Lesson 3 Flashcards
When did Wegener publish his theory of continental drift?
1915.
How did Wegener come up with his theory of continental drift?
Used his map of Pangea and found fossils and rocks on different continents where similar.
How was glacier evidence used?
300 millions years ago glaciers covered the southern hemisphere which doesn’t make sense unless they’re all together at once and the flow of glaciers fit with how they move.
What happened in WW1 to support his theory more?
Sonar technology developed which revealed geologic details about the ocean floor.
What happened in 1919?
Arthur Holmes discovered that land masses (plates) move by convection currents in the mantle, they could lift the crust sideways and move it.
What was discovered in 1946?
Mid-Atlantic Ridge by using sonar technology.
What happened in 1954?
Volcanoes found on plate boundaries but some found on the centre of plates. (pacific ring of fire evidence).
What theory was developed in 1960?
Sea floor spreading - magma oozes up from mid ocean ridges which creates a new sea floor.
What happened in 1963?
Magnetic rock, earth has a magnet in its core creating north and south poles which reverses every 200,000 years.
What happens in 1965?
Wilson proposes that the earths crust is made of giant chunks of rock called plates which supports the theory of plate tectonics.
What is made available to the public in 1983?
GPS which is able to track the movements of the earths surface in CM.
How were convection currents discovered?
Seismic waves
