Weathering Flashcards
What is denudation ?
Denudation is the process of lowering earths land surface through weathering and erosion reducing elevation and relief
What is relief ?
Relief refers to the difference in height of land on the earths surface , and includes mountain , valleys, hills and plains
What is weathering ?
Weathering is the breakdown of rocks , soils and materials through exposure to the weather (rain , frost , ice , snow , wind ) and organisms
What are the 3 categories of weathering ?
Mechanical (physical) , chemical , biological
What are the types of mechanical weathering ?
Freeze - thaw action (frost action)
Exfoliation (onion peeling)
What is freeze-thaw action ?
Freeze-thaw action occurs in areas where temperatures regularly changes between freezing and thawing. Occurs in areas of high altitude and high latitudes
What is latitude ?
Th distance north and south of the equator
What is altitude ?
The height above sea level
When does freeze-thaw ataron occur in Ireland ?
It’s occurs during winter and for much of the the year in mountains ranges
What happens by day during freeze-thaw action ?
During the day , water seeps into joints (cracks) in the rock
What happens by night during freeze-thaw action?
The temperature drops below freezing point. The water freezes and expands. This makes the crack bigger and puts strain on the rock
What happens over time during freeze-thaw action ?
After repeated freezing and thawing of water , over many years , the rock splits. Sharp jagged piece , called scree , break off. They role down the mountainside and collect in piles at the bottom of the slope
What is exfoliation ?
Occurs where rock layers peel off due to repeated heating and cooling , causing expansion , contraction and eventual cracking
Where does exfoliation happen ?
Happens in areas where temperatures are extremely high during daytime ad very low at night , e.g.deserts
What is chemical weathering ?
Chemical weathering happens when rock is broken down by chemical reactions.
What are examples of chemical weathering ?
Carbonation , oxidation
How does carbonation occur ?
Carbonation occurs wen carbon dioxide (CO2) weathers rocks like limestone and chalk
Rainwater mixes with CO2 to create carbonic acid , which dissolves calcium carbonate, limestone can contain up to 95% calcium carbonate.
The carbonic acid changes calcium carbonate into soluble calcium bicarbonate. This process is slower but more effective in cold water , which holds ore CO2
What are the steps of carbonation?
CO2 + H2O = H2CO3 (carbon dioxide + water = carbonic acid )
Carbonic acid dissolves calcium carbonate into calcium bicarbonate
What is oxidation?
Oxidation is a chemical weathering process , oxygen changes minerals like iron, forming rust that weakens and breaks down the rock over time
What is lichen?
Lichen is an organism made of a fungus and alga , its cause biological weathering , growing on rocks and producing chemicals that break down (dissolve) the rocks surface
What is a karst landscape ?
A karst landscape is an area of exposed limestone , formed by glaciation. Its is a feature formed due to carbonation
What is an example of a karst landscape ?
The Burren Co.Clare formed by carbonation
What are surface features of a karst landscape ?
Limestone pavement , Clints , grikes , swallow hole
What are the subsurface features ?
Cave , stalactite , stalagmite , pillar (columns)
