Description of rocks and landforms

Clach Bun Rudhtair tor, Ben Avon, CairngormsThe geological record

Scotland Comment on this pageis made up of a wide variety of rocks and sediments. These range in age from among the oldest rocks in the world (hard rocks deformed by heat and pressure deep in the Earth more than 3 billion years ago); through rocks formed from sediments (such as sand and mud) and by volcanic activity throughout geological time; to deposits left by glaciers a few thousand years ago, and river, lake and coastal sediments accumulating today.

Fossils, some of which are internationally important, are found in rocks in many parts of Scotland. Some of our rocks also contain important economic resources such as coal and oil, as well as rare and precious minerals.

Scotland’s landforms have been shaped over time by water, wind, waves, ice and landslides. The advance and retreat of glaciers has created many of the landforms we see today – for example, mountain corries, deep lochs and the crag and tail hills on which sit Edinburgh and Stirling Castles. Our varied coastline was formed by many forces including sea level changes caused by glaciation. Today we have the highest cliffs and some of the largest sand dunes in the UK, as well as important mud flats and salt marshes. There is also a great variety of river features formed by a range of river types from steep mountain torrents to meandering channels in the lowlands.

Scotland’s rocks and landforms provide an exceptional record of landscape evolution and environmental change extending back over much of the Earth’s history, and are a unique scientific resource.

Current processes

Our landforms are still evolving. Water, wind and waves, as well as freeze–thaw weathering, continue to shape the land and coast. Minor earthquakes shake the ground, and landslides and flooding rivers periodically alter the landscape.

Flooding and changes in the courses of river channels are characteristic of Highland rivers. Lowland rivers also flood, but their channels are generally more stable. The River Tay discharges the largest volume of water of any British river, and this and other large rivers carry significant amounts of sediment out to the coast.

Scotland’s coasts are made up of 70% rocks and cliffs (hard coasts); 29% gravels, sand and silts (soft coasts); and less than 1% harbours and sea walls. Seventy-five per cent of coasts are broadly stable, whereas sediment is being added to 8% and lost from 12%. Data are lacking for 5%.

Scotland is experiencing net sea level rise, and projections suggest that this will continue at an increased rate over the next few decades. There is evidence that key coastal processes are also changing more rapidly than they did in the last century. Additionally, coastal sediment supply is at an all-time low, in part due to river bank and coastal defences preventing the erosion of fresh sand and gravel.

Scotland has a long history of relatively minor earthquakes. The earliest recorded Scottish event occurred in the 13th century, and the largest, measuring 5.2 on the Richter local magnitude scale, occurred on 28 November 1880 in Argyll. In June 2012, 11 earthquakes were detected in Scotland, with local magnitudes ranging between 0.8 and 1.5 on the Richter local magnitude scale.

Many recent landslides on steep slopes have been initiated during prolonged or extreme rainfall events. Old landslides can also be reactivated during extreme rainfall events, sometimes because the slope has been made unstable through undercutting by rivers, coastal erosion or even human excavation of the slope. Recent high-profile landslides include those affecting the mountain side above the A83 at the Rest and Be Thankful in Argyll.

State of rocks and landforms

There are around 895 important rock and landform sites in Scotland (identified by the Geological Conservation Review GCR). Around 75% of these are protected as notified Earth Science features in SSSIs. The condition of notified Earth Science features is monitored under Scottish Natural Heritage’s (SNH’s) Site Condition Monitoring (SCM) programme initiated in 1998.

  • by 2005, 594 (out of 612) Earth Science features had been assessed and 90% were in favourable condition;
  • by June 2012, 636 (out of 656) features had been assessed, many more than once; 94% were in favourable condition and a further 3% were under positive management to return them to favourable condition;
  • since 2005, 12 features have suffered some form of irreversible damage and two have been entirely destroyed.

There is no routine monitoring of the condition of geodiversity outwith SSSIs, so there is insufficient information available to make an assessment of its state. In addition, there is no monitoring of the many ecosystem services that rocks and landforms provide, nor of how the value of these services may be affected by the many pressures on them.