Apologia Physical science module 6 continued. Plate tectonics.

Plate tectonics, what are they?

from Enchanted Learning

If you have studied earth or physical science before, you will most likely have heard of plate tectonics, if not, here is what we learned about plate tectonics.

Plate tectonics is also related to the last lesson about the asthenosphere which you can read here on my blog, Horsing Around At Home.

A little background first.  The common theory is that all continents used to be one super landmass called a Pangaea (Greek for all land) and that over time, they have drifted apart.  This is known as the continental drift and was suggested by a German climatologist, Alfred Wegener, in the early 1990s.

~Earth is in constant motion.  You may not realize it because the movements are so slow.

~Earth moves between one to six inches every year but it takes millions of years to move a significant amount.

~The lithosphere is the part of land that is moving Earth (the crust and upper mantle).

~Plate tectonics are moved by the lithosphere.

PNSN

~There are seven major plates on Earth which include Africa, Antarctic, Eurasia, North America, South America, India-Australian, and the Pacific plates.

~There are around eight smaller plates which include Arabian, Caribbean, Nazca, and Scotia.

~There are two main types of lithospheric plates which are oceanic and continental.

~Oceanic plates form on the ocean floor and are thin and made from basalt.

~Continental plates are thick and made of semi-dense granite.

From Enchanted Learning

~The tectonic plates have three main boundaries:

 *convergent-is where two plates push together.  Occasionally one plate will move under the other which is known as subduction.  The Mariana Trench is the deepest part of the ocean and was formed between the Pacific Plate and the Mariana Plate.  The Pacific Plate is subducted under the Mariana Plate.  Another example of a convergent boundary is the Himalayan Mountains, boundaries of the Indian Plate and the Eurasian Plate.

 *divergent-are found in the ocean as mid-ocean ridges and in rift valleys when a rift valley forms on land.

 *transform-a boundary where two plates slide past each other.  This forms a fault, earthquakes occur frequently at this type of boundary.  San Andreas Fault is a good example of this boundary.  The transform boundary here is located between the North American Plate and the Pacific Plate.

This is the point I am breaking this topic into another blog post about earthquakes, volcanoes, and mountain formation.

Geography 4 Kids

Plate tectonics on Pinterest

A great printable can be found here.
Science Clarified