Plate Tectonics A Giant Jigsaw Puzzle and Continental Drift https://youtu.be/1-HwPR_4mP4

Tectonic plates review Tectonic Plates: a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle What type of crust… Continental Crust Oceanic Crust Both

Major Tectonic Plates: Memorize!! Pacific plate North American plate Cocos plate Nazca plate South American plate African plate Eurasian plate Indian plate Australian plate Antarctic plate

Tectonic Plate Close-up Consist of upper part of mantle Oceanic Crust (thinnest) Continental crust (thickest) **Remember that the lithosphere and asthenosphere make up the upper part of the mantle and the crust.

Wegener’s Continental drift Hypothesis Alfred Wegener 1900s Hypothesis about continental drift

Continental drift Continental Drift: the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations Explains why fossils of the same plant and animal species are found on continents across oceans

The drifting continents Pangaea Wegener hypothesis that all of the present continents were once joined in a single, huge continent Greek for “all earth” Existed 245 million years ago Split into 2 continents Laurasia and Gondwana 180 million years ago Split again into the continents of today North America South America Asia Europe Australia Antarctica Africa Wegener's hypothesis was not accepted by many scientist. It wasn’t until many years later that evidence provided some clues to the forces that moved the continents.

More Evidence: Sea floor spreading Sea Floor Spreading: the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies. Chains of submerged mountains run through the center of the Atlantic Ocean. Mid-ocean ridge system As the tectonic plates move away from each other, the sea floor spreads apart and magma fills in the gap. As this new crust forms, the older crust gets pushed away from the mid-ocean ridge. Magnetic reversals recorded in the ocean floor, throughout history, the north and south magnetic poles have changed places many times.

More Evidence: Magnetic reversals Magnetic reversal: when the Earth’s magnetic poles changes The molten rock at the mid-ocean ridges contains tiny grains of magnetic minerals such as iron. These minerals act like compasses and align with the magnetic field of the Earth. When the molten rock cools, the record of these tiny compasses remains in the rock. As the sea-floor spreads the record is slowly carried away from the center.

Student task Elbow Partners: Create a puzzle piece for each continent. See how many ways the continents can fit together https://youtu.be/Kg_UBLFUpYQ