Home

Links

 3. Solar System Intro

4. Solar System Origin

5,6, 7. Plate Tectonics

 8. Matter and Minerals
   

 9. Igneous Rocks
  10.Volcanos    

 Physical Geology Lecture Outlines 1

Lecture 1- Class logistics. All the relevant information is in the Class Home Page.

Lecture 2- Introduction to Earth Systems
Reading: Chapter 1, Tarnuck and Lutgens
Topics:
1. Earth systems
2. Internal structure of the earth
3. Plate Tectonics
4. The Rock Cycle
5. Geologic Time
1. Earth is a Dynamic Planet (in contrast to the moon for example).
The surface is constantly changing driven by:
a. The internal heat engine which causes:
Plate motions (Earthquakes)
Volcanoes
b. The external heat engine (the sun)
Atmospheric circulation
Oceanic circulation
Hydrologic cycle
 
2. Earth System
Components (inside out)

 
Core (Metal)  
Mantle (Dense rock) 
 
Lithosphere (Less dense rock)  Biosphere (Life )
 Hydrosphere (Water)
Atmosphere (Air)

 
Main points:
Examples of Interactions:
1. Outer Core-> drives the Earth's magnetic field -> The magnetic field protects life from solar radiation, making life possible
 
2. Mantle-> convection drives lithospheric plates-> plate tectonics-> volcanoes->
gases spewed into atmosphere-> composition of atmosphere determines what life-forms can exist
 
3. Algae die on a continental shelf-> buried in a sedimentary basin -> algae turn to oil-> Oil is pumped out -> gasoline burns in a car->Carbon dioxide gas returns to the atmosphere -> solar radiation retained -> climate warms -> glaciers melt ->Sea level goes up -> continental margins flood -> the State of florida disappears -> it becomes a nice place for more algae to live
 
3. Internal structure of the earth
What is the size of the earth?
radius=6380 km
1/2 of this thickness (~ 3000 km) is the core composed of:

The other 1/2 is the mantle made of dense rock on which the less dense lithosphere is floating.

How thick is the lithosphere? (In other words how thick are the plates)?
Only 0 to 200 km (average for continental plates is about 100 km)
So the thickest plates are only 3% of the radius of the earth: Less than the skin of an orange.
4. Plate Tectonics
The scientific theory that explains much of geology.
Before plate tectonics: many disconnected explanations for geological phenoma.
Now: a unifying theory that links all parts of geology.
Basic components:
5. The Rock Cycle
Rock= Naturally occurring aggregate of minerals
Three main types of rock:
 
The rock cycle relates these three types of rock.
Example:
1. Lava pours out of a volcano and cools -> basalt (igneous rock)
2. Weathering and erosion break down this rock into sand
3. Sand transported to ocean by a river
4. Sand is buried by more sand and turns into a sandstone (sedimentary rock)
5. Sandstone is dragged down into a subduction zone
6. Turns into a quartzite (metamorphic rock)
7. Quartzite is melted, mixed with other magma
8. New lava pours out of volcano (igneous rock again)
 
6. Geologic Time
Deep time: peculiar to geology and astronomy
Human history -- less than 10,000 years
Modern humans -- about 100,000 of years?
Hominids -- about 2.5 million years
The Earth is about 4,540,000,000 years (4.5 billion years)
 
Human history is less than 0.0002% of Earth history
If earth history lasted 1 year Hominids would appear on Dec. 31 at about 7 PM.
Human history would take place during the last 80 seconds before midnight.
 
Geologic Time Scale
Look at the book.
Learn the time scale to the level of Eons and Eras (including the age of the boundaries)
Familiarize yourself with the Periods.
 
 
 
Lecture 3- Introduction to the Solar System
Reading: Overview of the Solar System and Chapter 22 of Tarbuck and Lutgens
 
Topics:
1. Review of Physical Principles
  • Matter and Energy
  • Gravity
  • Kinetic Energy
  • Heat
  • Centrifugal Force
  • Conservation of Energy
  • Conservation of Angular Momentum
2. Nuclear Synthesis
3. Overview of the Solar System
 
1. Review of Physical Principles
 
Matter and Energy make up the physical universe
Matter:
"Everything is made of atoms - particles that are in perpetual motion, repelling each other when they are close together, and attracting each other when they are far". R. Feynman
 
Matter has Mass
 
Energy:
Hard to define, takes many forms, it is always changing:
Light, heat, movement, electricity, etc.
Causes something to happen
 
Matter and Energy are two expressions of the same thing:
Einstein's famous equation:
E=mc^2
Energy is equal to the mass times the speed of light times the speed of light.
Gravity
One of the more mysterious properties of matter.
Gravity shapes the universe.
All bodies attract each other.
Newton's Law:
F= G mM/r^2
 
How would you calculate F due to gravity acting on you right now?
 
