Continental Drift and Plate Tectonics Flashcards
Theory of Continental Drift
Alfred Wegener, in 1915, came up with the idea of Continental Drift.
He said that the continents of the Earth slowly moved. He said they used to be one big continent (pangaea) a long time ago, but split apart and moved to where they are today.
Wegener’s Proof
4 pieces of evidence for his theory (idea) were:
Rocks that were the same age and type
The shape of the continents (look like puzzle pieces that fit together)
Fossils that were the same
Past climate data
Theory of Plate Tectonics
This theory (idea) was made by J. Tuzo Wilson in 1968.
He said that the Earth’s crust is made up of many plates and that these plates move on top of the mantle. The movement of the plates causes changes to the Earth’s surface.
The Plates
Plates are pieces of the Earth’s crust.
The plates that move are both continental and ocean plates.
The Earth’s crust is divided into 12 major plates.
Heat from deep inside the earth causes plates to move
Earth’s continents sit on plates, so when the plates move, the continents move with them
The movement is called…
Plate Tectonics
On average, the plates move about…
as fast as fingernails grow/an inch or so every year
Plates are pieces of the Earth’s crust. The plates that move are…
both continental and ocean plates.
Plates move constantly, and when they move different things happen…
They can collide, pull apart, or scrape against each other.
Each type of movement causes changes on Earth’s surface… structures or “tectonic” features (ex. Mountains, volcanoes).
The word, tectonic, refers to
the distorting of the crust as result of plate interaction.
Plates move because of
Convection Currents
The mantle is made of much denser, thicker material, because of this the plates
“float” on it like oil floats on water.
Movement of plates is caused by
very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over
