Transcript File
5 minute check November 6, 2013 What is the difference between a constructive and a destructive force? 4.3 - The student will describe how landforms are the result of a combination of constructive and destructive processes. Destructive Forces: processes that destroy landforms. ◦ 2 types: Slow (weathering) and Fast (Erosion) ◦ Ex. landslides, volcanic eruptions, earthquakes, floods Constructive forces: forces that build up an existing landform or create a new one. ◦ Caused by: water, gravity, wind and glaciers. ◦ Ex: deposition, landslides, volcanic eruptions, floods Destructive forces – destroy and wear away landmasses through processes like weathering and erosion. ◦ Weathering – wearing by wind, precipitation, freezing/thawing ◦ Erosion – wearing down & carrying away of land by natural forces Destructive forces are those that are recycling the Earth, like Earthquakes and plate movement. One example is when wind erodes or takes away some of the sand on a sand dune or beach. Farming is a destructive process, because the soil has to be dug up and moved around in order to grow plants. Mining is another destructive process, because we dig holes into the earth or blow up parts of the earth and/or caves in order to get what we want. Weathering Pictures Weathering: a slow, destructive force that breaks rocks into smaller pieces called sediments. Can be by a physical (mechanical) or chemical process. Mechanical weathering: the breaking of rock into smaller pieces by forces due to gravity, ice, plant roots, or other physical forces. Grand Canyon Video Erosion: the destructive movement of materials away from one place by wind, water, ice and gravity. Wave Erosion- caused by water Wind Erosion (Dust Storm) Landslides: occur when gravity quickly pulls rock and dirt downhill. Floods: a great flow of water over an area that is usually dry land. Volcano: an opening in the Earth’s crust through which steam, lava and ashes erupt. Cause both destructive and constructive changes to landforms. Mount St. Helens Video Saint Helen’s Before Saint Helen’s After Volcanoes can be constructive, but also destructive… Earthquakes: the shaking of Earth’s surface caused by the release of energy along a fault. San Andreas Fault, California Constructive forces – shape earth’s surface by building up mountains, volcanoes and other landmasses caused by plate movements. It makes positive changes! One example of a constructive process is when sand is deposited onto a river bank by the running water. This builds up the river bank, making it higher. Another example of a constructive process is a volcano erupting. This builds up the land around the volcano, making it higher. Any type of geological event where land is uplifted. Uplift- the movement of fault block (normal fault) Mountain of two plates Building- the convergence Deposition: the placing of materials in a new place (constructive force). Ex. Sandbars River DeltaDeposits of sediment at the mouth of the Mississippi River creating new land called a delta. Sand Dunes- sand is moved by wind Desert Sand Dunes Ocean Sand Dunes Grand Canyon – sandstone rock New York – lichen on granite; secrete chemicals that break down rock The Bernard Glacier in Alaska's Saint Elias Mountains 5 minute check November 7, 2013 Give an example of a Constructive and a Destructive force? 4.3 - The student will describe how landforms are the result of a combination of constructive and destructive processes. Destructive Forces: processes that destroy landforms. ◦ 2 types: Slow (weathering) and Fast (Erosion) ◦ Ex. landslides, volcanic eruptions, earthquakes, floods Constructive forces: forces that build up an existing landform or create a new one. ◦ Caused by: water, gravity, wind and glaciers. ◦ Ex: deposition, landslides, volcanic eruptions, floods Any type of geological process that destroys or moves land Weathering- the process of breaking down rock into smaller pieces ◦ Chemical- acid rain breaks down rocks Example: Granite gravestones and statues ◦ Mechanical- the use of mechanical force to break apart rocks Example: plant growing in sidewalk Any type of geological process that destroys or moves land Erosion- the process of moving sediment ◦ Glacial Erosion- glaciers push rocks and move them downhill Example: Alaska glaciers and alpine glaciers ◦ Wind Erosion- wind picks up and carries sediment Example: moving sand dunes ◦ Gravity Erosion- gravity forces rocks and large landmasses downhill Example: landslides Constructive forces: forces that build up an existing landform or create a new one. ◦ Caused by: water, gravity, wind and glaciers. ◦ Ex: deposition, landslides, volcanic eruptions, floods Nevada’s Great Basin National Park A- Constructive B-Destructive pine tree eroded by wind Nevada’s Great Basin National Park A- Constructive B-Destructive pine tree eroded by wind Lake Tahoe – created by a normal fault A- Constructive B-Destructive Lake Tahoe – created by a normal fault A- Constructive B-Destructive Sierra Nevada Mountains A- Constructive B-Destructive Sierra Nevada Mountains A- Constructive B-Destructive Spring Mountain Range (Mt. Charleston) A- Constructive B-Destructive Spring Mountain Range (Mt. Charleston) A- Constructive B-Destructive Red Rock Canyon A- Constructive B-Destructive Red Rock Canyon A- Constructive B-Destructive Valley of Fire A- Constructive B-Destructive Valley of Fire A- Constructive B-Destructive Grand Canyon A- Constructive B-Destructive Grand Canyon A- Constructive B-Destructive 5 minute check November 8, 2013 What are all the names for the hot stuff that comes out of volcanos? 4.3 - The student will describe how landforms are the result of a combination of constructive and destructive processes.