WELCOME TO PLANET EARTH ~4.6 BILLION YEARS OLD

Inner Core: Solid inner core made up of Iron (Fe) and Nickel (Ni) Solid due to tremendous pressure Outer Core: molten outer core made up of Iron (Fe) and Sulfur (S) Semi-solid due to lower pressures Mantle: mostly solid rock Upper area called Asthenosphere- slowly flowing rock Lithosphere: thin, rigid layer of rock Outermost layer of the earth CONTAINS rigid upper mantle and the crust- our solid surface of the earth.

The Lithosphere floats atop the asthenosphere ---like a cracker on a layer of pudding. Lithosphere moves and breaks into pieces called TECTONIC PLATES ~dozen tectonic plates moving independently from one another Earth sits on 6 giant plates, rest are under the ocean and continents.

Two Types of Plates 1.Oceanic Under oceans Thin Dense and Heavy Always Sinks under 2. Continental Under continents Thick Lighter Never Sinks

Divergent Convergent Transform (sea floor spreading) (with subduction) (San Andreas Fault)

Divergent (normal/constructive) Convergent (reverse/destructive) Transform ( strike- slip/conservative ) plates are moving apart new crust is created Magma is coming to the surface plates are coming together plates are slipping past each other crust is not created or destroyed No volcanism Boundaries Summarized crust is returning to the mantle

Divergent: Sea Floor Spreading Mid Atlantic Ocean Ridge longest topographic feature on Earth (70,000 km!) 2-3 km above ocean basins

Divergent: Sea Floor Spreading

Pillow Lava Rocks under water, marine hotspot volcano chains and the constructive plate boundaries of mid-ocean ridges

Transform Faults Plates move past each other strike slip faults Example: The San Andreas Fault - California

3 Types of plate Collisions OceanicVsContinentalContinentalVsContinentalOceanicVsOceanic Oceanic subducts or SinksNo Subduction (mountain formed) One will subducts or Sinks (heaviest)

Convergent Plate Boundaries Ocean-Continent collision oceanic always subducts or sinks under continental Examples: Nazca plate vs. South American plate (forming the Andes)

Convergent Plate Boundaries Continent-Continent collision No Subduction Example: Indian plate v.s. Eurasian plate (forming the Himalayas, Mt. Everest)

Convergent Plate Boundaries Ocean-Ocean collision One of them always subducts or sinks

Magma molten material beneath the Earth’s crust. collects in a magma chamber beneath a volcano, and can then be injected into cracks in rocks or issue out of volcanoes in eruptions. temperature of magma ranges between 700 C and 1300 C. When it reaches the surface and comes out of a volcano, magma becomes Lava. So the different between magma and lava is location. Magma is deep underground, in chambers beneath volcanoes, and lava is the stuff that comes out of volcanoes.

Post-Pangea movement is supported by evidence, including: 1.Palaeo-magnetism When hot magma rises to the earth's surface and cools, the minerals themselves (especially magnetite) become magnetized in alignment with the Earth's magnetic field. 2.Palaeontology Fossil evidence 3.Geological fit continents seemed to fit together

Evidence that the Ocean Floor is Spreading Magnetic Bands Reversals Lava comes up along ridge lines (mostly underwater) as plates separate. In 76 million years there’ve been 171 reversals of the earth’s magnetic field. Lava contains iron. Cooling lava locks in the prevailing magnetism. The ocean floor near the ridges has the prevailing field and the floor further from the ridges shows field reversals: evidence that the ocean floor is spreading. Rocks and fossils dating Older as one moves away from ridges Youngest rock is next to the ridge Earth's Magnetic Field (General)

Magnetic field reversal Proves the Earth magnetic field reverses itself every years Proves the Earth magnetic field reverses itself every years Another proof that the sea floors are spreading Another proof that the sea floors are spreading

Age of sea floor as measured by fossils - Older as one moves away from ridges - Youngest rock is next to the ridge

Hot Spot Formation of Hawaii

The Pacific Ring Of Fire A collection of earthquakes and volcanoes that make a ring around the Pacific ocean It shows the inter-relation of plate tectonics