The Earth’s Interior Composed of 4 layers Crust Mantle Outer Core Inner Core

Crust Temperature: Over 175 degrees Celsius Topmost layer of the Earth Relatively cool Made of rock 2 types of crust Oceanic (4-7 km thick) Continental (20-40 km thick)

Mantle Temperature: Over 1250 degrees Celsius Makes up about 80% of the Earth’s volume ~ 2900 km thick Outer mantle – rocks Inner mantle – “plastic”

Core Temperature: Over 6000 degrees Celsius Outer core – liquid Pressure from the mantle & crust do not allow the metals in the outer core to become gasses Inner core – solid Pressure from the mantle and crust do not allow the metals to become liquid

Plate Tectonics The Earth’s lithosphere is made up of 7 tectonic plates Plate tectonics – the movement of these lithospheric plates

Why do the plates move? One theory suggests that plates move due to the convection currents in the asthenosphere (“plastic” inner portion of the mantle)

Divergent Plate Boundaries 2 plates move apart Magma fills the gap created from this movement Magma cools as it reaches the Earth’s surface creating rift valleys

Convergent Plate Boundaries Oceanic plates dive beneath continental or oceanic plates (called subduction) Creates deep ocean trenches

Wall diving- coral reefs form over time on the “walls” of deep sea trenches. Many are thousands of feet deep.

Convergent Plate Boundaries Mountains form at the convergent plate boundaries as magma from the mantle rises, pushing continental crust upward

Convergent Plate Boundaries Volcanoes form at the convergent plate boundaries as magma rises to the surface and cools

Transform Fault Boundaries Plates move past each other at cracks in the lithosphere (called faults) Transform fault boundary – horizontal movement between two plates

Earthquakes Occur at plate boundaries Plates slide past each other creating pressure Rocks break along the fault line Energy is released, called seismic waves

San Andreas Fault

Focus = point of earthquake origination Epicenter = point on the Earth’s surface directly above the focus

Energy from an earthquake Energy is released in the forms of waves P wave: Primary or longitudinal waves originate from the focus & move quickly through rock. These are the first waves to be recorded S wave: Secondary or transverse waves originate from the focus & moves more slowly through rock. Surface waves: move across the earth’s surface, causes building to collapse

Earthquake Measurement Seismograph Records data about P, S and surface waves Used to locate the epicenter of an earthquake Richter scale Measures energy released at the epicenter of an earthquake (in magnitude) Each step up in magnitude represents a 30-fold increase in energy released!

Volcanoes Volcanoes result from openings or vents in the Earth’s surface Magma reaches the surface through these vents When magma reaches the surface it changes physically and is called lava

Shield Volcano Formed from fluid lava, rich in iron Shield volcanoes are large Mauna Loa in Hawaii

Composite Volcano Made of alternating layers of lava, ash and cinders. Magma is rich in silica and thick Large with steep slopes

Cinder Cone Large amounts of gas are trapped in the magma causing violent eruptions Active for short periods of time

Minerals & Rocks Minerals: Rocks: naturally occurring, inorganic substances (inorganic = does not contain Carbon) can be expressed by a chemical formula Quartz SiO2 (silicon dioxide) Rocks: Composed of minerals

Types of Rock Igneous Sedimentary Metamorphic Formed when magma or lava cools and hardens Magma forms intrusive igneous rock Lava forms extrusive igneous rock Sedimentary Formed when rock particles, plant and animal debris are carried away by water, redeposited, then fused together Metamorphic Rock particles are fused together by pressure beneath the Earth’s surface

Determining the age of rocks Two ways to “determine” the age of a rock: Superposition – determine the age based on layers, older rocks are on the bottom, newer ones on top Radioactive dating

The Rock Cycle

Weathering and Erosion Two types of weathering Physical Breaks rocks into smaller pieces, chemical composition does not change May be caused by ice or plants Chemical Changes the chemical composition of rocks May be caused by oxidation or acid rain

Erosion Erosion: the process of loosening and removing sediment Caused by water, glaciers, wind

Deposition Occurs when loose sediment is laid down Causes river beds to widen and deltas to form.

Important Elements Oxygen – most abundant element in the Earth’s crust Nitrogen – most abundant element in the atmosphere Iron – most abundant element in the core