Chemical Weathering as we know it
Chemical Weathering causes rock to dissolve or otherwise decompose What is the main cause (agent) of chemical weathering? Chemical Weathering in the Tropics
Chemical weathering is weathering that causes any kind of chemical change to the rock. The reddish-orange colour of the soil is a result of oxidation, a chemical weathering process much like the rusting of iron. What is the main agent for chemical weathering? Why would the tropics have a lot of chemical weathering?
Erosion in the Tropics Rainforest soils are very fertile. Trees are harvested and sold or cut and burnt in the hope of creating fertile farm land to grow crops and graze cattle. . These efforts often fail resulting in eroded, useless land.
Who do you think benefits?
Rainforests in the World Welcome to the Burren-- a wonderful example of Chemical Weathering Where is the Burren?
Burren comes from the Irish word ‘Boireann’ meaning ‘rocky country.’ Formation of the Burren
Once upon a time the Burren was lightly wooded and covered with soil. Toward the end of the Stone Age, about 6000 years ago, the nomadic hunter- gatherers began to settle and farm. To do this they cut the trees and used the hills for grazing and growing crops. What do you think happened?
Karst Landscape
The name Karst comes from a limestone area in Western Slovenia with that name. How Rain Weathers Limestone Carbon Dioxide Mixes with Rain to form a weak Carbonic acid Limestone is a Permeable Rock The rain water seeps through weak points, vertical joints and horizontal bedding planes dissolving tiny particles of calcium carbonate and taking it away. This process forms caves. Surface Features
Bare Rock Gently sloping terraces Sudden cliffs Limestone Pavements
Clints and Grikes Clints are the flat topped slabs
Grikes are the cracks between Rivers can not flow on the surface for long. They disappear into Swallow Holes and leave Dry Valleys behind Maps and Swallow Holes
Look at this map for rivers that just stop Where do you think the Swallow Holes are? Pollnagollum in the Burren
The swallow hole Pollnagollum is 6 meters wide and 16 meters deep.
It is the entrance to Ireland’s longest cave system. This picture shows a fenced off, Over 7 Km have collapsed subsidiary entrance to been explored. Pollnagollum.
In this photo look for the vertical joints and horizontal bedding planes of the limestone where the rain seeps through
The Burren– Continued Underground Features Underground Rivers Form Passages and Caves Features of Caves Underground Passages and Caverns How cave features are formed Evaporation of water dripping through the cave leaves behind tiny particles of calcite earlier dissolved from the rock. Stalactites form from water dipping from the ceiling. Stalagmites form when the water drops and then evaporates from the floor.
It can take over 100 years for a stalactite to grow 5cm.
Stalactites Stick Tight to the Ceiling Stalagmites Grow from the Floor When Stalactites and Stalagmites Grow Together they Become Pillars Other Cave Features
“Niagara Falls”
Soda Straws
Curtain
Popcorn Closer to Home- Mitchelstown Caves
Why is the Burren Special? Potholers and Cavers explore underground. Geographers study the limestone features. Historians and archaeologists appreciate the medieval ruins, ring forts, ancient burial chambers, castles, and scenic villages. Tourist enjoy the unusual Karst Scenery and sites like the Cliffs of Moher, Ailwee Cave, and walking on the ‘Green Roads.’ Botanists and Naturalists
Botanists and Naturalists search for rare plants and animals such as the Pine Martin. The Burren hosts 1,100 of the 1,400 species of plants found in Ireland. Typical Irish plant species are found as well as Alpine and Mediterranean species left from geologic history.
Mullaghmore in The Burren National Park -The Controversy-
Note the many turloughs in the photo. Turloughs are seasonal lakes which empty and fill with the changing ground water levels. What do you think?