Chapter 5- Chemical Weathering By Rain Water: The Burren

Question 1

How is Limestone weathered by rainwater?

Answer 1

1. As rainwater passes through the atmosphere, it takes in carbon dioxide and then becomes a weak carbonic acid.
2. This acid reacts with calcium calcium carbonate in limestone, causing the limestone to be dissolved slowly.
3. Limestone is permeable* this means that limestone allows water to pass through it.
4. It is easy for this rainwater to pass through the many vertical joint and horizontal bedding planes in Limestone.

Question 2

What are Grikes?

Answer 2

Grikes are deep grooves that criss-cross the bare limestone pavements.

These are vertical joints in the limestone that have been widened by rainwater weathering.

Question 3

What are Clints?

Answer 3

The blocks of Limestone that separate the Grikes are known as clints

Question 4

What are Swallow Holes?

Answer 4

The Grikes may become enlarged into vertical holes called swallow holes

Question 5

Give an example of a swallow hole.

Answer 5

Example: Pollnagcolm is 6 metres wide and 16 metres deep

Question 6

What are Passages?

Answer 6

Long tunnels formed by underground water dissolving the limestone

Question 7

What are caves/caverns?

Answer 7

Caves/caverns are when passages become enlarged and form large caves/caverns.

Question 8

How are stalactites formed?

Answer 8

1. Drops of water containing dissolved limestone may form slowly and evaporate on the roof of a cave.
2. Each drop leaves a tiny speck of calcite* (from calcium carbonate) attached to the roof
3. Over thousands of years, these speck develop into stalactites

Question 9

Define Stalactites.

Answer 9

Slender columns of calcite which hang from the cave roof.

Question 10

How are stalagmites formed?

Answer 10

When drops of water fall onto the cave floor and evaporate they cause calcite to build up in the form of stalagmites.

Question 11

Define stalagmites.

Answer 11

Thicker columns which form on the floor directly under stalactites

Question 12

What are pillars?

Answer 12

When stalactites and stalagmites may grow until they meet to form pillars

Question 13

Why do people visit the Burren?

Answer 13

• Geographers study the limestone features
• Potholers and Cavers explore the underground cave systems
• Botanists and naturalists examine the rare plants that grow there
• Tourists admire the unusual karst scenery

Question 14

Where else experiences a great deal of chemical weathering?

Answer 14

Hot, wet regions within the tropics experience a lot of chemical weathering, which gives them a special kind of soil called tropical red soil.

Examples: the Amazon and Congo river basins

Question 15

Define karst.

Answer 15

A place where the soluble limestone is exposed at the surface