Earth's Subsystems Overview

Earth's Subsystems

• Earth is a system composed of four interrelated subsystems: biosphere, atmosphere, hydrosphere, and geosphere.
• Energy and matter are constantly flowing between these subsystems.

Biosphere

• All living organisms and their abiotic environment that provides energy and nutrients.
• Extends from the atmosphere to the deep sea vents of the ocean.

Atmosphere

• Thin, gaseous layer surrounding Earth.
• Composed primarily of nitrogen (78%), oxygen (21%), argon (0.9%), and trace gases.
• Atmospheric circulation redistributes heat from the sun.

Hydrosphere

• 70% of Earth's surface is covered by water.
• 3% is freshwater, two-thirds of which is ice.
• Regulates heat on the Earth's surface.
• Ocean circulation moves heat around the globe.

Geosphere

• Earth's solid surface, interior, rocks, minerals, and landforms.
• Includes processes that shape Earth's surface.

Geosphere: Internal Structure

• Mantle:
  • Upper mantle: less dense, brittle
  • Lower mantle: thicker, denser, and partly molten (plastic-like)
• Lithosphere: rigid outer layer comprising the crust and upper mantle.
• Asthenosphere: partly molten layer within the upper mantle, allowing for plate tectonic movement.
• Core:
  • Inner core: solid, iron-rich
  • Outer core: liquid, iron-rich, generating Earth's magnetic field.

Minerals

• Naturally occurring, inorganic, solid substances.
• Possess a fixed chemical formula and a specific atomic arrangement (crystal structure).
• 5 defining characteristics:
  • Must be solid under normal Earth conditions.
  • Naturally occurring.
  • Inorganic.
  • Specific chemical composition.
  • Ordered atomic arrangement.

Mineral Properties

• Luster: how light reflects off a mineral's surface.
  • Metallic: shiny, opaque, like polished metal.
  • Non-metallic: glassy, brilliant, resinous, silky, pearly, dull, earthy, greasy, etc.
• Hardness: resistance to scratching.
  • Mohs Hardness Scale: measures relative hardness by comparing ability to scratch other minerals.
• Color: generally unreliable for identification due to impurities, but can be useful when consistently present.
• Streak: color of a mineral's powder, more reliable than color and a unique property for most minerals.
• Crystal form/habit: shape of a crystal, reflecting its growth pattern.
  • Amorphous: mineral with no defined crystal structure.
• Breakage, Cleavage, Fracture: how a mineral breaks.
  • Cleavage: smooth, flat planes of weakness that result from breakage.
  • Fracture: irregular, non-planar breakage.