The UK's Physical Landscape Overview

A Country Built from Rock and Ice

Stand on Snowdon and look north-west: hard, pointed mountains and deep glacial lakes. Stand on the South Downs and look south: gentle, chalk-and-clay hills with rolling farmland. The two views are nothing alike, yet they are part of the same small country. The reason is that the UK’s landscape has been built up over hundreds of millions of years by three forces: geology, past climate processes (especially glaciation), and human activity. Together these explain why the north and west of the UK are mostly upland, while the south and east are mostly lowland.

Three Rock Families

Geographers divide rocks into three groups based on how they form. Igneous rocks like granite formed when molten rock cooled inside or above the Earth’s crust. They are hard, resistant and tend to make uplands — granite forms the moorlands of Dartmoor and the mountains of the Cairngorms. Sedimentary rocks like chalk, clay and limestone formed from layers of compressed sediment, often laid down in ancient seas. They are softer and more easily worn down, so they tend to make lowlands. Metamorphic rocks like slate and schist were created when other rocks were heated and squeezed underground; they form parts of the Welsh and Scottish highlands.

The Tees-Exe Line

A useful piece of mental geography is the Tees-Exe Line — an imaginary diagonal from the mouth of the Tees in north-east England to the mouth of the Exe in Devon. Roughly speaking, the older, harder rocks lie north and west of the line, forming uplands like the Lake District, Pennines, Snowdonia and the Scottish Highlands. The younger, softer rocks lie south and east, forming lowlands such as the London Basin, the Fens and the Wessex chalk downs. Of course there are exceptions — Dartmoor is an upland granite outcrop south of the line, and parts of the Cumbrian coast are low-lying — but the line works as a quick rule of thumb.

The Last Ice Age

The UK’s landscape has been finished off by ice. During the most recent glacial period (the Devensian, ending around 11,500 years ago) much of the UK was buried under ice up to a kilometre thick. Glaciers carved deep U-shaped valleys, cirques (the basins where glaciers formed), and lakes such as Llyn Idwal in Snowdonia and Wast Water in the Lake District. The ice carried huge amounts of rock, scouring some areas down to bare bedrock and dumping the debris elsewhere. Glacial till covers much of East Anglia and the Vale of York, creating fertile farmland on flat ground.

Post-Glacial Processes

Once the ice had melted, other processes took over. Weathering — especially freeze-thaw on exposed mountain tops — loosens rock fragments. Mass movement such as landslides, mudflows and rockfalls slowly drags loose material downhill. Rivers re-carved valleys that had been widened by ice, leaving small, fast streams sitting in oversized U-shaped valleys (a feature called a misfit stream). On exposed coasts, the post-glacial sea has steadily eaten cliffs back. The UK’s landscape is still being shaped today — just much more slowly than during the ice age.

The Human Landscape

People have reshaped the UK landscape too. Forests once covered most of lowland Britain; today only about 13% of the UK is forested, and most of that has been planted. Lowland landscapes have been ploughed, drained and hedged into farmland. Uplands have been cleared for sheep grazing — the ‘wild’ moors of the Yorkshire Dales and Lake District are largely the result of livestock keeping the trees down. Cities like London, Birmingham and Manchester have buried natural landscapes under brick, tarmac and concrete. Even apparently natural features — the Norfolk Broads — turn out to be flooded medieval peat diggings.