CSULA - Introduction to Geology

What is Geology?

geo = Earth
ology = the study of
OR, a science that deals with the history of the Earth and its life, especially as recorded in rock (Merriam-Webster Online Dictionary)
Physical geology - examines the materials composing Earth and seeks to understand the many processes that operate beneath and upon its surface
Historical geology - seeks an understanding of the origin of Earth and its development through time

Scientists assume the natural world is
- Consistent
- Predictable
Our goal:
- Discover patterns in nature
- Use these patterns to make predictions
The Scientific Method

Earth is a small, self-contained planet
All parts of the Earth interact with one another
The Four “Spheres” of the Earth
- Atmosphere
- Biosphere
- Hydrosphere
  - Includes the hydrologic cycle.
- Lithosphere
Processes powered by:
- The Sun
- Heat from the Earth’s interior
Early evolution of Earth
- Formation of the Earth
  - The Earth formed by the accretion of cold particles.
    - The surface was then heated due to meteor impacts
    - This caused the Earth to partially melt & density stratification.
  - First surface on the Earth formed ~4.6 billion years ago.
  - A collision with a rocky body about the size of Mars smashed into the Earth
    - Rocky mantle of the object formed a debris ring around the Earth
    - The metallic core merged with the Earth’s
  - Radiation from the Sun stripped the outermost layer of gasses (1st atmosphere) from the Earth
    - Gasses trapped within the Earth were released and formed a 2nd atmosphere.
  - Outgassing formed first clouds
  - After millions of years, the clouds cooled enough to create rain
    - Cooled the surface and eroded the first rocks
    - Rains may have lasted as long as 25 million years.
    - Water may have covered the Earth’s surface for 200 m.y.!
Earth’s internal structure
- Earth’s internal layers can be defined by
  - Chemical composition
  - Physical properties
The Earth Today
- Our planet is a dynamic place
- Plate tectonics
- Erosion
- Interaction between the Atmosphere and Oceans = weather