Theory of Continental Drift

James Hutton 1785 Uniformitarianism He is known as the father of geology

Uniformitarianism The present is the key to the past The geological forces and processes of today are the same as those from the past. These forces are very slow and methodical.

Alfred Wegener 1915 Continental Drift

Evidence for continental drift Matching Coastlines (jigsaw puzzle) Becomes more of a match when you use the continental shelves.

Matching folded mountain Ranges (Atlas, Appalachians, and Scandinavian Highlands)

Matching glacial deposits and erosional features

Salt beds found in Texas and Germany Salt beds found in Texas and Germany. These are only created in dry tropical areas.

Coal deposits found in USA Coal deposits found in USA. Coal is created in environments similar to the Everglades.

Matching Fossils Plants and animals found on distant lands

Lystrosaurus found on Africa, South America, India, & Antarctica

Evidence for continental drift Matching coastlines Matching folded mountains Matching glacier deposits Salt beds in Texas and Germany Coal beds in West Virginia Matching fossils

Pangaea A Greek word meaning “All-lands” Split apart approximately 200 million years ago (MYBP)

1915 maps by Wegener of Pangaea

Continental drift Theory that continents drift on the surface of the Earth No mechanism proposed No one believed this was possible

Glomar Challenger 1960’s this ship took core samples of ocean floor rocks as it crossed the Atlantic Ocean A map was produced from this data showing the rock types and ages From this map a new theory was developed to explain Wegener’s evidence

Ocean floor rock ages Get older symmetrically away from ridges, the oldest rocks have to be 200,000,000 years old Theory: sea floor splits apart and rocks move away from each other Process: Seafloor spreading Seafloor spreading provides clues to mechanism driving continental drift

Topography of ocean floor

Does sea floor spreading explain everything ? If the Atlantic Ocean is spreading, doesn’t that mean some place is being squeezed together

Recurring patterns in oceans

Plate Tectonics Combining Hutton theory, Wegener’s evidence, Glomar Challenger’s data, and the following world map the present theory of Plate Tectonics came into being Video plates over time

Earthquake and Volcano Distribution Weekly quakes map

Unexpected consequence of continental drift