Geologic processes
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Geologic Processes. Geological Processes. Tectonics Rocks bend and break (folding and faulting). Volcanism Rocks melt and explode. Erosion and surface processes Surfaces flatten out: mountains crumble and holes are filled in. Mass wasting (gravity action) Wind action Water action

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Geologic Processes

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Geologic Processes


Geological Processes

  • Tectonics

    • Rocks bend and break (folding and faulting).

  • Volcanism

    • Rocks melt and explode.

  • Erosion and surface processes

    • Surfaces flatten out: mountains crumble and holes are filled in.

      • Mass wasting (gravity action)

      • Wind action

      • Water action

  • Impact Cratering (external)

    • Bodies from space hit the ground, making a hole.


Tectonics -Folding

  • When rocks are squashed they will compress and bend away from the direction of maximum pressure


Folding in the Andes Mtn.s, S. America


Wrinkle Ridges on the Moon

  • Cooling rocks contract, the shrinkage causes folding and ridges form


Ridges on Europa


Tectonics -Faulting

  • Extension Faults -crust moves apart, makes a larger area.

  • Compression Faults -crust moves together, makes smaller area.

  • Strike-slip Faults

    -crust moves sideways,

    no gain or loss of area


Volcanism

Rocks melt and explode


Generic Volcano Structure


Volcanic Processes

  • Rocks melt and explode.

  • 2 components: lava, gasses

  • Lavas - variable viscosity,depending on chemistry

  • Low viscosity range of viscosity High viscosity

    (runny lava) (gooey, sticky lava)

    Low gas content High gas

    Result: Result:

    Low broad shapes range of volcanoes Tall cone shapes

    Volcanic Shield Cinder Stratovolcanoes Floods Volcanoes cones


Volcanic Floods -VERY low Viscosity


Hawaiian Effusive eruption


Shield Volcano


Shield Volcano’s Cauldera


Olympus MonsMartian Shield Volcano

  • Note the broad shield shape and the central cauldera


Cinder Cones- SP Crater, Arizona


Cinder Cones- SP Crater, Arizona


Stratovolcanoes


Mayon Stratovolcano, Phillipines


Mt St Helenspre-1980 eruption 1986 eruption


Mt St Helens

More tytpical eruption Oct 1st & 5th 2004


  • Many cities are built below stratovolcanoes

    e.g Seattle and Mt Rainier


  • This eruption from Mt Etna in 1983 shows lava flows engulfing the tourist facility.


Soufrière Hills, Monserrat 1995

Southern half of island evacuated and capital city lost


Alternative Materials: Carbonatites


  • Alternative Materials: Sulfur

  • Spacecraft observe live sulfur volcanoes on Io


Erosion and Surface Processes

  • Surfaces flatten out: mountains crumble and holes are filled in. The processes that carry out erosion each show characteristic patterns:

  • Mass wasting (gravity action)- land slides

  • Wind action- sand dunes, wind streaks

  • Water action- river channels, ocean shores, glacial erosion


Mass Wasting on the Asteroid Eros


Sand Dunes in the Sahara

(imaged by the Space Shuttle)


Sand Dunes in the Namib

(imaged by the Space Shuttle)


Sand Dunes on Mars


Sand Dunes on Mars


Wind Streaks on Venus


Water Channels on Mars


Water Channels on Mars


Cape Cod, Earth

  • Material is carried to the oceans and dumped.

  • Gains are ground up by pounding waves.

  • THIS IS UNIQUE TO EARTH


Impact Cratering

  • Bodies from space hit the ground, making a hole.

    (the only external process -it comes to the planet from the outside)

  • The size of the hole depends on the energy of the impact.

    • A small, slow-moving, ice-ball makes a small hole.

    • A massive, fast moving, rock makes a large hole.


Imbrium Basin

Moon


Valhalla Crater,

Callisto

Largest crater in the Solar System


Increasing Size: Increasing Complexity

Complex Craters

Simple Crater

Simple Peak Peak-Ring Multi-Ring

  • Small craters are simple bowl shapes

  • Increasing impact energy creates larger holes and more ripple shapes called complex craters


Crater Dating

  • Solar System debris falls onto planets at a regular rate, making craters.

  • The number of holes on a surface is a measure of how long it has been exposed to impacts.

  • Impact craters can be destroyed by the three internal processes (tectonics, volcanism, erosion)

  • Surfaces with few craters have active processes destroying the craters. (called YOUNG surfaces)

  • Surfaces with lots of craters have no active processes & are undisturbed. (OLD surfaces)


Young v.s Old


Active v.s Inactive


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