Geology Concepts Mr. Clark BHS

Key Concepts  Major geologic processes  Minerals, rocks, and the rock cycle  Earthquakes and volcanoes  Plate Tectonics

Structure of the Earth

Features of the Crust and Upper Mantle

External Earth Processes  Erosion  Mechanical weathering  Frost wedging  Chemical weathering  Biological weathering

Natural Hazards: Earthquakes  Features  Magnitude  Aftershocks  Primary effects  Secondary effects

Expected Earthquake Damage Canada United States No damage expected Minimal damage Moderate damage Severe damage

Natural Hazards: Volcanic Eruptions extinct volcanoes extinct volcanoes magma reservoir central vent magma conduit Solid lithosphere Solid lithosphere Upwelling magma Partially molten asthenosphere

Minerals and Rocks  Mineral (diamond, quartz) Rock Types  Igneous (granite, basalt)  Sedimentary (limestone, sandstone)  Metamorphic (marble, slate)

Igneous Rock Granite, Pumice, Basalt Sedimentary Rock Shale, Sandstone, Limestone Metamorphic Rock Slate, Quartzite, Marble Magma (Molten Rock) Weathering Erosion Transport Deposition Heat, Pressure Heat, Pressure Heat, Pressure Heat, Pressure Rock Cycle

Oceanic crust (lithosphere) Abyssal hills Abyssal floor Oceanic ridge Trench Volcanoes Folded mountain belt Craton Mantle (lithosphere) Mantle (asthenosphere) Abyssal plain Continental crust (lithosphere) Mantle (lithosphere) Continental rise Continental slope Continental shelf Abyssal plain Abyssal floor

Tectonic plate Collision between two continents Oceanic tectonic plate Spreading center Oceanic tectonic plate Ocean trench Plate movement Continental crust Subduction zone Oceanic crust Oceanic crust Continental crust Mantle Inner core Hot outer core Two plates move towards each other. One is subducted back into the mantle on falling convection current. Mantle convection cell Hot material rising through the mantle Material cools as it reaches the outer mantle Cold dense material falls back through mantle

EURASIAN PLATE CHINA SUBPLATE PHILIPPINE PLATE INDIAN-AUSTRLIAN PLATE PACIFIC PLATE JUAN DE FUCA PLATE COCOS PLATE CARIBBEAN PLATE NORTH AMERICAN PLATE SOUTH AMERICAN PLATE EURASIAN PLATE ANATOLIAN PLATE ARABIAN PLATE AFRICAN PLATE SOMALIAN SUBPLATE Carlsberg Ridge Southwest Indian Ocean Ridge ANTARCTIC PLATE Transform fault East Pacific Rise Transform fault Mid- Indian Ocean Ridge Southeast Indian Ocean Ridge Mid- Atlantic Ocean Ridge Reykjanes Ridge Transform fault Divergent ( ) and transform fault ( ) boundaries Convergent plate boundaries Plate motion at convergent plate boundaries Plate motion at divergent plate boundaries

Click to view animation. Animation Plate margins interaction.

Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary Divergent Boundary

Lithosphere TrenchVolcanic island arc Asthenosphere Rising magma Subduction zone Trench and volcanic island arc at a convergent plate boundary Convergent Boundary

Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries

Liquefaction of recent sediments causes buildings to sink Landslides may occur on hilly ground Shock waves Epicenter Focus Two adjoining plates move laterally along the fault line Earth movements cause flooding in low-lying areas

Canada United States No damage expected Minimal damage Moderate damage Severe damage

extinct volcanoes magma reservoir central vent magma conduit Solid lithosphere Upwelling magma Partially molten asthenosphere

Igneous Rock Granite, pumice, basalt Metamorphic Rock Slate, marble, quartzite Magma (molten rock) Heat, pressure, stress Heat, pressure Melting Sedimentary Rock Shale, sandstone, limestone Deposition Transportation Erosion Weathering

White clam Magma Black smoker Sulfide deposit White crab Tube worms White smoker

Geologic Time Scale  Because fossils appeared in a predictable order, one can use them as relative time markers.  What’s more you can define time periods based on certain fossils that were living at that time.  This enabled geologists to construct the Geologic Time Scale and name its periods based on the fossil record.

Plate Tectonics  Divergent boundary  Convergent boundary  Subduction zone  Transform fault

Earth’s Major Tectonic Plates

Plate Tectonics

Plate Tectonics: Fundamentals Evidence - plate tectonics unites many disparate observations Sea-floor spreading - the oceans widening is the mechanism that moves the continents

Plate Tectonics: Fundamentals Plate margins - convergent, divergent, transform Continental crust vs. oceanic crust The Earth’s interior: lithosphere, mantle, core

Continental Drift Alfred Wegener ( )

Wegener’s version of continental drift (1912) Wegener was correct… but he had no mechanism.

Plate Tectonics s New data: –the age of the ocean floor –magnetic stripes

Magnetic Stripes and Seafloor Spreading

Seafloor Spreading

How does seafloor spreading lead to continental breakup?

Plate Margins

Transform fault plate boundaries

Continental vs. Oceanic Crust

Oceanic vs. Continental Crust  Age:  OC = <180 m.y.a.  CC = 2-3 b.y.a.  Thickness:  OC = 5-7 kilometers thick  CC = km

Oceanic vs. Continental Crust  Composition:  OC = basaltic  CC = granitic  Density:  OC = 3.0 grams per cubic centimeter  CC = 2.7 gm/cc

The Earth’s Interior

We know the Earth is layered because of seismic wave data!

The Earth’s interior Composition: –Crust – mafic / felsic –Mantle - ultramafic

The Earth’s interior: 2 bases for layering Viscosity/Velocity: –Lithosphere - rigid & non- flowable, 0-150km –Asthenosphere - soft & flowable, km (  “upper mantle”) –Mantle - transition zone ( km) - lower mantle ( km) –Core

Mantle Convection: the mechanism for plate tectonics?

Plate tectonics explains things, for example... Mountain belts The Hawaiian islands