The uplands of the British Isles are mostly located in the north and west. They include the Scottish Highlands, the Lake District of northwestern England, Snowdonia in North Wales and the mountains of Ireland. Large parts of these regions are composed of older, harder igneous rocks such as granite. Despite being subjected to glaciation and weathering during the Pleistocene Ice Ages, the rocks have resisted erosion and so have remained as uplands. The plants and animals that live in the upland regions of the British Isles have to cope with harsh weather and cold temperatures.

During the Ice Ages, glaciers merged to form an ice sheet thousands of metres thick in places. As the ice moved across the landscape, it carved deep, U-shaped valleys. The ice also rounded the lower hills, smoothing off the sharp edges and peaks. The results can be seen today in the Scottish Highlands, Snowdonia, Lake District and the Mourne Mountains of Northern Ireland. 

Glaciation also smoothed the hills of the Pennines, the "backbone of England", an area of limestone overlain with gritstone (millstone grit). The ice did not reach as far south as southwest England, where the granite uplands of Dartmoor and Bodmin Moor rise above the surrounding lowlands.
​​​​​​​

Climate has also shaped the British Isles' uplands. In the bitterly cold climate at the tops of mountains, water seeps into cracks in the rocky ground and freezes. As it freezes it expands, and the rock breaks apart. This process, called freeze-thaw weathering, formed the jagged, rocky peaks in the highest mountains of the British Isles. It also forms scree, a mass of loose shards of rock that covers mountain slopes.

Rocky habitats

Some of the British Isles' wildest habitats lie at the tops of mountains, such as the Cairngorms in the Grampian range of the Scottish Highlands. Here, the land is rocky and bare, exposed to the wind and vulnerable to freeze-thaw weathering. Only the hardiest plant life such as lichens and mosses can survive in these tough conditions. Moss campion grows in a low mat or “cushion” shape, which helps the plants to stand firm in windy weather and trap warmth from sunlight. Golden eagles nest in rocky crags and cliffs, and soar over the landscape looking for grouse and mountain hares.

Ancient igneous rocks weather slowly, releasing few nutrients into the soil. These upland soils are often also waterlogged due to the high rainfall, a feature of the climate of Ireland and northern and western areas of Britain. Oxygen levels are low in the saturated soils, so there are fewer decomposers—micro-organisms and earthworms—present to break down dead plant material into nutrients. As layers of undecayed organic matter accumulate, a heavy, acidic soil called peat is formed. Over thousands of years, peat can reach several metres in depth. 

Blanket bog

When rain falls on the peat soil, it causes the land to become further saturated with water, creating bogs, a permanently muddy, swampy habitat. Where bogs form on flat or undulating areas in the uplands, they are known as blanket bogs. A vast area of blanket bog stretches across the most northerly part of Scotland, a region known as the Flow Country. This peatland, the largest in Europe, is home to breeding birds such as dunlins, curlews and golden plovers.​​​
​​​​​​​

The lack of nutrients in peat soil means that plants have to be well-adapted to thrive here. Butterworts are insectivorous (insect-eating) bog plants that “hunt” for extra nutrients by using their sticky leaves to trap insects. Large heath butterflies live on bogs in northern Britain and Ireland, where they feed on the nectar from hare's-tail cottongrass.

Wide areas of moorland stretch over the Scottish Highlands, the Lake District, north Yorkshire, the Pennines, Dartmoor, Exmoor, Bodmin Moor, Northern Ireland and Wales. Covered by peat from dried-out blanket bog or acid soils, moorlands are dominated by heather and tough grasses. These plants are short and strong, and able to conserve water in the drying winds.

​​​​​​​Only a few birds and animals can survive the tough conditions on the moors in winter. Red grouse have feathered legs and feet to protect them from the cold, so they can live here all year round, feeding on the shoots and flowers of young heather plants. Red deer graze the heather all year round, kept warm by their thick winter coats.
​​​​​​​

In spring, moorlands make ideal habitats for ground-nesting birds, because they offer short, scrubby vegetation to nest in and open views for spotting predators. Ring ouzels nest in the heather and feed on moorland berries such as bilberries and rowan. Meadow pipits and skylarks make their nests on the ground in grassy clumps. Merlins and kestrels hunt overhead, keeping watch for smaller birds and rodents. Short-eared owls hunt by day, looking for voles in the moorland grasses.

​​​​​Moorlands are described as semi-natural habitats because they have been shaped by human activity as well as by natural forces such as climate. Most would turn back into woodlands if they were not carefully maintained (which they are, for purposes of grouse shooting and deer stalking). Livestock and deer graze the moors to keep the vegetation short. Strips of heather are burnt in a controlled way every 10–15 years, when the plants become old and woody. This makes room for new heather shoots to grow up in their place.
​​​​​