Presentation on theme: "Constructive & Destructive Forces on Landforms"— Presentation transcript:
1 Constructive & Destructive Forces on Landforms 5-3.1
2 Two Types of ForcesDestructive Forces: processes that destroy landforms.2 types: Slow (weathering) and Fast (Erosion)Ex. landslides, volcanic eruptions, earthquakes, floodsConstructive 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
3 WeatheringWeathering PicturesWeathering: a slow, destructive force that breaks rocks into smaller pieces called sediments. Can by physical (mechanical) or chemical.Keywords:wear down, breakapart
4 Mechanical weathering: the breaking of rock into smaller pieces by forces due to gravity, ice, plant roots, or other physical forces.
5 Mechanical Weathering: Rock is physically broken into smaller piecesSmall pieces have same composition as the original rockVery slow
6 Mechanical Weathering: Caused by…(Agents)Freezing and ThawingRelease of PressureGrowth of PlantsAnimalsAbrasion – Grinding away of rock by other rock particles that are carried by water, ice, wind, or gravity
7 Chemical Weathering: the changing of materials in a rock by chemical processes. Rock particles have different mineral make-up than original rock
8 Chemical Weathering: Caused by…(Agents) H2O MOST important Oxygen (O2)Carbon Dioxide (CO2)Living organismsAcid Rain very rapid
9 Agent Type Description MechanicalRock particles wear away rockChemicalForms from coal, oil, and gas burningFreezing/ThawingBreaks rock by ice wedgingCarbon DioxideForms carbonic acid in waterWeathers marble and limestoneBurrowing in the ground breaks rockPlant growthRoots pry apart cracks in rockLiving OrganismsProduce weak acid that weathers rockOxygenCauses rust on some rockSun or forest fire causes rock to crack
10 Rates of Weathering: Type of rock Climate Minerals that make up the rock determine how fast it weathersClimateOccurs faster in wet climates & at high temperatures
11 ErosionGrand Canyon VideoErosion: the destructive movement of materials away from one place by wind, water, ice and gravity.Wave Erosion- caused by waterWind Erosion (Dust Storm)
12 LandslidesLandslides: occur when gravity quickly pulls rock and dirt downhill.
13 FloodsFloods: a great flow of water over an area that is usually dry land.
14 Erosion & DepositionDeposition: the placing of materials in a new place (constructive force).Ex. Sandbars
15 Water Erosion & Deposition River Delta- Deposits of sediment at the mouth of the Mississippi River creating new land called a delta.
16 Wind Erosion & Deposition Sand Dunes- sand is moved by windDesert Sand DunesOcean Sand Dunes
17 Mass Movement: Caused by gravity Process that moves sediment downhill 4 typesLandslide - SlumpMudslide - Creep
18 Landslide: Most destructive When rock & soil slide quickly down a steep slope
19 Mudflow: Rapid downhill movement of H2O, rock, and soil Often occurs after heavy rains