Plate Tectonics: Continental Drift

 

Continue our look at the earth's crust

Discussed last time how crust is composed of 2 types of rocks

Basalt and Granite

Understanding the WHY and HOW of this has been a problem since the beginning of geological studies

Introduce concept of plate tectonics

Crust is not rigid, but broken into sections, called "plates"

These are moving around on top of the mantle

Plate boundaries are the site of most global tectonic processes and events (earthquakes, volcanos, etc.)

Development of the theory was hard in coming

 

Continental Drift

Anybody here ever have a good idea?

The idea that the earth's crust is not completely stable is not new

As far back as 1620, Sir Francis Bacon noted the similarity of the coastlines of Africa and South America

1658 - François Placet agreed with Bacon

Proposed that they were "Separated in the Biblical flood"

Mid-1800's: Antonio Snider-Pelligrini

Similar fossil plants in coal beds of Europe and North America

Reconstructed a 'supercontinent'

1908 - Taylor & Baker

Correlation of global mountain chains

All these early ideas were pretty casual

And ran counter to existing dogma: Continents permanent and fixed

Alfred Wegener - 1910

Instructor of Meteorology

Noted trans-Atlantic similarities - seems everyone started here

And took note of the observations of earlier workers

1915 - published his theory of Continental Drift with supporting evidence

Basically said that the continents had been joined into a supercontinent he called "Pangea"

Split apart in the Jurassic along what is now the Atlantic Ocean

Initial response less than overwhelming

Developed into a full fledged battle by 1924

R.T. Chamberlain (American) - "Can we call geology a science when there exists such differences of opinion on fundamental matters as to make it possible for such a theory as this to run wild."

Baily Willis (American, 1944) - Wegener's theory is a fairly tale and should be ignored due to its deleterious effect on students

Wegener was an easy target

Just a weatherman - not an "expert" in any of the fields he was leaning on for support

Easy for opponents to pick holes in specifics

Same old regional vs. local problem

I'm sure Wegener would have loved Strickler's 1st Law of GeoFantasy

In any event, his opponents severely took him to task!

They stirred up a Religious fervor against his work

200 years earlier he would have been toast

They plead for "open-mindedness"

They claimed to be the guardians of the truth against idiotic speculation

Pointed to the lack of a mechanism

Sufficient deficiency to significantly discount Wegener's work

Wegener did have supporters

Carried on his work after he disappeared in 1930