ES-15 Illustrate how the three primary types of plate boundaries (transform, divergent, convergent) cause different landforms (e.g., mountains,
volcanoes and ocean trenches).
Continental crust = less dense
Oceanic crust = more dense
→ ← Convergent Plate Boundaries
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Continental Crust vs. Continental Crust creates Mountains. (Ex. Himalayan Mountains)
1. No subduction occurs when continental crust converges with continental crust.
2. Both edges of the continental plates become crumpled forming mountains.
Continental Crust vs. Oceanic Crust creates a subduction zone (Trench)
1. The Oceanic Crust is subducted under the Continental Crust.
2. As it goes deeper into the asthenosphere it starts to melt.
3. The magma is less dense than the surrounding rock and rises to the top.
4. Volcanoes form from the rising magma.
Oceanic Crust vs. Oceanic Crust creates a subduction zone (Trench)
1. The older oceanic crust is denser therefore it is subducted under the less dense younger oceanic crust.
2. As the subducted plate moves deep into the asthenosphere, it melts causing the less dense magma to rise to the
surface.
3. Remember that this is all occurring in the ocean.
4. The volcanoes created here are called island arcs.
← → Divergent Plate Boundary
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As the plates move apart, new crust is being made from the rising magma.
The areas that new crust is being made are called
1. Rift Valleys
2. Mid Ocean Ridges
3. Spreading Centers
Rocks get older as they move away from Mid Ocean Ridges.
The process of sea floor spreading causes the older crust to move away from the ridge as the new crust is made.
↑↓ Transform Boundary
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Plates that grind past each other but do not move up or down. They move parallel to each other.
San Andrea’s Fault is an example
Know the following facts:
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Convection Currents occur in the asthenosphere.
The asthenosphere if located in the Mantle of the earth and has the ability to flow.
Lithospheric Plates ride on the plastic asthenosphere.
Density is the main factor in determining what type of collision occurs between two plates. (Ex: A pound of Lead is denser
than a pound of Cotton.)
The Mid-Atlantic Ridge is an example of a Mid-Ocean Ridge located in the Atlantic Ocean.
Igneous Rock – formed from cooling magma or lava
Sedimentary Rock- formed from the cementing or compacting of sediments created by weathering and erosion.
Be able to describe the following about Continental Drift.
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Who developed this theory?
What was the evidence he used to support this theory?
What did he name the single land mass and the huge ancient ocean?
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