown that these layers, rhythmites (or varves), have been accumulating for a long time, and provide a kind of calendar dating back throughout the Holocene.
A chronology unique to the Quaternary, and especially important in the Holocene, concerns the succession of stone artefact cultures. Stone tools, commonly of flint, from the Holocene date back to the Mesolithic (Maglemosian– Tardenoisian) in Europe. After the Mesolithic, and beginning about 8000 years ago, came the Neolithic, during which the rise in sea level came to an end. Human cultures now spread from the subtropical regions into the steppes and temperate climes where the grasses could be selected to provide abundant food. Cereal collecting soon gave way to cereal cultivation and the domestication of sheep and cattle. Pastoral nomads evolved their special niches in both the Old World and the New by about 5000 years ago, and the Bronze Age dawned in the Near East. Migration increased in pace and the world human population was in the realm of tens of millions.
The process of change continues and we are at some pains to understand the mechanisms by which it proceeds. The future comfort and prosperity of the human race depends to large measure upon ability to contend with inevitable natural changes—which may be drastic—and also to ensure that human activities do not further detract from the planet's amenities. The Holocene epoch is a short one, so far: the changes it has seen have been minor by geological standards; no catastrophic rare global event has occurred so far. There are many pitfalls in the process of prediction. UNESCO and other agencies are establishing work in natural disaster reduction and in monitoring the effects of global geological and biological change. Understanding the past may be of some assistance in understanding the present. Understanding what may lie ahead is fraught with even greater difficulties.
D. L. Dineley
Bibliography
Calder, N. (1984) Timescale: an atlas of the fourth dimension. Chatto and Windus, London.
Taylor, J. (1978) Present day. In McKerrow, W. S. (ed.) The ecology of fossils. Duckworth, London.
