Adventure landscapes
Underworld
This section looks at limestone formations and the physical characteristics that make them so unique.
Key questions:
- How do limestone caves form?
- What physical features are found in caves?
Key Concepts:
Physical & human processes
How do limestone caves form?
The underground caves that characterise many areas of limestone scenery are formed due to the structure and the compositon of limestone and the way it interacts with water. Limestone contains both joints and bedding planes which run perpendicular to each other splitting the rock into well-defined blocks and making it permeable. Both joints and bedding planes provide lines of weakness along which water can flow and as it does so its slight acidity dissolves the limestone with which it comes into contact. At the surface the joints within the limestone pavement widen to produce features known as grykes separating the limestone blocks, clints.
Water flowing over the surface plunges down the joints which it rapidly enlarges to form swallow or sink holes. Underground the processes continue and as limestone is dissolved along the route of the submerged stream caves, caverns, waterfalls and lakes begin to form. Carboniferous Limestone in both the Yorkshire Dales and Derbyshire form spectacular caverns such as Gaping Ghyll and Titan. Eventually the underground stream may descend to an impermeable layer such as a clay and can emerge where the water table intersects with the hillside as a spring or river (a resurgence) such as the River Axe at Wookey Hole in the Mendips or the River Aire which reappears from under Malham Cove in the Yorkshire Dales. Some cave systems may also have been influenced by changes in the level of the water table and in volumes of water passing through as climate has changed.
What physical features are found in caves?
Within the caves water continues to play a crucial role in shaping the scenery and the growth of stalactites and stalagmites (speleothems). Gaping Ghyll contains extensive speleothem formations in the "Stalactite and Stalagmite Chambers".
Click on an activity:
Starter
Main activity
Plenary
Interactives:
Limestone landscapes: Formation
Downloads:
Glossary of caving terms (detailed)
Glossary of caving terms (less detailed)
Draw what you hear
Video: