Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Post-glacial rebound wikipedia , lookup
Geomagnetic reversal wikipedia , lookup
History of geomagnetism wikipedia , lookup
Geochemistry wikipedia , lookup
Age of the Earth wikipedia , lookup
History of geology wikipedia , lookup
Algoman orogeny wikipedia , lookup
Oceanic trench wikipedia , lookup
Tectonic–climatic interaction wikipedia , lookup
PLATE TECTONICS: PLATE BOUNDARIES LAYERS OF THE EARTH 1. Crust (brown/tan) 2. Mantle (light & dark orange) 3. Core (yellow & white) LAYERS OF THE EARTH Lithosphere { Crust and upper mantle make up the LITHOSPHERE rigid plates (OCEANIC & CONTINENTAL plates) Beneath the lithosphere is the ASTHENOSPHERE plastic” mantle (flows, moves the plates) higher temperature & pressure low temperature & pressure PLATE TECTONICS the surface of the Earth is made of rigid plates Size and position of plates can change over time PLATE BOUNDARIES Edges of plates, where two plates “float” side-by-side, is where geologic activity takes place Plates movement is from convection currents deep in the mantle EARTH’S MAJOR PLATES: Pacific, N. American, S. American, African, Eurasian, Indian, Antarctic CONVECTION CURRENTS MOVE THE PLATES CONVECTION CURRENTS MOVE THE PLATES This continual movement (called convection currents) causes the crust to move in plate tectonics. CONVECTION CURRENTS MOVE THE PLATES Material in the mantle is heated by the radioactive core it floats to the surface next to the crust as it cools, it moves back down towards the core 7c Movement of matter among reservoirs is driven by Earth’s internal and external sources of energy PLATE BOUNDARIES Divergent boundaries plates move apart Convergent boundaries plates move together Transform boundaries plates slide past DIVERGENT BOUNDARIES Make new crust When two plates move apart and magma surfaces forming NEW crust (usually oceanic) • continental rift zones (landmass splits into two or more segments) • mid-ocean ridges (sea-floor is elevated) DIVERGENT BOUNDARIES Make new crust Rift valley continent-continent DIVERGENT BOUNDARIES Make new crust: Sea Floor Spreading Youngest rocks form at ridge Older rocks are further from ridge Oldest rocks are located at subduction zones DIVERGENT BOUNDARIES Make new crust: Sea Floor Spreading Every ~20,000 years the polarity of the Earth changes. This is change is reflected in the rocks, whose polarity is fixed once the magma is cooled. As magma rises and cools, iron and magnesium minerals align themselves to the Earth’s magnetic field “Magnetic Stripes” are formed The Earth’s magnetic field reverses polarity Magnetic stripes are mirrored on each side of the mid-ocean ridge CONVERGENT BOUNDARIES plates colliding Destroys old crust and forms new mountains Three types of convergent boundaries CONVERGENT BOUNDARIES plates colliding Continent-continent convergence: Folded mountains Ex Himalayas Eurasian/Indian plates CONVERGENT BOUNDARIES plates colliding: Subduction Zones Subduction Zones: where ocean plates slide under another plate Creates magma which moves upward, pushing up the land above it. Magma/lava solidifies into intrusive/extrusive igneous rock Heat from the magma can change the rock around it. Rock that recrystallizes without melting becomes metamorphic rock.. Denser oceanic plates always subduct beneath less dense continental plates CONVERGENT BOUNDARIES plates colliding Ocean-continent convergence: Trench & Coastal Volcanoes Andes Mountains Nazca & S.American plates CONVERGENT BOUNDARIES plates colliding Ocean-ocean convergence: Trench & Island arc TRANSFORM BOUNDARIES When two plates slide past each other no tearing or crushing - no damage occurs to the lithosphere Faults –San Andreas Fault Cause most earthquake damage Summary of Plate Movements Convection currents