Plate Tectonic Theory Flashcards
•Outline the early theory by Alfred wegener •Recall the geological and biological evidence •know how the theory was developed (1940's onwards) •Outline sea floor spreading and palaeomagnetism •outline the process of subduction
Who is Alfred Wegener (1880-1930) and what did he do?
Alfred Wegener was a meteorologist who hypothesised that the continents were once joined together as one supercontinent called Pangea. This landmass was then broke apart due to plate tectonic theory and each continent was split up into its current position.
What geological evidence has been presented?
- Scotland and Canada have the same type and age of rock
- Jigsaw theory suggests that we can see the shape of each join in the supercontinent. Eg- Papua New Guinea and Australia. South America and Africa. Australia and Antarctica.
What biological evidence has been presented?
Fossil remans of the same animal can be found on different continents. Genetically similar animals live today on different continents such as New Zealands kiwi, Africa’s ostrich and Australias emu
Developments of the theory. (1940s onwards)
Tazo Wilson believed the plates move over fixed ‘hotspots’
What is sea floor spreading and palaeomagnetism?
|↑|↓|↑|↓||↓|↑|↓|↑| |↑|↓|↑|↓||↓|↑|↓|↑| |↑|↓|↑|↓||↓|↑|↓|↑| |↑|↓|↑|↓||↓|↑|↓|↑| What is shown above is either side of the ridge such as the mid Atlantic ridge equidistant rock shows that the direction of ferrous material points towards the north pole for its time. As the poles switch and new rock is made the direction changes.
What is subduction?
Subduction is when soft oceanic crust is subducted by hard continental crust at a plate boundary. This oceanic crust is melted into magma and rises through cracks in the continental crust to make volcanoes.
