Overview

Great Britain shows a rich variety of landscape with landforms and rocks of all geological ages being represented. The oldest rocks are found at the surface in north west Scotland and are more than half as old as the planet. They are thought to underlie much of Great Britain. The youngest rocks are found in south east England.

The bedrock consists of layers formed over vast periods of time. These were laid down as the climate changed, the landmasses moved due to plate tectonics, and the land and sea levels rose or fell. From time to time horizontal forces caused the rock to undergo deformation, folding the layers of rock to form mountains which have since been eroded and overlain with other layers. To further complicate the geology, the land has also been subject to periods of earthquakes and volcanic activity.

Soils and fragmental material deposited by glaciers overlie this bedrock geology in most parts. The bedrock of Holt and Little Witley consists of sandstone and mudstone laid down during the Permian and Triassic periods in excess of 160 million years ago at a time when the UK was positioned nearer the equator and the flora, and fauna in particular, would appear to be completely alien to the modern observer. .

The landscapes of Western Europe, and the plant and animal communities that live there, have passed through a series of profound and often rapid changes during the last two million years, during the late Pliocene and the Pleistocene periods. Although there were long intervals of temperate climate, similar to or even warmer than that of today, first during the later Pliocene and then during the Pleistocene interglacials, these alternated with a series of increasingly cold and then glacial periods. At the height of the Pleistocene glaciations, ice-sheets spread across much of Europe, reaching their greatest extent and thickness in the maritime areas of northwestern Europe.

Traditionally each of the glacial phases and interspersed interglacial periods was given a name, based on a ‘type’ site, where features typical of the period in question were first described. The Cromerian Interglacial followed an early Pleistocene glacial phase. The Anglian Glaciation, Hoxnian Interglacial, Wolstonian Glaciation, Ipswichian Interglacial and Devensian Glaciation followed. The Devensian Glaciation gave way to the present Post-glacial period. There is no agreement between authors as to the start and finish dates for the various glacial and interglacial periods. The older the period the less agreement there is. Dates quoted in the following chapters are only one proposed set of timings.

More recently the various Pleistocene periods has been descibed in terms of Oxygen Isotopes Stages (OIS). To ascertain these a mass spectrometer is used to measure the ratio of the number of oxygen isotopes within a sample, the ratio of one to another indicating which OIS stage is represented. There are three stable isotopes of oxygen, of which oxygen-16 is the most abundant; and oxygen-17 and oxygen-18 are much rarer. Of the two minority isotopes, oxygen-18 is the more abundant, but even so its ratio with respect to oxygen-16 is only in the range 0.0019–0.0021 in natural materials. Today, oxygen isotope stratigraphy has burgeoned into one of the most widely used analytical techniques in the palaeontological arsenal. To date researchers have identified more than 100 oxygen isotope 'stages', a series of more than 20 of which are glacial–interglacial stages covering the Pleistocene ice ages. The precise correlation between the traditional Ice Age periods and the OIS periods is still subject to some debate.

Sometimes a secondary advance of glaciers took place within a glacial period. These climatic episodes are referred to as stadials. The glacial periods were often interspersed with ‘brief’ periods of ameliorated climate. If time, and/or the degree of amelioration only allowed the development of a community that has its modern counterpart in the boreal deciduous (birch), or boreal coniferous (pine/spruce) forest before deterioration sets in then the interval is referred to as an interstadial. The development of temperate summer deciduous forests characterises the interglacial periods.

The makeup of the fauna and flora of each period was unique and often surprising when we consider our present, somewhat impoverished, natural surroundings. At various times in England, animals such lions, hyaenas and Cave Bears preyed upon elephants, mammoths, rhinos, giant deer and even hippopotami.

Although few animal remains have been recovered from Holt or Little Witley, based on finds from elsewhere in the UK, one can speculate as to the species and habitats that might have been present at different time periods.