Plate Tectonics

Tectonic Plates

Continental Drift http://youtu.be/_5q8hzF9VVE

Continental Drift Geologist Alfred Wegener-first to propose evidence that continents were once connected. He called this “super” continent Pangaea, meaning “All Earth”

Pangaea

Political Pangaea

Support for Continental Drift Shape of the continents They fit together like jigsaw puzzle pieces.

Support for Continental Drift 2. Fossil Correlation SAME FOSSILS : DIFFERENT CONTINENTS

Support for Continental Drift 3. Rock and Mountain Correlation SAME ROCK : DIFFERENT RANGE Existing mountain ranges separated by vast oceans contain rocks of identical mineral content. Ex: Appalachian Mtns in the eastern US and Caledonian Mtns in the British Isles

Support for Continental Drift 4. Past Climate Data (Paleoclimates) Glacial Scars show past cold climate SAME SCARS : DIFFERENT CONTINENTS Coal Deposits show past warm climate

Glacial Scars

Coal Deposits

Continental Drift in Doubt Why didn’t people believe in continental drift? People couldn’t imagine how the Earth could be millions of years ago. People couldn’t imagine a force great enough to move the continents. BUT…by the 1960s, evidence would prove continental drift is TRUE!

How Plates Move http://pubs.usgs.gov/gip/dynamic/unanswered.html

The Lithosphere & The Asthenosphere The lithosphere floats on top of the asthenosphere. Convection currents that occur in the asthenosphere, cause the lithosphere to move. This creates/destroys landforms on Earth’s crust.

Sea Floor Spreading http://youtu.be/6CsTTmvX6mc

Sea Floor Spreading Harry Hess-1960s Discovered the Mid-Atlantic Ridge while mapping the ocean floor. Mid-Ocean Ridges-underwater mountain chains Magma rises to the surface and solidifies to form new oceanic crust. Older crust is pushed farther away from the ridge

Sea Floor Spreading

Plate Tectonics The theory that Earth’s crust and upper mantle (lithosphere) are broken into sections, called plates, that slowly move around on the rest of the mantle (asthenosphere) due to convection currents.

Types of Crust The type of crust present and the direction of the convection current determines how Earth’s surface will be effected. Oceanic: made primarily of basalt; more dense Continental: made primarily of granite; less dense

Different Types of Boundaries http://pubs.usgs.gov/gip/dynamic/understanding.html

Divergent Boundary – Arabian and African Plates Arabian Plate Red Sea African Plate

Divergent Boundary – Iceland http://pubs.usgs.gov/gip/dynamic/understanding.html

Divergent Boundary - Oceanic http://www.geology.com

Divergent Boundary - Continental http://www.geology.com

Convergent Boundary – Indian and Eurasian Plates Indian Plate

Convergent Boundary – Oceanic & Continental http://pubs.usgs.gov/gip/dynamic/understanding.htmlhttp://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Convergent Boundary – Oceanic & Oceanic NOTE – PLATES ARE REVERSED http://pubs.usgs.gov/gip/dynamic/understanding.htmlhttp://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Convergent Boundaries - Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Transform Boundary – San Andreas Fault www.geology.com

Review Name the 3 main layers of the Earth What is a tectonic plate? What was Pangea? What is Sea-Floor spreading? Name the three different types of plate boundaries and one location on Earth for each one