Theory of Continental Drift and Theory of Plate Tectonics * Essential Questions * What were points of contention with the Theory of Continental Drift? How did the Theory of Plate Tectonics affirm the Theory of Continental Drift?

Mosquito Creek Warm Up: What information can you gather from the Mosquito Creek cartoon?

Theory of Continental Drift Proposed by Alfred Wegener States that the continents were once joined to form a supercontinent Named the continent Pangaea- all land

Continental Drift Supporting evidence – Continental Puzzle – Matching Fossils – Rock Types and Structures – Ancient Climates

Continental Drift Continental Puzzle – Similar coastlines on opposite sides of South Atlantic Ocean Counter Argument – Similar coastlines due to erosion

Continental Drift-Evidence Matching fossils – Fossils of same species found on different continents – Exp. Mesosaurus found in South America & Southern Africa Counter Argument – Land bridges which occurred during glacial period

Continental Drift-Evidence Rock Types & Structures – Mountain belts occur on multiple continents – Exp. Appalachian Mountains

Continental Drift-Evidence Ancient Climates – Glacial evidence in southern Africa and South America – Large tropical swamps in Northern Hemisphere Coal fields in eastern US, Europe, and Siberia Counter Argument – Earth was very cold

Continental Drift Major problem – No mechanism of continent movement – Hypothesis rejected X

Plate Tectonics Mechanism of continent movement Solution came from seafloor mapping data States: Earth’s crust is divided into distinct plates that float on molten interior -> continents move as plates move

Plate Tectonic Theory 13 different plates Supporting Evidence – Paleomagnetism – Earthquake Patterns – Ocean Drilling – Hot Spots

Plate Tectonic Theory-Evidence Paleomagnetism – Rocks containing iron- rich minerals are magnetized – Point towards the magnetic pole of creation – Strips of alternating polarity occur at ocean floor -> seafloor spreading

Plate Tectonic Theory-Evidence Earthquake Patterns – Along ocean trenches 1.Shallow focused earthquakes occur within trench/where descending plate interacts with lithosphere 2.Deep focused earthquakes occur toward mainland/ when oceanic lithosphere plunges into mantle

Plate Tectonic Theory-Evidence Ocean Drilling – Sediment closer to ridges will be younger – Sediments farther away will be older Sediment age increasing

Plate Tectonics-Evidence

Plate Tectonic Theory-Evidence Hot Spots – Rising plume of mantel material – Melting of rock at/near surface -> volcanics – Plate moves creating successive volcanic mountains/chains

Recap 1.The Theory of Continental Drift explains movement of continents over time 2.Theory of Plate Tectonics provides mechanism for movement. 3. Supporting evidence: C-DriftP-Tectonics Continental PuzzlePaleomagnetism Matching FossilsEarthquake Pattern Rock Types and Structures Ocean Drilling/Ages Ancient ClimatesHot Spots