HNRS 228 Astrobiology Chap'4 Geology Bennett et al'

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HNRS 228 AstrobiologyChap.4 Geology Bennett et
al.

• Lecture Notes for Chapter 4
• (mostly from HNRS 227)
• Prof. Geller

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The Geological History

• Reading the Earths history in the rocks
• Rocks and fossils
• Relative and absolute dating methods
• Formation of the Earth
• Accretion, differentiation, Moon, age
• The Hadean Earth
• Plate Tectonics
• Climate
• Geology and life

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Telling Rocks Apart

• How geologists tell apart different minerals and
  rocks
• color, luster, texture
• hardness test
• scratching one against another
• diamond is hardest
• acid test
• using weak hydrochloric acid to
• streak test
• form a streak across a ceramic tile

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Minerals(see Table 19.1)

• Characteristics
• naturally occurring
• inorganic
• definite crystalline structure
• The natural resources of industry

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Igneous Rocks

• Rocks formed from hot molten mass of melted rock
  material

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Sedimentary Rocks

• Rocks formed from particles or dissolved
  materials from previously existing rocks.

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Metamorphic Rocks

• Previously existing rocks that have been changed
  by heat, pressure, or hot solutions into a
  distinctly different rock.

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The Rock Cycle
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Earths Interior andHow We Know It
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Earthquakes Galore
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Earths Inside Story
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Crustal Rumblings
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Plate Tectonics

• The theory that the Earths crust is made of
  rigid plates that float on the asthenosphere.
• Consider the scientific evidence for plate
  tectonics and what forced scientists to accept
  the theory as fact

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Fossils across an ocean
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Boundaries Galore
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Plates are smashing
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Surface Building Processes

• Stress
• stress is a force that tends to compress, pull
  apart, or deform
• different types of stress
• compressive stress
• tensional stress
• shear stress
• Strain
• the adjustment to stress

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Stress and Strain
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Surface Building Processes

• Folds
• bends in layered bedrock
• Anticline /\
• Syncline \/

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Surface Building Processes

• Faulting
• formation of a crack caused by relative movement
  of rock on either side of a fracture
• different types - normal, reverse, thrust

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Earthquakes

• Defined as quaking, shaking, vibrating, or
  upheaval of the ground
• Earthquake causes
• elastic rebound theory
• Intensity measure
• Richter Magnitude
• not linear

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Mountains

• elevated parts of the Earths crust that rise
  abruptly above the surrounding surface
• Causes
• folding, faulting, volcanic activity

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Volcanoes

• hill or mountain formed by the extrusion of lava
  or rock fragments from magma below
• Different types
• shield, cinder cone, composite (composite shown)

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Tear-Down Processes

• Weathering
• mechanical weathering
• chemical weathering
• Erosion
• mass movement (mass wasting)
• running water (floodplain, delta)
• glacier
• wind (deflation and abrasion)
• impact cratering

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Development of Geologic Time

• Fossilization
• Reading the Rocks
• principle of uniformity
• principle of original horizontality
• principle of superposition
• principle of crosscutting relationships
• principle of faunal succession
• radiometric dating
• Geologic Time Scale

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Geologic Time Scale