Weathering 8 8 0 Weathering Learning Intentions You

Weathering 8

8. 0 Weathering Learning Intentions You will be able to: § Discuss with the aid of diagrams the process and effects of mechanical, chemical and biological weathering. § Describe how the physical landscape of the Burren has attracted tourism to this region. 8

8. 1 The Landscape Our landscape is dynamic. This means it is always changing. Weathering 8

8. 2 Denudation Weathering 8 Rocks on the earth’s surface are constantly being worn down by a number of processes known as denudation. The two main process in denudation are weathering and erosion. 2 1 BY Water Wind Ice Gravity 1 Weathering is a chemical, mechanical or biological process in which rocks exposed to weather are worn down.

8. 2 Denudation Weathering 8 Rocks on the earth’s surface are constantly being worn down by a number of processes known as denudation. The two main process in denudation are weathering and erosion. 2 1 BY Water Wind Ice Gravity 2 Erosion is the breaking down and carrying away of weathered soil, rock and other materials on the earth’s surface

8. 2 Denudation Weathering 8 Mechanical Weathering Freeze-thaw in action 1 By day, water collects in rocks in the cracks. 2 At night the water freezes and expands. 3 Repeated freeze-thaw action causes the rocks to shatter. It falls to the bottom of the slope as scree.

8. 2 Denudation Weathering Chemical Weathering 1 2 3 4 5 1 As rainwater falls and passes through the air, it dissolves carbon dioxide. 8

8. 2 Denudation Weathering Chemical Weathering 1 2 3 4 5 2 Carbon dioxide mixes with the rainwater to form a weak carbonic acid. 8

8. 2 Denudation Weathering 8 Chemical Weathering 1 2 3 4 5 3 Limestone in the ground contains calcium carbonate. When the weak carbonic acid in the rainwater falls onto the limestone, a chemical reaction takes place.

8. 2 Denudation Weathering 8 Chemical Weathering 1 2 3 4 5 4 The calcium carbonate in the limestone begins to dissolve. This process is known as carbonation.

8. 2 Denudation Weathering 8 Chemical Weathering 1 2 3 4 5 5 Limestone is a permeable rock, which means that rainwater can easily pass through it. It has vertical cracks, which are known as joints, and horizontal bedding planes.

8. 2 Denudation Weathering Chemical Weathering: Karst landscapes The effects of carbonation are seen in karst landscapes The overlying plants have been removed and the limestone rock is exposed The Burren in County Clare is an example of a karst region The Burren, Co. Clare 8

8. 2 Denudation Weathering 8 Burren: Surface features The bare, rocky karst surface is called a limestone pavement The pavement is made up of clints and grikes Clints and grikes Limestone pavement

8. 2 Denudation Weathering Burren: Surface features When a river enters a karst landscape, it can disappear underground through grikes The grikes become enlarged, forming big vertical holes known as swallow holes Poll na g. Colm is an example of a swallow hole in the Burren Swallow hole 8

8. 2 Denudation Burren: Underground features Weathering 8

8. 2 Denudation Weathering 8 Biological Weathering Biological weathering is where rocks are worn away by animals, plants and living organisms. Trees and plants can grow within the cracks in rocks As the roots grow, they push open the cracks makng them wider and bigger Over time, the growing plant or tree eventually breaks the rocks apart

8. 3 Tourism in the Burren Weathering 8 The Burren attracts tourists from all over the world This has an economic and environmental impact Tourists in the Burren

Weathering Video: Freeze-Thaw Action 8