Plate Tectonic Theory Flashcards
What does the theory of plate tectonics help us to understand?
The distribution of the worlds major landforms.
Where natural hazards can strike.
The distribution of minerals and energy supplies.
Scientists now know that the Earth’s outer shell is composed of what?
16 plates.
Many plates include areas of both land and ocean.
Continuously in motion.
What did scientists believe 300 million years ago?
That there was one big super continent named pangaea.
What was discovered in the 16th century?
That the coastline of the continents showed a remarkable conformity.
Francis Bacon one of the first scientists to recognise that continents could be fitted together - single super continent.
What did Alfred Wegener do?
geologist in Germany
In the 20th century introduce the idea of continental drift
What did Wegener realise?
The continents of world fitted together like jigsaw puzzle.
He found that in the Carboniferous age some 250 millions years ago, until some time in the Pleistocene about 1 million years ago a single continent called Pangaea slowly broke up and drifted apart.
Name evidence which supported Alfred Wegeners theory?
Rare fossils found i rocks of different continents, now separated by thousands of km of ocean.
Glaciations, which affected different areas become contiguous if the continents are fitted back together.
Rocks/mountain ranges, fold belts all consistent.
However, when were doubts addressed in Wegeners theory and what about?
In the 1960s - 1970s when the sea floors were studied, about the mechanisms of the break up.
What happens when volcanic rocks cool?
They adopt a magnetic field which reflects that of the Earth’s magnetic field.
