Physical Geography- Chemical Weathering

Explain how the process(es) of mechanical weathering or chemical weathering help to shape the Irish landscape.

Chemical weathering refers to the disintegration of rock as a result of chemical changes in the mineral composition if the rock. The four main processes of chemical weathering are: solution, hydration, oxidation and carbonation. Carbonation is caused by rainwater that has absorbed carbon dioxide from the atmosphere to form a weak carbonic acid. The slightly acidic rainwater dissolves certain minerals in the rock.

Carbonation has shaped the Irish landscape in the Burren, Co. Clare. The Burren is Ireland's most famous limestone region. It was formed 300 million years ago during the carboniferous period. The bones of living things got compressed, compacted and cemented together to form a limestone pavement. Limestone is a permeable rock, which means water can pass through it. Carbonation can be seen above the surface in many areas of the Burren. Due to carbonation, clints and grikes can be seen in the strata of the limestone. Grikes are vertical cracks that develop along a joint. They are seen in between slabs of limestone known as clints. Karrens may also be evident when a small hollow forms on the surface of the limestone clint. They are caused by rainwater and acids dissolving the rock. 

Carbonation has also created a distinctive landscape below the surface of the Burren. It can lead to caves forming such as the Ailwee Caves. This happens when a river disappears underground through a swallow hole, leading to a passage being created. Many dripstone features can be seen in these caves or caverns, such as stalactites, stalagmites and pillars. Stalactites form when drops of water containing dissolved limestone seep through cracks in the cave roof. These drops lose carbon dioxide, deposit calcite and hang down from the cave roof. Stalagmites are formed when water droplets fall to the cave floor. They deposit calcite and build up from the floor. Pillars are formed when stalactites and stalagmites grow towards each other and eventually meet.