Earth’s system spheres

• Interacting series of spheres or layers– Atmosphere– Hydrosphere– Geosphere– Biosphere

Atmosphere

• Relatively thin gas layer

• Nitrogen (78%); oxygen (21%); minor gases incl. Ar, CO2, water vapor

• Gravity holds it in place

• 99% below 30 km altitude

Hydrosphere

Biosphere•Contains all life forms on Earth•Overlaps with upper-most geosphere •Contains all of the hydrosphere and smallamount of lowerasthenosphere

Geosphere

• Extends from Earth’s surface to center of the Earth

• Layered feature• Lithosphere – solid rock• Asthenosphere – weak

material• Crust is very thin• Denser toward center of

Earth

• Note the various layers (spheres) present in the diagram

• Note how the continental material depresses the weaker underlying layers

• Note relative thickness of oceanic vs continental crust

Earth’s outer layers

Key elements in Earth’s crust

Layers of the geosphere

• Crust– Continental– Oceanic

• Mantle (gradational)• Outer core (liquid)• Inner core (solid)

Processes forming Earth

• Major role players in generating natural hazards; all are interrelated– Tectonic cycle– Rock cycle– Hydrologic cycle– Biochemical cycle

Tectonic cycle

• Cratonic material (solid center of continents); passive area; away from edges

• Active and passive plate margins• Large-scale processes deform Earth’s crust;

earthquakes and volcanoes are generated

Heat transfer methods

Lithospheric plates• Note continental vs. oceanic plates

Types of plate boundaries

• Divergent• Convergent– Oceanic – oceanic – Oceanic – continental

• Transform

Relationship of plate boundaries

Example of divergent boundary

• Note direction of movement

Types of plate convergenceOceanic - continental

• What features are formed?

Continental – continental

• How does this differ from the figure to the left?

Oceanic-oceanic convergence forms island arcs

Continent – continent convergence

• How does this differ from previous collisions?

Example of continent-continent collision

Transform faults

• What is different here?

Example of transform faulting

• What is missing fromother faulting situations we have seen?

Rock cycle

Hydrologic cycle

• The water balance on Earth

Biogeochemical cycle

• Carbon and nitrogen are cycled through the hydrosphere, atmosphere, and lithosphere– Respiration– Photosynthesis– Decomposition

Carbon cycle• C is in all organic substances; also in all

spheres