Continental Drift

Earthquakes and volcanoes are a blast to talk about, but what we haven't really discussed is what the driving forces behind such awesome power.  In this section we will discuss the science that led us to an understanding of the driving mechanism behind our mountains, volcanoes, valleys, oceans, and earthquakes.

First lets gain an understanding of Alfred Wegener and his hypothesis of something he called, Continental Drift.

SUSD5 Student Version of The Continental Drift Activity

Purchase the Continental Drift Activity at Teachers Pay Teachers for 0.50 cents.

Before the 1800's there once was a theory of how all of our landmasses ended up in their current locations.  Below is a video that might help you understand how that happened.

Scatt and Pangaea Video.jpg

Scratt was to blame... LOL

In the early 1800's Alfred Wegener, a German scientist noticed that when looking at the continents on a map, they looked like they might have once fit together, like a puzzle.  He hypothesized that maybe at one time all of the continents were joined together in one landmass that Wegener called Pangaea and that the continents have been slowly drifting apart in a process called Continental Drift.  Below is a better video that will explain Pangaea.

Pangaea Explanation Video.jpg

Not only did the continents look like they fit, but he discovered that similar plant and animal fossils were found on different continents.  Some of these fossils were plant that would have a really difficult time getting to the shores of another continent.  Some were mammals that were not swimmers, so how did they get on multiple continents when there are huge oceans in the way.  Some fossils were from organisms that lived in hot tropical climates, but were found where it is very cold.  These were hints that once upon a time continents were joined together.

Mesosaurus fossil

Mesosaurus

 

glossopteris
Glossopteris

 

Cynognathus
Cynognathus

Lystrosaurus
Lystrosaurus

 

Below is an image showing the location of where these fossils have been discovered.

continental drift fossils

Other evidence of continental drift is that glacial deposits, glacial grooves, and other glacier evidence has been found in parts of South America, Africa, India, and Australia.  Glacial evidence has been found in these areas that are much too warm to sustain glacier growth.

yosemite batholith.jpg

Yosemite carved by glaciers in California

 

Glacial Till
Glacial Till Found in California.

 

The last piece of Wegener's hypothesis is that at edges of continents there are similar rock types as well.  An examples would be that many rock types found in the Appalachian Mountains are also found in England.  Wegener hypothesized that maybe England and North America were once joined together.

Similar rock types