An insect assemblage of early Flandrian age from Lea Marston, Warwickshire, and its bearing on the contemporary climate and ecology

Abstract

An extensive insect fauna is described from an organic deposit occurring in a gravel pit at Lea Marston, Warwickshire, England. This organic deposit was lying beneath approximately 2.5 m of alluvial clay and directly above gravels which had provided organic material 14C dated at 11,700 ± 200 yr BP. The insect fauna was indicative of a temperate oceanic climate similar to that found today in southern England or south Sweden and suggested the presence of deciduous woodland. The six radiocarbon dates, however, agreed in giving the deposit an age of around 9500 yr BP which is earlier than the arrival of the principal broad-leaved trees. The pollen assemblage was consistent with the radiocarbon dates in showing, in addition to herbaceous pollen, only the presence of Betula, Salix, and small amounts of Pinus. As the insect faunas known from midland Britain at the close of the Devensian period, barely 500 yr before, are aretic in aspect and entirely devoid of thermophilous species a very rapid climatic amelioration is postulated which permitted the immigration of the very mobile insect fauna well in advance of the more slowly migrating trees.