Landscapes of the Ice Age

Constant change

The “Ice Age” refers to the climate of the last 2.6 million years, known geologically as the Quaternary Period, when large parts of north-west Europe were repeatedly covered by glaciers. During these “glacial” periods, south of the ice, there were swift-flowing, cold rivers and bare tundra. The sparse vegetation fed mammals such as mammoths and woolly rhinos.  The Ice Age, however, was not always cold.  Glacials were interrupted by briefer warm episodes (“interglacials”) when conditions were favourable for a wide variety of animals and plants, as they are today.

The glacial periods of the Quaternary became more severe in the last million years, and glaciers started to form in upland Britain.  Ice sheets gradually built up over much of northern and western Britain before retreating more quickly at the end of each glacial period. The trapping of water in the ice sheets caused sea level to fall: at the height of the last glacial epoch around 20,000 years ago, sea levels were around 130m lower than today.

Conversely, in interglacial times, ice was restricted to mountains and the ice sheets of Antarctica and Greenland. During the last interglacial, around 125,000 years ago, the sea level was several metres higher than today. Despite these fluctuations, the timeline below shows that Britain has been an island for very little of the last 500,000 years. For the majority of this time, animals and humans would have been able to walk from Europe into southern England as the ice receded, then retreat again as the climate cooled.

Huge climatic shifts during this period meant that the area now called Worcestershire was at times entirely covered by an ice sheet several hundred metres thick, with only the tops of the Malvern Hills visible. At other times, the climate was similar to or warmer than today, allowing hippopotamus to bathe in the River Severn.

Ice Age timeline of the last 500,000 years

Reconstructing past landscapes

Neanderthals hunting reindeer at Kemerton, just over 40,000 years ago

It’s not easy to reconstruct past landscapes as subsequent changes often result in the loss, relocation or burial of earlier deposits. In Worcestershire, our knowledge of the Ice Age comes from both geological and archaeological studies of preserved Ice Age deposits and the plant remains, animal fossils and human artefacts they contain.

Scientific dating techniques and geological deposit mapping help us to work out how the hills and rivers changed over time – this gives us the basic lie of the land. The bones of large mammals can then tell us which species inhabited the landscape, which also gives us a general idea about the vegetation that might have grown. Above is a reconstruction of Neanderthals hunting reindeer at Kemerton, just over 40,000 years ago. In order to produce this image, illustrator Steve Rigby drew on the discovery of hundreds of bone fragments and stone tools found around Bredon Hill.

Geological deposits and animal bones are valuable clues, but how can we find out exactly what type of vegetation and plants grew? Microscopic plant remains, especially pollen, and the remains of tiny creatures can provide astonishing details about the immediate area: the abundance or absence of trees and whether bodies of water were still or fast-flowing. Unlike larger animals, many species of insects and snails are adapted to live in very niche, specific habitats. Identifying which of these tiny species were present gives us a much more precise picture of the immediate environment.

Worcestershire’s Ice Age landscapes

Drawings of the Upton Warren insects

80,000 years ago, the lakes at Upton Warren, Wychbold, were still, salty pools. Woolly mammoth, reindeer, and bison came to drink. Silted up and buried for tens of thousands of years, the site was uncovered by gravel extraction in the 1950s. The miniscule remains of insects and fish from Upton Warren were discovered thanks to painstaking sieving of 600kg of mud. Amazingly, 80,000 years after they were buried, the insects still shone as they emerged from the mud. Researchers carefully noted the colours before the specimens dried and faded.

Similar analysis of the sediments around ‘Millicent’, a young adult mammoth discovered during the construction of Strensham Services on the M5, revealed cold-adverse mollusc species. Mammoths tend to conjure up images of snowy barren tundra, but as these temperate snails showed, large mammals can live in a relatively broad range of environments – they are not the most helpful indicators for reconstructing lost landscapes.

Alongside Millicent and the cold-adverse molluscs were pollen grains trapped within the silty sediments. Plants produce pollen of different shapes and sizes, making it possible to identify which species they come from. Due to the small, dense nature of pollen grains and their hard surface, pollen can survive in the ground for thousands of years. Careful analysis of the sediments found at Strensham Services revealed evidence of open and relatively dry grassland with a few shrubs and trees: 200,000 years before the motorway was built, daisies, pinks, buttercups, pine, birch and oak grew. Living in this open grassland and temperature climate, similar to today, were mammoths and red deer.

In addition to topography, flora and fauna we can add another layer – human activity. As organic materials soon rot away, stone tools are our primary evidence for the presence or absence of human activity. Stone tools also offer an insight into the technology our early ancestors used and activities they undertook: what type of animals did they hunt and how? Combine these strands of evidence together and Worcestershire’s long lost landscapes start to come to life.

15.jpgAerial view of the Severn Terraces at Clifton, showing a former river channel (copyright AerialCam)