Upland limestone - surface features

Limestone pavements

Features of Limestone LandscapeThe formation of a limestone pavement

Limestone pavement, Yorkshire Dales
Limestone pavement, Yorkshire Dales

  • During glaciation, ice scraped away the topsoil to expose the bare rock underneath.
  • As limestone is a permeable rock, water is able to seep down through the rock.
  • Rainwater is a weak carbonic acid which reacts with the limestone dissolving the stone, enlarging joints and bedding planes.
  • On the surface the chemical weathering widens and deepens cracks to form grykes.
  • This leaves exposed blocks of limestone called clints and the resulting pattern of blocky rock is called a limestone pavement, eg Malham Cove.

Potholes/swallow holes

Gaping Gill, Ingleborough, North Yorkshire
Gaping Gill, Ingleborough, North Yorkshire

  • Surface water and rain do not flow far on exposed limestone as they rapidly infiltrate into the rock and soil.
  • Where a joint or intersection of joints has been greatly weathered or dissolved, water can pass down through the limestone.
  • A stream travelling over an impermeable rock will very quickly disappear when it has to travel over limestone.
  • These swallow holes can be many metres deep leading down to a series of underground features.
  • An example of a swallow hole in the Yorkshire Dales is Gaping Gill.

Upland limestone drainage features

Intermittent drainage

Scars and scree

Yorkshire dalesYorkshire dales

Scars are exposed cliffs of limestone. They were created during the last ice age, when huge sheets of ice scraped away the soil-covered spurs in many valleys in the Yorkshire Dales.

The exposed surface is affected by freeze-thaw action on the well-jointed limestone. Water enters the cracks and if it freezes, expands. As the water expands, so do the cracks.

Repeated freezing and thawing eventually breaks off rock, and at the bottom of the scar cliff a talus or scree slope is formed.

Limestone landscape

In the diagram below you will see some surface feature of limestone landscape.

Surface features of limestone landscapeSurface features of limestone landscape