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Class 2a: Landforms or What goes up must come down

Class 2a: Landforms or What goes up must come down. Today’s class. "The summit of Mt. Everest is marine limestone." Tectonic forces Earthquakes, volcanoes Diastrophism Gradational processes Weathering, mass wasting Erosion/deposition: water, waves, wind Examples from CA, SW Asia, Oceania.

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Class 2a: Landforms or What goes up must come down

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  1. Class 2a: LandformsorWhat goes up must come down

  2. Today’s class • "The summit of Mt. Everest is marine limestone." • Tectonic forces • Earthquakes, volcanoes • Diastrophism • Gradational processes • Weathering, mass wasting • Erosion/deposition: water, waves, wind • Examples from CA, SW Asia, Oceania

  3. Rock cycle • Your responsibility! • Differences between igneous, sedimentary, metamorphic • Examples of each

  4. Plate tectonics • Theorized in 1912; proven after WWII • 12 large plates (lithosphere) float on liquid rock (asthenosphere) • 200 million years ago, all one continent (Pangaea)

  5. Plate tectonics • Divergent boundaries • Generally mid-ocean • Underwater volcanoes, few quakes • Convergent boundaries • Usually near continental edges • Violent volcanoes near ocean, strong quakes • Transform boundaries • No volcanoes, mild to strong quakes

  6. Earthquakes • Stress relief via crust movement • 500,000 per year; 800 felt • Seismic waves of energy • P-waves or primary waves (Slinky) • S-waves or secondary waves (up and down) • Earthquakes don't kill people, buildings (and gas mains) do

  7. Diastrophism • Your responsibility! • Folding vs. faulting • Escarpment, rift valley, fault-block mountain (Sierra Nevada)

  8. Volcanism • Pressure on molten rock • Composite volcanoes • Violent and explosive • Along subduction zones • Relatively hard to predict • Shield volcanoes • More calm and constant • Along divergent boundaries or at hot spots • Relatively less dangerous

  9. Gradational processes • Weathering • Chemical vs. physical • Mass movement • Erosion/deposition • Water (rivers, oceans) • Ice (glaciers) • Wind

  10. Weathering • Most mountains are going down faster than they’re going up • Mechanical weathering breaks rocks into smaller pieces • Frost action • Salt crystals • Roots • Exfoliation • Rock chemistry does not change

  11. Weathering • Chemical weathering changes the chemistry of rocks • Oxidation (exposure to oxygen) • Hydrolysis (exposure to water) • Carbonation (exposure to carbon dioxide) • Warmth and water encourage chemical reactions • Weathering loosens rock particles, creates soil

  12. Erosion and deposition • Erosion carries particles away • Deposition deposits them • Running water • Constant water, floods • Most important landform agent in deserts • Floodplains, levees, and deltas • Arroyos and alluvial fans

  13. Glaciers • Rivers of ice • Carve out landforms from mountains • Glacial troughs • Fjords • Cirques • And deposit material when they leave • Outwash plain • Moraines

  14. Waves and coastlines • Waves transfer energy, don’t move water • Energy moves particles down the coast (longshore current) • Newer coastline=erosion • Older coastline=deposition • Barrier reef: only organically formed landform

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