GY 111: Physical Geology - PDF Free Download

UNIVERSITY OF SOUTH ALABAMA GY 111: Physical Geology Lecture 3: The Rock Cycle Instructor: Dr. Douglas W. Haywick

Last Time 1. Alfred Wegener and Drifting Continents 2. The Plate Tectonic Revolution 3. Plate Tectonics Mechanisms

Wegener s hypothesis: 300 million years ago, the continents were all grouped together into a supercontinent he called Pangaea

His supporting evidence? Matching rock types and fossils* * types and ages

And although Continental Drift was rejected... Wegener got it right about Pangaea

The Plate Tectonics Revolution Radar, sonar, and depth sounding revealed that the ocean bottoms were not flat planes

The Plate Tectonics Revolution Paleomagnetism shows that the ocean floor youngest near the ridges and oldest near the continents

Paleomagnetism

The Plate Tectonics Revolution The outer part of the Earth is broken up into several large tectonic plates

The Plate Tectonics Revolution And where they rub against one another, you get Earthquakes

The Plate Tectonics Revolution Volcanoes (active, dormant and extinct)

The Plate Tectonics Revolution http://shadow.eas.gatech.edu/~anewman/classes/geodynamics/misc/worldmap.gif and mountain belts

Internal guts of the Earth Four Major Geophysical Layers 1) The Crust (rigid rock) 2) The Mantle (rigid, upper; ductile, lower) 3) The Outer Core (liquid metal; Fe/Ni) 4) The Inner Core (solid metal; Fe/Ni)

The Plate Tectonics Mechanism Heat exchange gives rise to Convection Currents

The Plate Tectonics Mechanism Collectively, the rigid outer most part of the Earth (about 100 km thick) is called the Lithosphere Tectonic layers Lithosphere: Geophysical layers Cooler Athenosphere: Mantle Hotter

The Plate Tectonics Mechanism It is postulated that the convection currents can eventually break up the lithosphere into separate plates Tension Cooler Mantle Hotter

The Plate Tectonics Mechanism Hence the term plate tectonics Tension Asthenosphere New stuff follows from here.

Today s Agenda 1. Plate Tectonic boundaries 2. Introduction to rocks 3. The Rock Cycle Web notes 3:

Plate Tectonic Boundaries Tectonic plates can interact in one of 3 ways

Plate Tectonic Boundaries Tectonic plates can interact in one of 3 ways 1) Move away from one another: Divergent Plate Boundary

Plate Tectonic Boundaries Tectonic plates can interact in one of 3 ways 1) Move away from one another: Divergent Plate Boundary 2) Move towards one another: Convergent Plate Boundary

Plate Tectonic Boundaries Tectonic plates can interact in one of 3 ways 1) Move away from one another: Divergent Plate Boundary 2) Move towards one another: Convergent Plate Boundary 3) Slide past one another: Transform Fault Plate Boundary

Divergent Plate Boundaries

Convergent Plate Boundaries

San Andreas Fault Transform Fault Boundaries

Rocks Rocks are naturally occurring solids containing one or more minerals.

Rocks Rocks are naturally occurring solids containing one or more minerals. They come in many, many, many different flavors

Rocks Rocks are naturally occurring solids containing one or more minerals. e.g., Granite

Rocks Rocks are naturally occurring solids containing one or more minerals. e.g., sandstone

Rocks Rocks are naturally occurring solids containing one or more minerals. e.g., gneiss

Rocks We recognize 3 major rock groups:

Rocks We recognize 3 major rock groups: 1) Igneous ( born of fire ); originally molten

Rocks We recognize 3 major rock groups: 1) Igneous ( born of fire ); originally molten 2) Sedimentary; originally particulate material or produced from precipitation out of water

Rocks We recognize 3 major rock groups: 1) Igneous ( born of fire ); originally molten 2) Sedimentary; originally particulate material or produced from precipitation out of water 3) Metamorphic; pre-existing rocks modified by pressure or temperature

Igneous Rocks Can be either extrusive (volcanic) or intrusive (plutonic):

Igneous Rocks Can be either extrusive (volcanic) or intrusive (plutonic): Extrusive (volcanic) rocks can be erupted as lava

Igneous Rocks Can be either extrusive (volcanic) or intrusive (plutonic): Extrusive (volcanic) rocks can be erupted as lava, or as pyroclastic material (e.g., ash)

Sedimentary Rocks We recognize 4 major classes of sedimentary rocks:

Sedimentary Rocks We recognize 4 major classes of sedimentary rocks: 1) Siliciclastic: composed of broken bits of silicate minerals; Alluvial fan

Sedimentary Rocks We recognize 4 major classes of sedimentary rocks: 1) Siliciclastic: composed of broken bits of silicate minerals 2) Biochemical: mostly composed of the remains of calcium carbonate-secreting beasties 3) Chemical; formed through chemical precipitation alteration Salt flat

Metamorphic Rocks We recognize 3 divisions of metamorphic rocks:

Metamorphic Rocks We recognize 3 divisions of metamorphic rocks: 1) Foliated; display a prominent layering schist

Metamorphic Rocks We recognize 3 divisions of metamorphic rocks: 1) Foliated; display a prominent layering 2) Non-foliated; do not display layering marble

Metamorphic Rocks We recognize 3 divisions of metamorphic rocks: 1) Foliated; display a prominent layering 2) Non-foliated; do not display layering 3) Cataclastic; composed of broken up bits of rock mylonite

The Rock Cycle

The Rock Cycle Metamorphic Loop Igneous Loop Sedimentary Loop

Today s Homework 1. Download and read web notes 3 2. Organize your notes Next Time 1) Quiz 2 (fill in the blank questions) 2) Basic Chemistry

GY 111: Physical Geology Lecture 3: The Rock Cycle Instructor: Dr. Doug Haywick dhaywick@southalabama.edu This is a free open access lecture, but not for commercial purposes. For personal use only.