TECTONICS - an introduction


General Review

Taking a VERY BROAD regional view...

Earth has 2 levels

Above & below sea level

Earth has 2 types of rock

Granite and basalt

Earth has 2 processes

Construction and Destruction

Over the course of geologic time these 2 are in balance

The destructional processes are covered in The Hydrosphere

The constructional processes are called tectonics

Constructional processes

My favorite part of geology

Tectonics: the study of earth processes which result in the creation and deformation of magma and rock

Show on overhead and define all terms

Some are real flashy: get videodisc frames

Volcanoes (839, 848, 897, 899, 949, 961, 978)

Earthquakes (1912-15, 3332-38, 3354-56)

All involve stress at varying degrees of intensity (1816-17, 1832, 1868)

Obviously, there is nothing on the surface capable of causing these immense tectonic events

Therefore, major earth stress must originate inside the earth

Volcanoes, earthquakes are excellent indicators of immense stress at depth

It's also pretty obvious that these forces must act fairly slow

Remember, entire continents are moving

Try to move them too fast and the results would be amazing!

DIGRESS TO: Strickler's 2nd Law of GeoFantasy

But the effects can be seen at the surface...

Mt. St. Helens - a good (recent) example of how tectonic processes can affect the surface

Before (913)

During (918-22)

After (927)

The earth is a huge ball of magma, and it gets real hot and tight real soon with depth

More on this soon

In any event we will be studying these and other processes

Need to start at the beginning with a brief overview of ideas on creation