Planet Earth:
Spheres of the Earth Atmosphere Biosphere Hydrosphere Lithosphere Magnetosphere Anthroposphere
Six Spheres 1. LITHOSPHERE: The Solid Earth Tectonic processes. Volcanic processes. Gradational processes. Impact cratering. 2. HYDROSPHERE: The Water State of water - gas, liquid, or solid. Ocean distribution and currents. Drainage patterns. Glaciers. Tidal forces.
Six Spheres 3. ATMOSPHERE: The Air Convection. Zonal flow. Storms. General circulation patterns. 4. MAGNETOSPHERE: Magnetic field and Charged Particles Interaction with the solar wind. Bow shock front. Interaction with atmosphere.
Six Spheres 5. BIOSPHERE: All Living Matter Origin of life. Effect of life on atmospheric evolution. 6. ANTHROPOSPHERE: Homo Sapiens Impact Interactions of Homo Sapiens with all aspects of the environment.
Why Study the Earth? Easiest to study and best understood Serves as model for other planets processes within, on, and around planet properties of planets Atmosphere: formation, composition, and evolution Hydrosphere Solid body interior structure surface features: formation and modification Magnetic field Life and its affect
The Earth s Shape and Size Round/spherical ancient Greeks and Romans Aristotle: lunar eclipse, stars at horizon Magellan: 1 st to circumnavigate the globe, and proved that the earth is round. Modern measurements show Earth to be pear-shaped.
Earth in Cross-Section Solid Earth - Lithosphere Inner core: 1300 km radius Outer core: 1300-3500 km Mantle: 3500-6400 km Crust: tops mantle, 5-50 km Hydrosphere: water phases at surface Atmosphere: tops hydrosphere; majority within 50 km of surface Magnetosphere: outermost region, extends 1000 s of km out into space
Solid Earth Solid Earth Inner core 1300 km radius Outer core Mantle Crust: 1300-3500 km 3500-6400 km tops mantle 5-50 km
Dense, metallic The Earth s Core Primarily iron, some nickel and sulfur 16% of Earth s volume Two sections outer core depth of 2900 km to 4400 km liquid inner core total diameter ~2600 km (larger than Mercury) solid, very dense
The Earth s Mantle Mantle stretches from outer core boundary, upwards 2900 km. It is ~84% of Earth s volume lower region - dense, strong, high pressure upper region, called the asthenosphere. has reduced pressures and rock strength Plastic rock (at pressures and temperatures found in this region, mantle rock can deform and flow slowly).
Earth s Crust Crust: makes up 0.3% Earth s mass Two types Oceanic crust covers 55% of the surface ~ 6 km thick composed of basalts - iron-magnesium-silicate Continental crust covers 45% of the surface 20 to 70 km thick predominately granites: more silicon and aluminum than basalts
Crust is broken into pieces called tectonic plates Plates are made of rigid lithosphere (crust and the upper part of the mantle All tectonic plates move in different directions (1-2 inches per year)
Continental Drift In 1915, Alfred Wegener proposed that up until about 200M years ago, all of the present continents were joined together into a super-continent he called Pangea.
Plate Movement Plates of lithosphere are moved around by the underlying hot mantle convection cells
Three types of plate boundary Divergent Convergent Transform
Divergent Boundaries Spreading ridges As plates move apart new material is erupted to fill the gap
Iceland: An example of continental rifting Iceland has a divergent plate boundary running through its middle
Convergent Boundaries There are three types of convergent plate boundaries: Continent-continent collision Continent-oceanic crust collision Ocean-ocean collision
Continent-Continent Collision Forms mountains, e.g. European Alps, Himalayas
Himalayas
Continent-Oceanic Crust Collision Subduction Oceanic lithosphere subducts underneath the continental lithosphere Oceanic lithosphere heats and dehydrates as it subsides The melt rises forming volcanism E.g. The Andes
Ocean-Ocean Plate Collision When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench. The worlds deepest parts of the ocean are found along trenches. E.g. The Mariana Trench is 11 km deep!
Transform Boundaries Where plates slide past each other Fence offset produced by tectonic plates movement San Andreas transform fault
What are the consequences of the tectonic plates movement? Landscape formation Volcano formation Earthquakes Tsunami formation