PLATE TECTONICS

TEKS 8.9B relate plate tectonics to the formation of crustal features; TEKS 6.10C identify the major tectonic plates TEKS 6.10D describe how plate tectonics causes major geological events such as ocean basins, earthquakes, volcanic eruptions, and mountain building

What is Plate Tectonics? Plate tectonics describes the means by which the oceanic and continental crust are able to move and the results of that motion.

The crust of Earth is divided into plates. Key plates: Eurasian African Indo-Australian Pacific Nazca North American South American

The plates are rigid and in constant motion relative to one another.

What Causes the Tectonic Plates to Move?

Intense heat from the core of the Earth causes convection cells to form in the asthenosphere.

The Earth’s continental and oceanic plates sit on the hot asthenosphere. While the rock in the asthenosphere is solid, it is less rigid than the plates, and therefore moves.

While scientists do not fully understand the forces that move the plates, it is believed that the moving material in the asthenosphere drags the plates along.

What Are the Results of Tectonic Plate Motion?

Each plate moves as a distinct unit Each plate moves as a distinct unit. The borders between plates are called plate boundaries.

There are three different kinds of motion that occurs between the tectonic plates. Divergent Plate Boundary Transform Plate Boundary

I can out run the tectonic plates! Even though the motion of the plates is very slow; about 10-40 mm/year (this is about how fast your fingernails grow), the motion causes major geologic events and surface features. I can out run the tectonic plates!

TRANSFORM Surface Feature: faults Motion: plates grind past one another Geologic Event: earthquakes

San Andreas Fault Click here!

DIVERGENT Surface Feature: Rifts Rift valleys Volcanic islands mid-ocean ridge Motion: plates move away from one another Geologic Event: new crust is formed shallow earthquakes

rift valley Click here! Mid-Atlantic Ridge

CONVERGENT Geologic Event: Motion: plates move toward from one another crust material is destroyed earthquakes volcanic eruptions mountain building Motion: plates move toward from one another

CONVERGENT Surface Features: volcanoes Island arcs Volcanic arcs Trenches Mountain ranges

Mount Saint Helens Click here!

The Himalayan Mountains Click here!