The Earths Interior

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The Earths Interior
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Earth Facts
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Happy the man whose lot it is to knowthe secrets
of the earth. He hastens notto work his fellows'
hurt by unjust deeds,but with rapt admiration
contemplateimmortal Nature's ageless
harmony,and how and when her order came to
be.Such spirits have no place for thoughts of
shame. - Euripides (484-406 B.C.)
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Inside the Earth
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Crust

• The exterior portion of the earth
• Lies above the Moho discontinuity

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Crust

• 3 types of solid rock igneous, sedimentary,
  metamorphic
• Oxygen silicon
• Oceanic crust 8 km thick basalt
• Continental crust 32km thick granite basalt

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Elements in the Crust
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• Oxygen 46.6
• Silicon 27.72
• Aluminum 8.13
• Iron 5.00
• Calcium 3.63
• Sodium 2.83
• Potassium 2.59
• Magnesium 2.09
• Titanium 0.40
• Hydrogen 0.14
  

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Mantle

• Layer between the crust and the core
• Silicon, oxygen, iron magnesium
• 870-2200c
• 2900 km thick

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Lithosphere

• Thin outer shell of the earth
• Consisting of the crust and the rigid upper mantle

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Lithosphere

• Rigid layer
• Broken up into 7 major lithospheric plates

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Asthenosphere

• Zone of the mantle beneath the lithosphere
• Consists of slowly flowing solid rock
• Plasticity when solid rock flows

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Moho

• The Mohorovicic discontinuity
• Croatian scientist found increased speed of
  seismic waves
• Boundary between the mantle and the earths crust
• Reveals increase in density

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Seismic Waves
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Shadow Zones

• Location on the earths surface where no seismic
  waves or only P waves can be detected.

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Core

• Central portion of earth
• Below the mantle
• Depth of about 2,900 kilometers (1,800 miles)
• Consisting of iron and nickel
• Liquid outer core and a solid inner core

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Magnetosphere
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Magnetosphere

• Region of space that is affected by the Earths
  magnetic field

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The Dynamic EarthPlate Tectonics

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Theory of Continental Drift

• 1900s Alfred Wegener proposed that the earth
  used to be one giant landmass that split to form
  todays continents

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Continental Drift

• Pangaea
• all lands
• a single landmass
• origin of all the continents

• Panthalassa
• all seas
• giant ocean that must have surrounded Pangaea.

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Wegener's Evidence for Continental Drift

• The shape of continents suggests they once fit
  together
• Noticed first in 1858 as soon as good maps were
  being made

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Wegener's Evidence for Continental Drift

• Fossils The glossopterus flora and fauna are
  now found in widely separated continents in the
  southern Hemisphere.

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Fossil Evidence

• Fossils support Wegeners theory
• Glossopteris
• Mesosaurus
• Lystrosaurus
• Cynognathus

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Wegener's Evidence for Continental Drift

• Paleoclimate evidence
• Distribution of Paleozoic
• Coral reefs
• Coal beds
• Deserts
• 250-300 million years ago

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Wegener's Evidence for Continental Drift

• Rock types and mountain ranges can be traced
  across now widely separated continents.

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Rock Evidence

• Glacial deposits
• Folded mountains
• Coal deposits

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Wegener's Evidence for Continental Drift

• Evidence of ancient glaciers in all of the
  southern continents
• Do you think all of this satisfied the critics?

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Where is the Force?

• What makes the plates move?
• The answer is on the ocean floor

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Mid-ocean Ridge

• System of undersea mountain ranges
• Wind around the earth
• 65,000 km
• Ocean rocks much younger than continental rocks

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Mid-Atlantic Ridge

• Undersea mountain range
• Steep, narrow valley down the center 

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Seafloor Spreading

• Movement of the ocean floor away from either side
  of a mid-ocean ridge
• Caused by convection currents

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Seafloor Spreading
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Convection Cells
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Uneven heating causes movement in fluids
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Paleomagnetism of the Ocean Floor

• Magnetic fossil record of the alternating
  magnetic field of the ocean floor.

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Plate Tectonics

• Theory that the lithosphere is made up of plates
  that float on the asthenosphere
• Plates possibly moved by convection currents

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Types of Crust

• Oceanic crust
• Material that makes up the ocean floor
• Continental crust
• Material that makes up landmasses

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Divergent Boundary

• Formed by two lithospheric plates that are moving
  apart

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Rift Valley

• Steep, narrow valley
• Formed as lithospheric plates separate

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Convergent Boundary

• Border formed by the collision of two
  lithospheric plates

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Continental vs. Continental
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Oceanic vs Continental
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Subduction Zone

• Region where one lithospheric plate moves under
  another.

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Ocean Trench

• Formed when one oceanic crust is subducted under
  another oceanic crust

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Oceanic vs Oceanic
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Island arc

• Chain of volcanic islands
• Formed by subduction at ocean trenches

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Transform Fault Boundary

• Formed by two lithospheric plates that slide past
  each other

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Theory of Suspect Terrains

• theory that continents are a patchwork of
  pieces of land that have individual geologic
  histories

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• The earth was made so various,that the mind of
  solitary man,
• studious of changeand pleased with novelty,
• might be indulged.
• - Cowper, English poet

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Crust

• Asthenosphere
• Lithosphere

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Continental Drift

• Hypothesis stating that the continents once
  formed a single landmass
• Broke up and drifted to their present location

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The Earths Interior