Story · Environment map · about 3 min
What is under your feet?
Beneath the soil, the UK has some of the most varied geology of any country its size. This story reads the British Geological Survey's national map: what the rock is, how old it is, and what lies on top.
Rock, coloured by age
Each colour is a geological age, using the international standard colours. Of the bedrock mapped in the UK, 59% is Carboniferous or older, and 27% is Jurassic or younger. The single biggest slice is Carboniferous, at 18%. Click anywhere for the named rock unit and its age.
Old in the north and west, young in the south-east
Of all the Jurassic and younger rock, 83% lies in south-east England. The younger, softer rocks of the Cretaceous chalk and Jurassic limestone and clay sweep across that corner, while the older, harder rocks form the uplands to the north and west.
Cracks and dykes
The map records 2,741 faults, 138 of them thrust faults where older rock has been pushed over younger. Purple marks the thrusts. The dykes are narrow sheets of igneous rock that filled cracks: 3,263 of them, 37% of them Palaeogene, from the time the North Atlantic began to open. The source records no fault names, so none are shown.
The loose ground on top
Most of the ground you stand on is not bedrock but a covering laid down in the last two million years, and it matters more day to day than the rock far below: it is what your foundations sit on, how well your garden drains, and how easily a slope erodes or subsides. Of the mapped covering, 56% is till, left by glaciers, 12% is river alluvium and 12% is peat.
For classrooms and curious minds
Questions to talk about, alone or in a group.
- Why does the loose ground on top matter more day to day than the rock beneath it?
- What does the age of a rock tell you about how the landscape formed?
Try it on the map: Look at the bedrock where you live. How old is it, and does the scenery match what you would expect?
The figures above are calculated from the datasets listed on Data & sources and are approximate: many map layers are modelled or interpolated. Read each layer’s caveats on the map.