Transcript Powerpoint

Lecture 2
Introduction to Physical Geology
Physical Geology
Lecture Outline
I
II
Geological Paradigms
Origins
III
Fundamental Concepts of Physical Geology
IV
V
A)
B)
The Solar System
The Earth
A)
B)
Geologic Time
The Earth's Structure
C)
i.
ii.
Earth's Layers
Plate Tectonics
-
From Continental Drift to Plate Tectonics
Lithospheric Plates
Plate Boundaries
The Rock Cycle
Planetary Geology
Conclusions
Physical Geology
Geological Paradigms
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
Palomar Observatory
Physical Geology
Origin of the Solar System
The Nebular Hypothesis
Physical Geology
Origin of the Solar System
The Nebular Hypothesis
painting by W illiam K. H artmann
Physical Geology
Origin of the Solar System
The Nebular Hypothesis
gravity
physical
collision
clumps of dust grains
(cm)
Planetesimals
(km)
planetesimals
(10-100 km)
protoplanet
(100-1000km)
Physical Geology
The Solar System
What is a Planet?
(1) A “planet”1 is a celestial body that (a) is in orbit
around the Sun, (b) has sufficient mass for its selfgravity 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 selfgravity 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”.
Physical Geology
Origin of the Earth
Geological Differentiation
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)
Physical Geology
Fundamental Concepts
Earth's Layers
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
Physical Geology
Fundamental Concepts
Geologic Time
Divisions
Eon
Era
Period
Epoch
Age
Phanerozoic Eon
Paleozoic Era
Mesozoic Era
Cenozoic Era
-"Eon of Evident Life"
-"Era of Old Life"
-"Era of Middle Life"
-"Era of Modern Life"
Physical Geology
Fundamental Concepts
Plate Tectonics - The Evidence
Physical Geology
Fundamental Concepts
Plate Tectonics - The Ocean Floor
Mid-Ocean Ridge System
Physical Geology
Fundamental Concepts
Plate Tectonics - The Ocean Floor
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
Physical Geology
Fundamental Concepts
Plate Tectonics - The Ocean Floor
magnetic striping
crustal age
Physical Geology
Fundamental Concepts
Plate Tectonics - The Ocean Floor
Physical Geology
Fundamental Concepts
Plate Tectonics - The Engine
Physical Geology
Fundamental Concepts
Plate Tectonics - Lithospheric Plates
Physical Geology
Fundamental Concepts
Plate Tectonics – Plate Boundaries
Physical Geology
Fundamental Concepts
The Rock Cycle
Atmospheric Processes
Weathering
Physical Weathering
Chemical Weathering
Biological Weathering
Sediment Transport
Lithospheric Processes
Burial
Compaction and Cementation
Heat and Pressure
Stress
Plate Tectonics
Exposure
Physical Geology
Planetary Geology
Venus
Europa
Jupiter
Magellan
Galileo
Mars
Io
Galileo
Viking 1
Voyager 1
Physical Geology
Planetary Geology
Mars