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The formation of limestone rock occured 300 million years ago.
Limestone areas were once the floor of a warm sea, where layers of dead sea creatures built up over time and were compressed to form limestone rock.
Limestone is a Rock made when sediment, such as sand, mud and pebbles, forms in layers. Over time, these layers are squashed under more and more layers of sediment. Eventually, the layers turn to sedimentary rock that can be formed in deserts, lakes, rivers and seas. formed in layers. It is made up of:
- horizontal blocks called bedding planes
- these are separated by vertical cracks called joints
Limestone is also a A type of rock which allows water to pass through its joints and cracks, eg limestone. meaning water can pass through eroding via the two main processes of
- physical weathering
- The erosion of rocks by chemicals that react with their minerals.
How was limestone rock formed?
- Formed in the Carboniferous period (300 million years ago)
- Limestone areas were once the floor of a warm, shallow sea
- Dead sea creatures drop to the see floor
- Shells, skeletons and coral (containing calcium carbonate) form layers of sediment
- Over time many layers build up
- Layers are compressed to form limestone rock
Watch this to learn how carboniferous limestone is formed.
Formation of carboniferous limestone
Carboniferous limestone is a sedimentary rock composed of calcium carbonate. This rock was formed in the Carboniferous period around three hundred million years ago.
At that time, this land mass would have been the ocean floor of a warm, shallow sea. Over many years, the shells of dead sea creatures were deposited, dropped as sediment onto the ocean floor.
Over long periods of time, these layers were compressed to form limestone rock. It is often rich in fossil deposits, which date back to the Carboniferous period.
Today we can still see evidence of how the rock was formed. On this cliff face of limestone rock, we can see the horizontal bedding planes, which reveal how the rock was laid down millions of years ago.
The different beds were a result of variations in the rate that the sediment was deposited, the amount of sediment was laid down at different rates depending whether it was a warm or cold climatic spell.
There are also vertical cracks in the rock called joints which were formed later by movements in the Earth's crust. This limestone rock was shifted and reshaped to create the Great Scar Limestone, which is the name given to the rock here in the Yorkshire Dales. This was a result of powerful natural forces which cause shifts in the Earth's crust. These tectonic movements shape the continental land masses over millions of years.
The limestone rock was shifted, raised and reshaped.
What do horizontal bedding planes show?
Horizontal bedding planes reveal how the rock was laid down millions of years ago.
The different beds were a result of variations in the rate that the sediment was deposited, the amount of sediment was laid down at different rates depending whether it was a warm or cold climatic spell.
How is limestone eroded?
Limestone is a Rock made when sediment, such as sand, mud and pebbles, forms in layers. Over time, these layers are squashed under more and more layers of sediment. Eventually, the layers turn to sedimentary rock that can be formed in deserts, lakes, rivers and seas. formed in layers. It is made up of:
- horizontal blocks called
- vertical cracks called A crack in a rock formed when the rock dried out or pressure is released.
Limestone is also a A type of rock which allows water to pass through its joints and cracks, eg limestone. which means that water can pass through its joints and cracks - it is eroded by weathering processes:
- Chemical weathering
- Physical weathering
Limestone is made of A chemical compound found in minerals and rocks, like limestone, marble and chalk. which is When a solid becomes absorbed and a part of a liquid. by rainfall, a weak When the gas carbon dioxide mixes with water to form an acidic solution.. This process is called chemical weathering.
Chemical weathering
The The erosion of rocks by chemicals that react with their minerals. of limestone pavement is shown by the formula:
(limestone + carbonic acid → calcium hydrogen carbonate When chemicals in the seawater dissolve minerals in the rocks, causing them to break up.)
- Rainwater absorbs carbon dioxide from the air
- This creates weak carbonic acid
- Carbonic acid dissolves the mineral in limestone
- This erodes the surface and widens bedding places and joints
Physical weathering
- Water enters cracks in the limestone
- When temperatures drop the water freezes and expands
- When temperatures rise the ice thaws and contracts
- Over time this repeating freeze-thaw process breaks off pieces of rock
Upland limestone is also eroded by the action of glaciers through abrasion and by the action of water through corrasion and hydraulic action.
Limestone landscapes
If A type of sedimentary rock formed between 363 and 325 million years ago. is capped by Rocks that do not allow water to pass through them, e.g. granite., surface streams can run on to limestone.
This water disappears from the surface, either by seeping through joints in the limestone or as streams disappearing down through swallow holes.
It is the action of water which is responsible for many of the distinctive features of upland limestone scenery.
Recap
The formation of limestone rock happened 300 million years ago.
Limestone areas were once the floor of a warm sea, where layers of dead sea creatures built over time and were compressed to form limestone rock.
Limestone is a Rock made when sediment, such as sand, mud and pebbles, forms in layers. Over time, these layers are squashed under more and more layers of sediment. Eventually, the layers turn to sedimentary rock that can be formed in deserts, lakes, rivers and seas. formed in layers. It is made up of:
- horizontal blocks called bedding planes
- vertical cracks called joints
Limestone is also a A type of rock which allows water to pass through its joints and cracks, eg limestone. meaning water can pass through eroding via the two main processes of
- physical weathering
- The erosion of rocks by chemicals that react with their minerals.
More on Upland limestone landscapes
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