Lets review The earth lithosphere is broken into

Let’s review…. The earth lithosphere is broken into sections called tectonic plates. These plates float around on the asthenosphere. The magma in the asthenosphere is rising and sinking due to differences in density and temperature. This movement is called a convection current. Because the magma is moving in the asthenosphere, the tectonic plate is also moving!!

The edge of each plate is called a Plate boundary • When plates move, they interact with each other at the boundaries. Sometimes, they crash into each other, other times they pull away from each other, and at other times they slide past each other. Depending on how they move, a different geological event will happen (such as earthquakes, volcanoes, mountains. )

There are 3 types of plate boundaries: • Convergent • Divergent • Transform

1. Convergent Boundaries: When two plates collide or move together.

a. Convergent Oceanic-Continental Plate Boundaries • The Oceanic crust moves toward the continental crust. The Oceanic crust subducts (slides) under the continental crust because the oceanic crust is more dense.

Results • Produces a subduction zone • Trenches are formed in the ocean 3. Volcanoes form on land. Labeling: A. Oceanic Crust B. Continental Crust C. Volcanoes D. Trench

b. Convergent Oceanic-Oceanic Plate Boundaries: Two Oceanic plates are coming together. The older Oceanic crust will sink below the newer Oceanic crust because the older crust is colder and more dense.

Results: 1. Produces a subduction zone 2. Trenches form in the ocean 3. Volcanic Islands form in the ocean Labeling: A. Oceanic Crust B. Oceanic Crust C. Subduction Zone D. Volcano

C. Convergent Continental Plate Boundaries • Two continental crust coming together. They will rise because they are both less dense than the material in the asthenosphere.

Results: 1. When they collide mountains (non volcanic) are formed. Labeling: A. Continental Crust B. Continental Crust C. Mountains

2. Divergent Boundaries: Two plates move apart

a. Diverging Oceanic and Oceanic plate boundary– two ocean plates are moving apart. Results in seafloor spreading, and mid-ocean ridges being formed.

Labeling: A/B Oceanic Crust C. Rift D. Mid-Ocean Ridge E. Trench F. Subduction Zone G. Volcanoes

b. Diverging continental boundaries. • 2 continental plates moving apart. • Results in rift valleys.

Transform Boundaries: Two plates slide past one another. They move in opposite directions at different rates (speeds).

Results: 1. Earthquakes occur here. 2. Tsunami: which are underwater earthquakes **Can occur with any plates sliding past each other.

Tsunamis

Results all over the world due to where boundaries meet.