The Changing World PDF - Structure and Layers of the Earth
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This document provides an informative overview of the structure of the Earth, from the crust to the inner core. It explains the evidence and causes of plate tectonics and various types of plate boundaries. The document is a good start to an Earth science study session.
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Structure and Layers of the Earth Crust: Outermost layer, thin and rigid, divided into continental and oceanic crust. Thickness: 5-70 km. Mantle: Beneath crust, composed of semi-solid rock, extends to 2,900 km deep. Outer Core: Liquid layer, mostly iron and nickel, 2,200 km thick. Inner C...
Structure and Layers of the Earth Crust: Outermost layer, thin and rigid, divided into continental and oceanic crust. Thickness: 5-70 km. Mantle: Beneath crust, composed of semi-solid rock, extends to 2,900 km deep. Outer Core: Liquid layer, mostly iron and nickel, 2,200 km thick. Inner Core: Solid due to immense pressure, mostly iron and nickel, 1,220 km radius. Plate Tectonics Evidence Alfred Wegener's Continental Drift Theory: Continents fit together like puzzle pieces. Fossil evidence: Same species on separated continents. Seafloor Spreading: Mid-ocean ridges reveal new crust forming as magma rises. Earthquakes and Volcanoes Distribution: Earthquakes and volcanoes occur along plate boundaries. Paleomagnetism: Earth's magnetic field reverses over time, providing a timeline of plate movement. Continental Plate Movement Causes Convection Currents in the Mantle: Hot magma rises, cools, and sinks, driving tectonic plate movement. Slab Pull: Gravity pulls denser oceanic plates downward at subduction zones, dragging the plate. Ridge Push: New crust forms at mid-ocean ridges, pushing older crust away, driving plate movement. Seafloor Spreading Structures and Processes Mid-Ocean Ridge: A continuous mountain range in the ocean where magma rises to the surface. Formation of New Crust: As magma rises, it cools and solidifies, creating new oceanic crust. Magnetic Stripes: Earth's magnetic field reverses periodically, creating symmetrical magnetic stripes. Rock Ages: new crust is constantly being formed Types of Plate Boundaries and What Occurs at Each 1. Divergent Boundaries (plates move apart) 2. Convergent boundaries (plates move towards each other) 3. Transform Boundaries (plates slide past each other) Plate Boundaries and Seismic/Volcanic Activity Convergent Boundaries: Cause deep earthquakes and volcanic eruptions due to subduction zones. Divergent Boundaries: Earthquakes occur as plates move apart, with volcanic activity common. Transform Boundaries: Earthquakes result from plate friction. Volcano Terms Overview Active Volcano: Currently erupting or showing signs of future eruption. Dormant Volcano: Not recently erupted but could re-erupt. Extinct Volcano: Not expected to re-erupt due to lack of magma supply.
