Jonathan Signater CSS 1302-02
10-18-13 Medhurst

General Purpose: To inform (Theory)

Specific Purpose: My purpose is to inform my audience about the theory of Continental Drift.
Central Idea: My central idea is making sure my audience has a better understanding of the Continental Drift and how the theory was formulated.

The Continental Drift Theory`

I.(Introduction) For years scientists struggled to explain how similar rocks and fossils were found on continents that are far apart from each other. Until the 20th century when scientist Alfred Wegener's theory of Continental Drift was introduced.
A. "Before Wegner introduced his theory it was thought that mountains formed because the Earth was cooling down, and in doing so contracted. This was believed to form wrinkles, or mountains, in the Earth's crust. Wegener suggested that mountains were formed when the edge of a drifting continent collided with another, causing it to crumple and fold". ("The Earth in the Universe,"1999) -BBC reference.

1. Alfred Wegner noticed that the continents seemed to fit together at the edge of their continental shelves .
2. He noticed this because he observed that continents in the Southern Hemisphere have similar rock and fossil patterns.
B. He believed that the continents were all once apart of a large supercontinent called Pangea.
II. Aside from fossils and rock patterns there were other observations that led to his theory.
A. "Glacial till deposits in the Southern Hemisphere aided Wegners hypothesis".("The supporting Evidence of Plate Tectonic Theory",2008)
1. Glaciation till is unsorted glacial sediment left behind by glaciers during the glacial drift.
2. "Glaciation in South America, Africa, India, and Australia is best explained if these continents were