Lecture 1
I. Geology
A. Physical vs Historical Geology

Physical Geology- Origin, classification, and composition of Earth materials
and internal and surficial processes

Historical Geology- Earth evolution, changes in lands and seas, mountain
building and destruction, fossil succession through time, and history of the
solar system
B. Scientific Method
a. Questions
b. Collection of Data
c. Development of Hypothesis
d. Testing of Hypothesis
II. Formation of the Solar System
A. Solar Nebula Hypothesis
a. Cold, Rarified cloud of gas and dust particles
b. Dust cloud starts counterclockwise rotation
around proto-sun
c. Eddies in dust cloud begin planetary
development: cold homogeneous accretion
d. Protoplanetary formation and gravitational
collapse form Sun
e. Solar wind drives out lighter elements
B. Dynamic Constraints
a. All planet revolve in same direction
b. All planets lie in roughly same plane
c. Nearly all planets and moon rotate counterclockwise
d. Density of planets generally decrease away from sun
e. Planets in two groups:
i. Terrestrial
ii. Jovial
f. All objects roughly the same age
Neighbors in Space
A. Meteorites
a. Chondrites
b. Carbonaceous Chondrites
c. Achondrites
d. Iron and Stony Iron
B. Planets
a. Mercury
i. Moon-like cratered surface
b. Venus
i.Earth’s twin (size)
ii.Volcano dominated landscapes
c. Mars
d. Jupiter
i.Giant Gaseous Planet (The word Jovian
means Jupiter like)
ii.Four inner terrestrial satellites
1. Europa
2. Callisto
3. Ganymede
4. Io
e. Saturn
i. Gas Giant
ii. Ring system and many satellites
f. Uranus and Neptune
i. Also gaseous with many satellites
g. Pluto
i. Ice world
ii. Possible “captured”
III. Earth
1. Formative Eons
A. Hadean: 4.6-3.9 bya
B. .Archean: 3.9-2.5bya
2. Introduction to the Hadean Earth
A. Accretion and Differentiation
i. Heating, partial melting and solid diffusion
ii. Ni and Fe migration to core
iii. Mantle separation forming lighter crust
B. Layers of the Earth
i. Core
(1) Solid metal inner core
(2) Liquid metal outer core
ii. Mantle
(1) Lower Mantle
(2) Upper Mantle
(a) Astenosphere
(b) Lithosphere
(i) Broken into Plates
1. Composed of solid upper mantle and overlying crust
a. Crust- 20-90km thick
i. Continental crust mostly silicon and aluminum with
average density of 2.7 g/cm3
ii. Oceanic Crust considerably thinner (5-10km) composed of
dark basalt with average density of 3 g/cm3
3. Plate tectonics
A. Earth is divided into rigid tectonics plates that move about the astenosphere
B. Probably the most important concept of modern geology
C. Unifying theory that relates many seemingly unrelated phenomena
4. Geologic Time
A. Catastrophism
B. Uniformitarianism