Plate Tectonics

Earth’s Layers The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

Here’s the HS EES version…

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 then creates/destroys landforms on Earth’s crust.

Tectonic Plates

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 SAME SCARS : DIFFERENT CONTINENTS Coal Deposits Have been found in temperate and polar regions, however coal is formed in tropical regions.

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!

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 What are the three?

Divergent Boundary - Oceanic

Divergent Boundary - Continental

Convergent Boundary – Oceanic & Continental

Real World Effect: Nazca Plate, South American Plate Peru-Chile Trench

Convergent Boundary – Oceanic & Oceanic

Real World Effect: Japanese Islands

Convergent Boundaries - Continental

Eurasian Plate Indian Plate What mountain range is this? Indian Plate

Transform Boundary – San Andreas Fault

Warm-Up COPY & ANSWER each question, please! Name the 3 main layers of the Earth What is a tectonic plate? What was Pangaea? What is Sea-Floor spreading? Name the three different types of plate boundaries and what type of landform occurs at each.