Intro to Geology

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Intro to Geology

• EARTHS CRUST
• and
• INTERIOR

Summer 2008
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Earth

• 4.55 Billion years old
• Average diameter 12,742 km

You are here
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a still-active planet
significant heat-driven motions above and below
the surface

• a long inactive moon

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Lecture 1 Density and Gravity

• MOUNTAINS A VIRTUAL TOUR

• A geologists view of mountains

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Purpose

• to explain Earths surface form
• to teach scientific method and logic

• physical geology
• rocks and minerals

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Sugarloaf Peak, Box Springs Mountains

• an ancient magma chamber

molten rock reservoir beneath a volcano i.e. must
have solidified and been uplifted many kilometers
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Sierra Nevada and Owens Valley

• a chain of ancient magma chambers

originally below a line of volcanoes like the
Cascade Range i.e. volcanoes can be turned off
and worn off the face of Earth
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Hawaiian Islands
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Hawaii cont
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Mt. Ruapehu
1995
Ruapehu
Ngauruhoe
eruptions not always good for conical shape
Tongariro

• active volcanoes in a line

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Mt. St. Helens, WA
May 17, 1980
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Mt. Ngauruhoe, New Zealand
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Mt. Ngauruhoe, New Zealand
i.e. young, not yet worn away active?
dormant?
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Mt. Doom, Mordor

• volcano with conical shape

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Other Volcano Shapes
small dome of viscous lava
Hawaii
huge flat shield volcano
Puu Heewa
explosions build cones lava builds shields and
domes
tiny cinder cones
fluid lava flow

• Shape is a clue to eruptive style

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There are chains of volcanoes on the ocean floor
too!
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Marble Mountains, Mojave Desert (old Route 66)

• ancient sea-floor deposits, resting on rocks of
  ancient magma chamber

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Marble Mountains, Mojave Desert (old Route 66)

• ancient sea-floor deposits, resting on rocks of
  ancient magma chamber

i.e. oceans may expand and contract ocean
floor may be tilted and uplifted onto continent
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The French Alps

• more layered oceanic sediment

i.e. many mountains are constructed from ocean
floors
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Mt Everest, Himalaya Mountains

• more layered oceanic rocks

i.e. uplift may reach nearly 9 kilometers above
sea level
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Monument Valley, Arizona/Utah

• horizontal layered sediments

i.e. requires huge volumes to be worn away
(eroded) requires long-term stability
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The white cliffs of Dover
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Just a Place to Ski and Climb?
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The Steinplatte, Austria

• An exhumed coral reef

i.e. sea floor was uplifted, then the soft
mud-rocks around the reef were worn away
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Glacier National Park

• a pyramidal peak or horn

faces of peak carved by ice of glaciers flowing
by i.e. evidence of recent climate
change
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Patterns for mountain formation?

• observations mountains form
• at volcanoes (on land and at sea)
• from the uplifted roots of volcanoes
• by pushing rocks up above sea level
• by folding/compressing rocks
• by erosion of soft rocks by rivers
• by erosion of hard rocks by glaciers

heat from below
tectonics
surface processes

• these factors are interrelated, as we shall see

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Next up
Earths Crust and Interior

• Density