Acts over enormous distances
At the atomic scale- very weak
For two electrons if:
Gravity=1
Electrical force= 4 x 10^42 (4 followed by 42 zeroes)
 
Kinetic Energy
Energy of motion
KE= 1/2 mv^2
The faster it moves, the more energy it has.
 
Heat
Energy of motion at the molecular scale
Molecules vibrating fast- hot
Molecules vibrating slowly- cold
Gases
expand and cool
contracts and heats up
 
Conservation of Energy
Energy (mass) is conserved in any event.
Energy changes form, but the total amount remains constant
Examples:
A car: Chemical energy stored in gasoline turns to motion, noise, heat, aggravation, etc.
Hit a nail with a hammer, where does the energy go?
Touch the nail after hitting it a few times. You'll find out where the energy went!
 
Centrifugal Force
A ball swung at the end of a string wants to fly away.
Which way will it go if you let go?
What keeps the planets from flying out into space?
What keeps the planets from falling into the sun?
 
Conservation of Angular momentum
Consider a spinning disk:
-All parts of the disk have kinetic energy
-The outside of the disk has greater linear velocity (more kinetic energy) than the inside
-If you bring in some mass from the outside of the disk while it is rotating , the whole thing will speed up in order to conserve the total kinetic energy.
Examples: skaters, dancers, kids in swings
 
2. Nuclear Synthesis
Most of the universe is Hydrogen and Helium
 Plot showing the relative abundance of elements in the sun. Notice that the vertical scale is logarithmic: each unit represents a ten times increment. Elements with odd atomic numbers are less abundant because their nuclei are less stable.
 
All other elements are made from H and He inside stars during nuclear synthesis
A series of reactions take place at progressively higher temperature
   Temperature  Process  Products
 Hydrogen-burning  20 million degrees  H nuclei combine  Helium
 Helium-burning  200 million deg.  He nuclei combine  Carbon and Oxygen
 Carbon and Oxygen burning  500 million degrees  C and O nuclei combine  Silicon and others
 Silicon-burning  2 billion degrees  Si nuclei combine  Calcium and others
 equilibrium-burning  4 billion degrees

 Random reconfiguration to achieve most stable elements
 Iron and others
 
Young stars (like the sun) make only light elements
Cross-section through a mature star showing how increasingly heavier elements are produced by nuclear synthesis in the interior of the star.
Elements heavier than iron (Fe) are rarely produced, they require a different process (neutron bombardment)
The fact that heavy elements are present on Earth means that the that makes the solar system are remnats an ancient big star (or stars).
Lecture 4- Origin of the Solar System
Reading: Origin of the Solar System
 
Topics:
1. Overview of the Solar System
Inner
Outer
1 star
9 planets
4 small rocky inner planets
4 big gassy outer planets plus Pluto
68 moons
A bunch of comets and asteroids
 
2. Essential Characteristics of the Solar system
 
3. Origin
Solar Nebula
Collapse
Proto-sun
Planetary Accretion
Planetary Differentiation
Solar Ignition- Loss of volatiles from Inner Solar System
Early Solar System History
 

    Comparison of the properties of the Sun and Planets

Terrestrial Planets

Jovian Planets
 Property

 Sun
  Mercury  Venus  Earth  Mars  Jupiter  Saturn  Uranus  Neptune  Pluto
 Distance 
million km

 0

 58

 108

 150
  230

 780

 1,430

 2,870

 4,500
  5,900

 Relative Distance

 0

 0.4

 0.7

 1
  1.5

 5

 10

 19

 30
  39

 Relative Mass
  343,000

 0.06

 0.8

 1
  0.11

 318

 95

 15

 17

 0.002 ?

 Radius km
  696,000

 2,440

 6,050

 6,340

 3,390
  71,400

 60,000

 25,900

 25,000
  1,900
 Density
water=1

1.4 

 5.4

 5.2

 5.5

 3.9

 1.3

 0.7

 1.2

 1.7

 >1.7

 Moons

 -

 0

 0

 1

 2

 14

 10

 5

 2

 ?

 Atmosphere
  H, He

 none
  CO2

 O2, N2
  CO2  H2, He  H2, He

 H2, He,CH4

 H2, He,CH4

 ?

