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Geologic Features of Mars

Geologic Features of Mars. Lab 7. Crustal Dichotomy of Mars. Striking difference between northern and southern hemispheres Southern hemisphere is 5 km higher than northern, is 70 km thick Southern hemisphere has lots of craters of all sizes

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Geologic Features of Mars

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  1. Geologic Features of Mars Lab 7

  2. Crustal Dichotomy of Mars • Striking difference between northern and southern hemispheres • Southern hemisphere is 5 km higher than northern, is 70 km thick • Southern hemisphere has lots of craters of all sizes • Northern hemisphere is lower than southern, is smooth and has been resurfaced by some process that eradicated craters and is 40 km thick

  3. Main Processes of Crust Formation • Erosion • Volcanism • Impact craters • Tectonism

  4. Erosion • Current and dominant process • Mass movement • Landslides • Sinking • Aeolian • Dunes • Windstreaks – downwind from a crater by deposition or erosion • Water • Valleys – Valles Marineris (LA→NY), maybe a rift valley(crust breaks apart along a fault line)

  5. Volcanism • Mars has largest volcanoes of solar system • Olympus Mons – huge volcano bigger than Hawaii, one of 4 in Tharsis • Volcanism produced • Lava flows • Shield volcanoes • Calderas

  6. Volcanism contd • Shield volcanoes have a steep cliff wall called a scarp • They also have a caldera • the largest and most explosive volcanic eruptions eject tens to hundreds of cubic kilometers of magma. When such a large volume of magma is removed from beneath a volcano, the ground subsides or collapses into the emptied space, to form a huge depression called a caldera

  7. Kilauea Caldera, Hawaii

  8. Impact Craters • Produced by comets and asteroids • Tapered off ~3.8 billion years ago • Older surfaces have more craters • Older craters are larger • Older craters are more eroded • Can guess age by superposition and crosscutting

  9. Tectonism • Mars has only 1 tectonic plate (Earth has 7) • Tectonic stress leads to subsurface uplift • Extensional stress led to valley formation • Valles Marineris is longest canyon in solar system

  10. Tectonic Plates of Earth http://geology.er.usgs.gov/eastern/plates.html

  11. Magnetic Field of Mars • No planetwide field • Some weakly magnetized regions in old southern highlands • Martian core has S in addition to Fe • Molten S core does not produce electrical currents, so no planetwide magnetic field

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