Physical Geology

• Physical
 

 - not historical (geologic time)
 - study of Earth materials and processes

• Processes and materials are linked
 
• Earth systems:
 

 - Solid earth (rocks and minerals)
 - hydrosphere (all water)
 - atmosphere
 - biosphere (all organisms)

• Two sources of energy to drive system:
 

 - internal: earth’s internal heat (tectonics)
 - external: solar radiation (erosion)

The scientific method

• Hypothesis development:

- from data gathered by observation and experimentation
- hypothesis tested (questioned) by more observations and experimentation
- do experiments disprove hypothesis?

• If sufficient observations support hypothesis, elevated to theory, e.g.

 - evolution
 - relativity
 - plate tectonics

 
• Practice of geology as a science:
 

 - outdoor
- laboratory experiments
 

• Modern geology:
 

- borrows heavily from chemistry, physics and biology

 
• Understand how Earth evolved by studying modern processes and materials

• Examples:
 

 - eruption of volcanoes
 - wave and stream erosion
 - drifting of continents
- distribution of minerals and rocks on surface

 
• Principle of uniformitarianism:
 

 - “the present is the key to the past”
 - developed by James Hutton (18th century)

• Not always true:
 

 - asteroid impacts
 - huge volcanoes – Columbia river basalts.