Continental Drift & Plate Tectonics Theory

• Success criteria for understanding continental drift and plate tectonics include being able to draw a timeline of events, identify the Earth's structure, describe convection currents, explain the theories, and provide supporting evidence.

Continental Drift and Plate Tectonics Theory

• The theory explains the movement of continents, which were once a single landmass.
• The movement is due to tectonic plates.
• Tectonic plates include the creation of new lithosphere at divergent plate boundaries and the destruction of lithosphere at convergent subduction zones.

Evidence Supporting Continental Drift

• Evidence includes the fit of continents, fossil distribution, climate evidence, and geological formations.
• The evidence supports the idea that continents were once joined.
• Multiple pieces of evidence support each other.

Geological "Fit" as Evidence

• Some parts of Earth seem to fit together like they must have been together in the past.
• The specific parts of continents fit together in shape.

Fossils as Evidence

• The existence of the same fossils found on different continents connects to the idea that they were once together, inhabiting connected landmasses.
• The organisms were unable to cross the ocean.
• The location patterns of the fossils agree with the "geological fit" evidence.
• Examples of such fossils across named continents: Mesosaurus, Cynognathus, Lystrosaurus, and Glossopteris.

Climate Evidence

• Fossils found in places where the current climate would make it impossible for them to exist suggest the land has moved.
• The evidence supports the theory, agreeing with the "geological fit" evidence.
• Examples are Lystrosaurus, and Glossopteris.

Geological Evidence

• Mountain ranges of similar rock age which would align if the continents were once joined, suggesting a connection.
• Examples of such mountain ranges include the Appalachian Mountains of the eastern United States, geologically related to areas in Scotland and Scandinavia across the Atlantic Ocean.
• This evidence agrees with the "geological fit" evidence and supports the theory.

Glacial Evidence

• Glacial evidence in continents that no longer have permanent ice cover suggests they were once joined.
• Glacial features include striations and tills, found in continents like South America, Africa, India, and Australia.
• This agrees with the Geological “fit” evidence
• It connects the southern parts of named land masses.

Bathymetry

• Bathymetry discovered unexpected structures, suggesting the sea floor was not fixed.
• Bathymetry includes the features of deep ocean ridges and trenches.
• These features of deep ocean ridges and trenches are associate with the earthquake and volcanic data.

Seismology

• Seismology led to knowing that the Earth had fluid rock under the crust which allowed the convection to exist and move the plates.
• Boundary types can be identified.
• Deep earthquake epicenters occur at converging plate boundaries, and shallow earthquakes occur at transform plate boundaries.
• Volcanoes are more common at converging plate subduction zones, both are less common at diverging boundaries.

Geology

• Alternating bands of magnetic alignment on either side of the deep ocean ridges suggest the plates move.
• New rock formed at the deep ocean ridge is split and moves away from the ridge, showing the bands being made simultaneously.
• The magnetic poles reverse every 200000 to 300000 years.
• The magnetic parts of the rock are solidified in alignment.

Deep Seabed Sampling

• Thicker sediments and older rock cores were found further from the ridge, showing that the plate is moving.
• The thinner sediment layers are located close to mid-ocean ridges.
• Mid-ocean ridges are younger than the surrounding ocean floor.

Nuclear Physics

• Nuclear physics can determine the age of rock samples.
• Older rocks have a greater proportion of stable isotopes.
• Unstable atoms decay.