Weathering The Wearing down of rocks Learning intentions • LI1-Explain what weathering is. • LI2- Understand what erosion is. Key words in this section Weathering Mechanical weathering Chemical weathering Erosion Freezethaw action Acid Weathering and erosion • The rocks and soil of the Earth’s crust are constantly being worn down by processes known as denudation. • The two main processes of denudation are weathering and erosion. https://www.youtube.com/watch?v=JpRS9N-NWsY Weathering • Weathering is the breaking down of rocks and soil that are exposed to the weather. The broken-down material does not move from the place where the weathering occurred. There are two types of weathering: • Mechanical weathering • Chemical weathering Erosion • Erosion is the breaking down of rocks and soil and the transportation of the eroded material. Erosion is caused by: • Moving water (rivers/seas) • Moving ice (glaciers) • Moving air (wind) Mechanical weathering Mechanical weathering breaks up rocks into smaller pieces by putting pressure on the rock. Freeze-thaw action is an example of mechanical weathering. Freeze-thaw action • Freeze-thaw action occurs high up in mountainous areas where there is a lot of precipitation (rain, sleet or snow) and the temperatures regularly rise above and fall below freezing point (0 ºC). Temperatures that repeatedly rise and fall are called fluctuating temperatures. Freeze-thaw action Image: Freeze-thaw action Freeze-thaw action (Example) • Example: Freeze-thaw action occurs in upland areas like Croagh Patrick in Co. Mayo. Temperatures here frequently rise above and fall below freezing point Learning intentions LI1-Explain what weathering is. LI2- Understand what erosion is.
