Physical Geology Overview

Geology Overview

• Definition: Geology is the scientific study of Earth.
• Physical Geology focuses on Earth's materials, surface and internal changes, and the driving forces behind these changes.

Resource Consumption

• Average American consumption of materials:
  • Nonmetals: ~8.666 kg/year
  • Metals: ~147 kg/year
  • Energy: 958 gallons of petroleum, 1908 kg of coal, 2775 m³ of natural gas, 0.06 kg of Uranium.

Earth as a System

• Closed Systems: Permit energy exchange but not matter with surroundings.
• Open Systems: Allow both energy and matter to flow in and out.

Earth Systems Components

Atmosphere

• Composed mainly of nitrogen; supports life.
• Divided into layers:
  • Troposphere: Lowest layer where weather occurs; warms from the base.
  • Stratosphere: Contains ozone layer; temperature remains constant up to 20 km, then gradually increases until 50 km.
  • Mesosphere: Temperature decreases until mesopause, reaching about -90°C above 80 km.
  • Thermosphere: Temperature increases due to solar radiation absorption; location of the International Space Station (330-435 km altitude).

Hydrosphere

• Refers to all water on or near Earth’s surface.
• Oceans cover 71% of Earth's surface; 97.5% is saltwater, 2.5% is freshwater (from glaciers, groundwater, rivers, lakes).

Ocean Geography

• Northern Hemisphere: Known as the land hemisphere (61% land, 39% water).
• Southern Hemisphere: Known as the water hemisphere (81% water, 19% land).
• Pacific Ocean: Largest and deepest ocean; spans from Arctic to Antarctic Oceans.
• Indian Ocean: Third largest, primarily in the Southern Hemisphere, bordered by Asia, Africa, Australia, and Antarctica.
• Atlantic Ocean: Second largest, bordered by Europe, Africa, and the Americas.
• Arctic Ocean: Smallest and shallowest, only 7% the size of the Pacific Ocean.
• Antarctic Ocean: Also known as the Southern Ocean; defined by Antarctic Convergence, located around 50° south latitude.

Biosphere

• Encompasses all living and once-living materials.
• Earth is the only known location to support life; includes ecosystems from soil to rainforests and oceans.

Geosphere

• Solid, rocky component of Earth, differentiated into Crust, Mantle, and Core.
• Planetary Differentiation: Process leading to Earth's layered structure based on material density.
• Lithosphere: Uppermost mantle and crust; rigid, prone to stress leading to earthquakes.
• Asthenosphere: Below lithosphere, where convection occurs, extending to 660 km depth.
• Mesosphere: Lower mantle, from 660 km to 2900 km depth; strengthens with depth.
• Outer Core: Liquid layer from 2900 km to 5150 km; generates Earth's magnetic field via convection.
• Inner Core: Solid core from 5150 km to Earth's center, composed primarily of solid iron due to immense pressure.

Layering of the Earth

• Layering based on Physical Properties: Describes structure based on density.
• Layering by Chemical Properties: Distinguishes layers as solid or liquid, affected by strength and state.
• Crust Thickness: Ranges from 5 km to 80 km, the thinnest layer of the Earth.