Bellringer Go to Mrs. Chapel’s school webpage Open the Earth’s Layers Powerpoint Fill out the cloze worksheet You have 15 minutes to complete this

Continental Drift Continental drift=the gradual movement of the continents across the earth's surface through geological time. Alfred Wegener became the “father of continental drift” by amassing considerable supporting evidence that the continents moved over time.

Alfred L. Wegener Geologist Alfred Wegener noticed similar rocks & fossil remains were found on continents which seemed to fit togetherGeologist Alfred Wegener noticed similar rocks & fossil remains were found on continents which seemed to fit together He called this “super” continent PangaeaHe called this “super” continent Pangaea In 1912 Wegener published the first version & died defending his theoryIn 1912 Wegener published the first version & died defending his theory

Support for Continental Drift 1. SHAPE OF THE CONTINENTS Continents fit together like puzzle pieces

Mesosaurus was incapable of swimming across a large ocean. 2. FOSSIL EVIDENCE SAME FOSSILS: DIFFERENT CONTINENTS Support for Continental Drift

3. ROCK EVIDENCE – Mountain ranges Support for Continental Drift  SAME ROCK: DIFFERENT RANGE Existing mountain ranges separated by vast oceans contain rocks of identical mineral content.  A prime example are the Appalachian Mountains in the eastern U.S and the Caledonian Mountains in the British Isles.  SAME ROCK: DIFFERENT RANGE Existing mountain ranges separated by vast oceans contain rocks of identical mineral content.  A prime example are the Appalachian Mountains in the eastern U.S and the Caledonian Mountains in the British Isles.

SAME SCARS: DIFFERENT CONTINENTS Support for Continental Drift 4. GLACIAL SCARS

5. LOCATION OF COAL DEPOSITS Coal deposits have been found in temperate and polar regions; however, coal is formed in tropical regions. Support for Continental Drift

CONTINENTAL DRIFT IN DOUBT Why didn’t people believe in continental drift? People couldn’t image how the earth could be millions of years old People couldn’t image a force great enough to move the continents BUT by the 1960’s evidence would prove continental drift is TRUE and…. The story continues (as does all good science!)

Go to Gizmos Do the Pangaea Gizmo Ask Mrs. Chapel if you need login help

SEA FLOOR SPREADING Seafloor spreading helps explain continental drift in the theory of plate tectonics. conveyor Ocean floor moves like a conveyor belt carrying continents with it. ocean floor older rocks sea-floor New ocean floor forms along cracks in the ocean crust as molten material erupts from the mantle spreading out and pushing older rocks to the sides of the crack. New ocean floor is continually added by the process of sea-floor spreading.

Sea-Floor Spreading 1. Evidence from Molten Material – Rocks shaped like pillows(rock pillows) show that molten material has erupted again and again from cracks along the mid-ocean ridge and cooled quickly

Sea-Floor Spreading 2. Evidence from Magnetic Stripes – Rocks that make up the ocean floor lie in a pattern of magnetized stripes which hold a record of the reversals in Earth’s magnetic field

Sea-Floor Spreading

3. Evidence from Drilling Samples – Core samples from the ocean floor show that older rocks are found farther from the ridge; youngest rocks are in the center of the ridge

Sea-Floor Spreading 8. Subduction – Process by which the ocean floor sinks beneath a deep- ocean trench and back into the mantle; allows part of the ocean floor to sink back into the mantle

Sea-Floor Spreading: Subduction zone Deep-Ocean Trench – Occurs at subduction zones. Deep underwater canyons form where oceanic crust bends downward

Closure Complete the worksheet side about continental drift and seafloor spreading Put the worksheet in the basket