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