Chapter 1: The Nature of Geology
1.1 Geology - The Study of the Earth
Physical Geology - Materials that make up the earth, and the internal and external and internal processes that shape the earth.
Historical Geology - Origin of the earth and its development through time.
1.2 The Scientific Method
Science is based on the assumption that nature behaves in a consistent and predictable manner; the same physical laws operate everywhere.
The development of scientific knowledge (scientific method) involves:
The collection of scientific facts through observation and measurement (experimentation).
"Everyone saw a falling apple. Isaac Newton wondered why?"
The development of hypotheses which are ideas that can be tested by observation and measurement.
"Falling is caused by gravity"
The formulation of theories which are mature hypotheses having stood the test of time, and which unify a variety of observations.
"Theory of Gravity" All matter is attracted to other matter. Test the theory.
The establishment of scientific laws and principles which are generalizations that explain some phenomenon for which there is no known deviation.
Hasn't ever been disproved. Has been modified.
See handout: "An Invisible hand?" from the Economist, 19 August 2004.
1.3 Early Earth: Formation of a Layered Planet
Thermal evolution
Heat of accretion plus radioactive heating led to partial melting of the result was differentiation — iron and nickel sank to form the inner and outer core while the rocky material rose to form the mantle and the crust.
Earth's interior is characterized by gradual increases in temperature, pressure and density. Heat continually flows outward into space.
Temperature at 100 km. is between 1200°C and 1400°C, while the temperature at the earth's center is about 6700°C.
The temperature and pressure greatly affect the mechanical behavior or strength of earth materials.