Theory of Continental Drift The Present is the Key to the Past

James Hutton 1785 Uniformitarianism Known as the father of geology

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

Evidence for continental drift Matching folded mountain Ranges (Atlas, Appalachians, and Scandinavian Highlands)

Evidence for continental drift Matching glacier deposits

Evidence for continental drift Salt beds found in Texas and Germany. These are only created in dry tropical areas. Salt beds found in Texas and Germany. These are only created in dry tropical areas.

Evidence for continental drift Coal deposits found in USA. Coal is created in environments similar to the Everglades. Coal deposits found in USA. Coal is created in environments similar to the Everglades.

Evidence for continental drift Matching Fossils (Lystrosaurus)

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

Pangaea A Greek word meaning “All-lands” A Greek word meaning “All-lands” Split apart approximately 200 MYBP Split apart approximately 200 MYBP

1915 maps by Wegener of Pangaea

Continental drift Theory that continents drift on the surface of the Earth Theory that continents drift on the surface of the Earth No mechanism proposed No mechanism proposed No one believed this was possible 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 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 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 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 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 Theory: sea floor splits apart and rocks move away from each other Process: Seafloor spreading Process: Seafloor spreading Seafloor spreading provides clues to mechanism driving continental drift Seafloor spreading provides clues to mechanism driving continental drift

Topography of ocean floor

Does sea floor spreading explain everything ? Does sea floor spreading explain everything ? If the Atlantic Ocean is spreading, doesn’t that mean some place is being squeezed together 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 Combining Hutton theory, Wegener’s evidence, Glomar Challenger’s data, and the following world map the present theory of Plate Tectonics came into being

Earthquake and Volcano Distribution Weekly quakes

Unexpected consequence of continental drift