Transcript Landforms
The Earth’s Physical Processes The Earth Third planet from the Sun ◦ Only planet that can support life Atmosphere Gases that extends 6,000 miles above the surface ◦ Allows us to breathe ◦ Composed of 78% nitrogen, 21% oxygen, and 1% other gases Hydrosphere About 70% of the Earth’s surface is water ◦ Oceans, rivers, lakes, etc. Biosphere All people, animals, and plants that live on the Earth’s surface Lithosphere About 30% of the Earth’s surface is land ◦ Also includes the ocean basins Layers of the Earth CONVECTION occurs in the mantle… heat rises causes a circular movement of semi-solid magma Plate Tectonics…. Puzzle Pieces! The process of continental drift and magma flow that creates the Earth physical features Pangaea to Today!! Types of Plate Movement Convergent= converges or moves together! Divergent= diverges or moves apart! Transform= slides past each other! Types of Plates 1.) Oceanic: heavier plates located under the ocean II.) Continental: lighter plates under the continents Convergent Boundaries Subduction: when one plate sinks beneath another plate Accretion: when material piles up because of subduction Plate Tectonics (cont) Subduction (Convergent Plates) ◦ One continental plate sinks when they collide ◦ mountains are formed EX: Himalaya Mountains (Two continental plates) Plate Tectonics (cont) Subduction (or Convergent Plates) ◦ Heavier sea plates dive under lighter continental plates Creates volcanic mountains EX: Andes Mountains(Oceanic and continental) Plate Tectonics (cont) Accretion Another instance of continental and sea plates meeting Creates underwater mountains, trenches, and volcanoes Buildup can cause continents to grow Plate Tectonics (cont) Spreading (or Divergent Plates) ◦ Sea plates pull apart creating rifts allowing magma to flow Creates underwater volcanic mountains or ridges Pushes continents apart Plate tectonics Subduction and seafloor spreading cause trenches (underwater valleys/canyons) EX: Mariana Trench in Pacific Ocean Plate Tectonics Spreading of two plates…Rift Valleys EX: Great Rift Valley in Africa Plate Tectonics (cont) Transform: Faults (cracks in the Earth!) ◦ Occurs when plates grind past each other As the plates slide, earthquakes acre created Tsunamis are caused by transform movement under the ocean Plate Tectonics EX: San Andreas Fault Plate Tectonics EX: Japanese Tsunami Plate Tectonics “Hot Spots”: weak plate areas where magma breaks through EX: Hawaiian Islands Ring of Fire Area of SEISMIC (plate moving) activity around the Pacific Plate that causes volcanoes, earthquakes, and tsunamis Forces that Affect the Earth Weathering – physical or chemical process that breaks down the earth’s surface ◦ Physical –rock breaks down but does not change what it’s made of EX: water seeps into rocks, freezes, expands, and breaks rocks ◦ Chemical – combination of elements to transform or breakdown minerals EX: water and CO2 combine to dissolve limestone creating caves Forces (cont) Erosion – process of carrying rock away ◦ Wind – movement of dust, sand, and soil from one place to another Effect: moves soil from dry or deforested areas AND moves it somewhere else… Making it rich! EX: Dust Bowl in 1930s Great Plains Erosion Contd… ◦ Glacial – large bodies of ice slowly move across the Earth’s surface EFFECT: Carves valleys in mountains AND/OR creates dams and glacial lakes EX: Rocky Mountain glacial valleys ◦ Water – fast moving rain, rivers, streams, and oceans wears away the surface Effect: gullies, valleys, canyons EX: Grand Canyon Forces (cont) Soil Building – layers of different types of rock and soil that build up over the years WHY? rocks break down due to weathering mix with decaying plants and animals to create soil ◦ Different regions have different types Desert sands will not support life Grasslands are among the best