 
 Comparison of the planets by size. Their distance to the sun is not to scale. From "The Inaccessible Earth" by Brown and Musset
 
Essential Characteristics of the Solar System

For a brief summary of the Solar Nebula Theory for the origin of the Solar System look at:

Origin of the Solar System

 

Lectures 5 , 6 and 7- Plate Tectonics
Reading: Chapter 2 of the textbook
 
Topics:
1. History of Science
2. Continental Drift
3. Sea Floor Spreading
4. Paleomagnetism
5. Earthquakes
6. Plate Boundaries
Divergent
Convergent
Transform
7. Hotspots
 
1. History of Science
What is Science?

• Method of inquiry aimed at understanding the world.

Scientific Method

1. Gathering facts:

– Observation/experimentation

2. Formulate a Hypothesis
3. Test the Hypothesis
4. Modify the Hypothesis until it accounts for all the observations
 

Scientific Theory

• A set of tested hypothesis
• Widely accepted (hopefully)
• Are Scientific Theories ever proven?
Not realy, they are often disproven though
• Are they ever right?
They represent the best available answer to a given question, but usually as time goes on they are frequently modified, updated or even discarded.


Scientific Progress
 Scientific progress is not linear
 "The Structure of Scientific Revolutions" by Thomas Khun (1962)

 Paradigm= dominant theory, concept, or model

Khun’s Model

• Normal Science (under a paradigm)
• Paradigm shift -> Scientific revolution
• Back to normal Science (under new paradigm)

 

 

 Role of technology in scientific revolutions

• Key in triggering scientific revolutions
• New tools allow new observations which can challenge the old paradigm

Examples

• The telescope and Galileo
• Calculus and Newton
• The sonar and marine magnetomer surveys and Plate Tectonics
 

 
2. Continental drift
• The precursor for Plate Tectonics
• Proposed by Alfred Wegener in 1915
• NOT accepted by the scientific community at the time

Evidence for continental drift
 

  • Jig-saw fit of the continents
  • Similar rocks in all southern continents
  • Paleozoic glaciation (about 300 million years old) in southern continents
  • Late Paleozoic tropical forests in northern continents
  • Same Mesozoic (250 Million years old) fossils found in southern continents
  • Link of Appalachian-Caledonian mountains across the Atlantic
  • Apparent polar wander (discovered in the 40's and 50's)
Problems with Wegener's theory:
  • • Mechanism for drift:
    – Tidal forces? Not realy strong enough
    • What to do with oceanic crust which lies between the continents:
    – Continents plow through it? Oceanic crust is actually very strong.
    • Wegener was an outsider to the geological community so people dismissed his ideas
     
 
3. Sea Floor Spreading
  • Great progress in studying the ocean floor since WWII
 


Theory proposed by Harry Hess (1960):

"I shall consider this paper an essay in geopoetry".
  • Mantle convects at 1 cm/yr (actually faster in many cases)
  • Rising convection at mid-ocean ridges (high heat, high topography)
  • Mantle material comes to the surface at ridges
  • The whole ocean is swept clean every 300 to 400 million years (actually more like 250 my)
  • Continents can rift appart to produce new mid-ocean ridges
  • Continents are carried passively
  • Their leading edges are strongly deformed against the down going limb of the convecting mantle
  • Oceanic sediments and seamounts get plastered against the continents
  • Oceaninc basins are impermanent, continents are permanent
  • The earth is a dynamic body, its surface always changing.
 
  • 4. Paleomagnetism

The Earth's core generates a magnetic field

When lavas crystallize they record the orientation of the magnetic field (like a compass)

Apparent polar wander:

  • ancient lavas do not point to present-day north
  • ancient lavas of the same age, but from different continents, point at different places

Paleomagnetism can be used to track the movement of the continents in the past

Magnetic reversals:

  • Earth's magnetic field is unstable: it periodically flips polarity
  • The sequence of reversals can be used as a dating tool
  • The ocean floor is a giant magnetic tape recorder: the history of sea floor spreading is recorded on it
  •  
5. Earthquakes
  • The plate boundaries are the locus of most earthquakes
  • Most earthquakes are shallow (less than 70 km deep)
  • At subduction zones earthquakes reach 670 km
 
6. Plate boundaries
  • Most crustal deformation takes place along plate boundaries
  • Divergent boundaries
    • Plates moving away from each other
    • Tensional or extensional deformation
    • Thinning of the lithosphere and basin formation
    • Examples;
      • mid-ocean ridges (mid-Atlantic Ridge)
      • Rifts (East Africa, Rio Grande)
       
  • Convergent boundaries
    • Plates moving towards each other
    • Compressional deformation
    • Thickenning of the lithosphere and mountain building
    • Examples:
      • Ocean-ocean: Ocenic island arcs (Japan, Aleutians)
      • Ocean-Continent: (Andes)
      • Continent-Continent collision (Himalayas, Appalachians, Urals)
       
