4 Continental Drift Theory Proposed by Alfred Wegener in 1912250 million years ago, all of the continents were combined into one super-continent called “Pangaea”The continents gradually drifted apart to where they are today
5 “Puzzle Pieces”Continents look like they could be part of a giant jigsaw puzzle
6 Distribution of Fossils Plant and animal fossils found on the coastlines of different continents
7 Ancient ClimatesTropical plant remains (coal deposits) found in AntarcticaGlaciation in Africa, South America, India, and Australia during the same time
8 Sequence of RocksSame rock patterns found in South America, India, Africa, Antarctica and Australia
9 Problems With The Theory Theory was not accepted by scientists…why?Because Wegner could not identify the cause of continental drift
41 IntroductionTube Worms - live in the Pacific Ocean about one mile deep near the hydrothermal vents.
42 Mapping the mid-ocean ridge The East Pacific Rise has a mid-ocean ridge.Curves around like a baseball.Lies hidden under hundreds of meters of water.
43 SonarA device that bounces sound waves off underwater objects and then records the echoes of these sound waves.Sonar mapped mid-ocean ridges.
44 Harry Hess An American geologist who studied mid-ocean ridges. He suggested that the ocean floors move like conveyor belts, carrying the continents along with them.
45 At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. As the molten material cools, it forms a strip of solid rock in the center of the ridge. Then more molten material flows into the crack.
46 Sea-floor spreadingThe process that continually adds new material to the ocean floor.Evidence molten material, magnetic stripes, and drilling samples.
47 EvidenceMagnetic Stripes. How does the pattern of matching stripes show evidence of sea-floor spreading?
48 Evidence #3 - Drilling Samples The Glomar Challenger did a drilling sample and found rocks that the farther away from the ridge the older the rocks were. The younger ones were in the center of the ridge.