Clues in the CrustClues in the Crust

Need To Know Need To Know Background InformationBackground Information The formation of Mountains is a slow The formation of Mountains is a slow

movement of Earth’s Crust where movement of Earth’s Crust where earthquakes and volcanoes are much earthquakes and volcanoes are much more rapid and violent. more rapid and violent.

Scientist can explain both types of Scientist can explain both types of movement by studying cross sections of movement by studying cross sections of the sea floor. the sea floor.

A A cross sectioncross section is a drawing of what you is a drawing of what you see when you cut through an object. see when you cut through an object.

Ocean Floor MorphologyOcean Floor Morphology

Ocean RidgeOcean Ridge – the raised floor, which can – the raised floor, which can become large enough to be considered an become large enough to be considered an underwater mountain range. ie Juan de Fuca underwater mountain range. ie Juan de Fuca RidgeRidge

Continental Slope Continental Slope – a deep slope in the – a deep slope in the seabed between a continental shelf and the seabed between a continental shelf and the sea floor. sea floor.

Continental Shelf Continental Shelf – a shallow underwater – a shallow underwater ledge located between a continent and the ledge located between a continent and the deep ocean. deep ocean.

Cross section

Abyssal PlainAbyssal Plain – a large flat area on the – a large flat area on the sea floor. Abyssal plains make up a large sea floor. Abyssal plains make up a large part of the sea floor. part of the sea floor.

RiftRift – an opening in the oceanic crust, – an opening in the oceanic crust, where molten materials from Earth’s where molten materials from Earth’s mantle can escape. mantle can escape.

Cross section

How Does Earth’s Crust How Does Earth’s Crust Move?Move?

A scientist who searched for answers A scientist who searched for answers was a German Meteorologist (studies was a German Meteorologist (studies climate and weather), Alfred Wegener climate and weather), Alfred Wegener (1880- 1930). Wegener noticed that the (1880- 1930). Wegener noticed that the continents almost fit together like a continents almost fit together like a puzzle. puzzle.

PangaeaPangaea

Wegener thought that the fit of the Wegener thought that the fit of the continents was more than just a continents was more than just a coincidence. He suggested that all the coincidence. He suggested that all the continents were joined together in a huge continents were joined together in a huge land mass called Pangaea. He land mass called Pangaea. He suggested that Pangaea broke apart suggested that Pangaea broke apart about 200 million years ago. about 200 million years ago.

Another Theory from Another Theory from WegenerWegener

Wegener also proposed the theory of Wegener also proposed the theory of continental drift. According to the continental drift. According to the theory of theory of continental driftcontinental drift, the continents change , the continents change position very slowly, moving over the surface of position very slowly, moving over the surface of Earth a few centimeters every year. Earth a few centimeters every year.

Most of the scientists of Wegener’s time Most of the scientists of Wegener’s time strongly disagreed with him. Wegener could strongly disagreed with him. Wegener could not explain how the continents moved but not explain how the continents moved but collected as much evidence as he could. He collected as much evidence as he could. He collected fossils and rocks. collected fossils and rocks.

As Wegener looked more carefully at the As Wegener looked more carefully at the climates suggested by the fossils and geology climates suggested by the fossils and geology in different areas, he saw unexpected in different areas, he saw unexpected similarities between continents that are no similarities between continents that are no longer close together. He and Vladimir Koppen longer close together. He and Vladimir Koppen marked all the climates on the continents and marked all the climates on the continents and then tried to put the continents together based then tried to put the continents together based on their paleoclimatic evidence. They found on their paleoclimatic evidence. They found the continents fit together like a puzzle. the continents fit together like a puzzle. Wegener based his theory of continental drift Wegener based his theory of continental drift on biological, geological and meteorological on biological, geological and meteorological evidence.evidence.

Fossil EvidenceFossil Evidence

Fossils of the reptile Mesosaurus have been found in Fossils of the reptile Mesosaurus have been found in South America and Africa. Mesosaurus lived in fresh South America and Africa. Mesosaurus lived in fresh water and on land and probably could water and on land and probably could not swim between not swim between continents. continents. Wegener Wegener hypothesized that hypothesized that this reptile lived on this reptile lived on both continents when both continents when they were joined. they were joined.

Evidence From RocksEvidence From Rocks

The Appalachian Mountains in eastern The Appalachian Mountains in eastern North America are made of the same North America are made of the same kind of rock as a mountain range in kind of rock as a mountain range in Britain and Norway. There are similarities Britain and Norway. There are similarities between rock in Quebec and rock in between rock in Quebec and rock in northern Britain. There are also northern Britain. There are also similarities between rock in South similarities between rock in South America and rock in Africa. America and rock in Africa.

Rock EvidenceRock Evidence

Modern Day EvidenceModern Day Evidence

Technological advances have allowed Technological advances have allowed geologists to actually touch the sea floor geologists to actually touch the sea floor sediments that were found over 1000m sediments that were found over 1000m deep.deep.

Scientists have used Sonar, Seismic Scientists have used Sonar, Seismic Waves and Core Samples to confirm Waves and Core Samples to confirm Wegener’s theory of continental drift.Wegener’s theory of continental drift.