  • Transform boundaries
    • Plates moving laterally past each other
    • Complex deformation
    • Examples:
      • Western California (San Andreas Fault)
      • Anatolian Fault (Turkey)
7. Hotspots
Lecture 8 - Matter and Minerals

Topics:

1. Intro to Minerals

2. Atoms

3. Bonding

Ionic
Covalent
Metallic
 
4. Structure of Crystals
5. Chemical composition of the Earth's crust
6. Mineral groups (composition)
7. Silicate minerals
8. Rock-forming minerals
1. Intro to Minerals

Earth made of rocks, rocks made of minerals

Mineral: Naturally occurring crystalline solid

  • Steel/Gold
  • Water/Ice
  • Glass/Quartz
  • Diamond/Graphite

Crystal: Has definite structure

  • Made of bonded atoms
 
2. Atoms
  • Chemical elements
    • Specific physical properties
    • Specific chemical properties
      • Aluminum/Iron
      • Chlorine/Argon
      • Carbon/Silicon
  • Atomic Structure
    • Nucleous
      • Protons
      • Neutrons
    • Atomic Number= number of protons
    • Atomic Mass= protons+neutrons
    • Isotopes: same element, different mass (due to diferent number of neutrons)
      • Carbon12/Carbon14
      • Some isotopes are unstable: they emit radiation and change mass
    • Electrons in orbitals (shells)
     

 Element  Symbol
Atomic
Number

 Atomic Mass

Electrons per Orbital
  Total electrons
 Hydrogen  H  1  1  1        1
 Helium  He  2  4  2        2
 Lithium  Li  3  6  2  1      3
 Beryllium  Be  4  8  2  2      4
 Boron  B  5  10  2  3      5
 Carbon  C  6  12  2  4      6
 Nitrogen  N  7  14  2  5      7
 Oxygen  O  8  16  2  6      8
 Fluorine  F  9  18  2  7      9
 Neon  Ne  10  20  2  8      10
 Sodium  Na  11  22  2  8  1    11
 Magnesium  Mg  12  24  2  8  2    12
 Aluminum  Al  13  26  2  8  3    13
 Silicon  Si  14  28  2  8  4    14
 Phosphorous  P  15  30  2  8  5    15
 Sulfur  S  16  32  2  8  6    16
 Chlorine  Cl  17  34  2  8  7    17
 And so on ....                

This sytematic arrangement of the elements leads to the Periodic Table that groups elements with similar properties together.
 
3. Bonding

4. The Structure of Crystals

5. The Chemical Composition of the Continental Crust

Eight elements make up about 99% of the weight of the continental crust
 1.  Oxygen  O  47%
 2.  Silicon  Si  28%
 3.  Aluminum  Al  8%
 4.  Iron  Fe  5%
 5.  Calcium  Ca  4%
 6.  Sodium  Na  3%
 7.  Magnesium  Mg  2%
 8.  Potassium  K  2%

6. Mineral Groups (Composition)

7. Silicate Minerals

Silicate structural classification
 Structural Type  Mineral Composition  
 Isolated tetrahedra  Olivine  (Mg,Fe)2 SiO4  
 Single Chains  Pyroxene  (Mg,Fe)SiO3  
 Double Chains  Amphibole  Ca2(Fe,Mg)5Si8O22(OH)2  
 Sheets  Mica  KAl2(AlSi3O10)(OH)2  
 3-D Frameworks  Plagioclase  (Ca,Na)AlSi3O8  
   Alkali Feldspar  KAlSi3O6  
   Quartz  SiO2  

8. Common rock-forming minerals (see list above), plus calcite.

Lecture 9 - IGNEOUS ROCKS

Outline

1. Rock Types
Igneous, Sedimentary, Metamorphic
2. The Rock Cycle and Plate Tectonics
3. Igneous Rocks
4. Classifications
Grain size
Composition
5. Magmas Processes
6. Igneous Rocks and Plate Tectonics

Rock Types

The Rock Cycle

Igneous Rocks

Naming of Igneous Rocks

Grain Size

Chemistry of Igneous Rocks

 SiO2 CONTENT  MAGMA TYPE

 VOLCANIC ROCK

 PLUTONIC ROCK
    Fine-grained  Coarse-grained
<46% Ultramafic Komatiite Peridotite
 52%-47%  Mafic  Basalt  Gabbro
 52-65%  Intermediate  Andesite  Diorite
 >65%  Felsic  Rhyolite  Granite

Igneous Rock Identification

How magma forms

How magmas evolve

INTRUSIVE STRUCTURES

PLATE TECTONICS & IGNEOUS ACTIVITY

DIVERGENT BOUNDARY

INTRAPLATE IGNEOUS ACTIVITY

CONVERGENT BOUNDARY