Plate Tectonics Flashcards
Who invented the theory of continental drift ?
In 1912, Alfred Wegener proposed his theory of continental drift:
The world’s first super continent called ?
Pangea
Evidence which supports the continental drift theory include ?
Jigsaw fit
Distribution of fossil evidence - the same type of fossils ( being located thousands of kilometres apart on separate continents.
What is seafloor spreading ?
The process of new rocky crust being formed at ocean ridges proposed by Harry Hess
What is magnetic striping ?
Magnetic striping is the pattern of alternating magnetic anomalies on the ocean floor, formed by reversals of Earth’s magnetic field as magma solidifies at mid-ocean ridges. This creates symmetrical stripes of normal and reversed polarity, providing evidence for seafloor spreading and plate tectonics.
Age of the seafloor
The age of the seafloor is the time since oceanic crust formed at mid-ocean ridges. It is youngest near the ridges and older farther away,
What is the asthenosphere ?
Tectonic plates float on a layer of semi-liquid rock in the upper mantle
Gravitational forces ?
The movement of the Earth’s plates are due to convection currents in the Earth’s mantle and gravitational forces.
How many major plates are there ?
7
Where is oceanic crust found ?
found on the ocean floor (below sea level)
Where is continental crust formed ?
continental crust form the continents (above sea level).
Oceanic Crust vs Continental crust
Oceanic crust is much thinner than continental crust, and more dense.
Three ways Tectonic plates move ?
Diverging boundaries - plates move apart
Converging boundaries - plates collide with each other
Transform boundaries - plates slide against each other
What is a volcano ?
a place where extremely hot material from inside the Earth (i.e. ash, lava, gas, and lumps of rocks) erupts at Earth’s surface.
How are volcanoes formed ?
form where molten rock called magma has accumulated below weak spots in the Earth’s crust and is pushed upwards under great pressure.
