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Introduction to Physical Geology

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Title: Introduction to Physical Geology


1
Lecture 2 Introduction to Physical Geology
2
Lecture Outline
Physical Geology
I Geological Paradigms II Origins A) The Solar
System B) The Earth III Fundamental Concepts of
Physical Geology A) Geologic Time B) The
Earth's Structure i. Earth's
Layers ii. Plate Tectonics - From
Continental Drift to Plate Tectonics - Lithosp
heric Plates - Plate Boundaries C) The Rock
Cycle IV Planetary Geology V Conclusions
3
Geological Paradigms
Physical Geology
paradigm, n a collection of beliefs shared by
scientists a set of agreements about how
problems are to be understood
James Ussher (1581-1656) catastrophism
James Hutton (1726-1797) uniformitarianism rock
cycle
Charles Lyell (1797-1875) geologic time
Alfred Wegener (1880-1930) continental drift
4
Origin of the Solar SystemThe Nebular Hypothesis
Physical Geology
Palomar Observatory
5
Origin of the Solar SystemThe Nebular Hypothesis
Physical Geology
6
Origin of the Solar SystemThe Nebular Hypothesis
Physical Geology
gravity
physical collision
clumps of dust grains (cm)
Planetesimals (km)
planetesimals (10-100 km)
protoplanet (100-1000km)
7
The Solar SystemWhat is a Planet?
Physical Geology
(1) A planet1 is a celestial body that (a) is
in orbit around the Sun, (b) has sufficient mass
for its self-gravity to overcome rigid body
forces so that it assumes a hydrostatic
equilibrium (nearly round) shape, and (c) has
cleared the neighbourhood around its orbit. (2)
A dwarf planet is a celestial body that (a) is
in orbit around the Sun, (b) has sufficient mass
for its self-gravity to overcome rigid body
forces so that it assumes a hydrostatic
equilibrium (nearly round) shape2 , (c) has not
cleared the neighbourhood around its orbit, and
(d) is not a satellite. (3) All other objects3
except satellites orbiting the Sun shall be
referred to collectively as Small Solar-System
Bodies.
8
Origin of the EarthGeological Differentiation
Physical Geology
  • Earth melted by
  • gravitational energy left from formation of
    planet
  • meteor bombardment
  • radioactive decay
  • Gravity concentrated denser materials (Ni Fe)
    in center
  • Less dense materials (silicates) forced to outer
    layers
  • Crust became stable after 1 billion years
  • Compositional Zones
  • Crust
  • Continental
  • Oceanic
  • Mantle
  • Core
  • Outer (Liquid)
  • Inner (Solid)

9
Fundamental ConceptsEarth's Layers
Physical Geology
  • Compositional Zones
  • Core
  • Solid inner core
  • Liquid outer core
  • Radius of 3500 km
  • 16.2 of Earth's vol.
  • 31.5 of Earth's mass
  • Generates Earth's magnetic field
  • Mantle
  • Thickness 2900 km
  • 82.3 of Earth's vol.
  • 67.8 of Earth's mass
  • Crust
  • Oceanic 4-20km thick
  • Continental 30-70km thick
  • Mechanical Zones
  • Core
  • Mesosphere
  • Lower mantle
  • Rigid
  • Very Hot
  • Capable of gradual flow
  • Asthenosphere
  • "weak" layer
  • Convecting mantle
  • Soft and readily flows
  • Lithosphere
  • Crust and Upper Mantle
  • Rigid
  • Brittle

10
Fundamental ConceptsGeologic Time
Physical Geology
  • Phanerozoic Eon -"Eon of Evident Life"
  • Paleozoic Era -"Era of Old Life"
  • Mesozoic Era -"Era of Middle Life"
  • Cenozoic Era -"Era of Modern Life"

Divisions Eon Era Period Epoch Age
11
Fundamental ConceptsPlate Tectonics - The
Evidence
Physical Geology
12
Fundamental ConceptsPlate Tectonics - The Ocean
Floor
Physical Geology
Mid-Ocean Ridge System
13
Fundamental ConceptsPlate Tectonics - The Ocean
Floor
Physical Geology
Mid-Ocean Ridge System
  • underwater mountain range
  • 80,000 km long
  • 1500-2500 km wide
  • up to 3000 m above sea floor
  • rift valley, 1-2 km deep, runs along axis
  • 4000 km wide fracture systems

14
Fundamental ConceptsPlate Tectonics - The Ocean
Floor
Physical Geology
magnetic striping
crustal age
15
Fundamental ConceptsPlate Tectonics - The Ocean
Floor
Physical Geology
16
Fundamental ConceptsPlate Tectonics - The Engine
Physical Geology
17
Fundamental ConceptsPlate Tectonics -
Lithospheric Plates
Physical Geology
18
Fundamental ConceptsPlate Tectonics Plate
Boundaries
Physical Geology
19
Fundamental ConceptsThe Rock Cycle
Physical Geology
  • Atmospheric Processes
  • Weathering
  • Physical Weathering
  • Chemical Weathering
  • Biological Weathering
  • Sediment Transport
  • Lithospheric Processes
  • Burial
  • Compaction and Cementation
  • Heat and Pressure
  • Stress
  • Plate Tectonics
  • Exposure

20
Planetary Geology
Physical Geology
Venus
Jupiter
Europa
Magellan
Galileo
Io
Mars
Galileo
Viking 1
Voyager 1
21
Planetary GeologyMars
Physical Geology
Physical Geology
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