EESA06H3 Lecture Notes - Lecture 2: Continental Drift, Leading Edge, Eurasian Plate
Document Summary
Plate tectonics- continents are embedded into larger plates and it s the plates that move. First maps started to appear when trade started to increase. Waegner (1912)- first suggestion that continents might fit together. Craters on the move are a result of impact not volcanic. Its been subducted (recycled back into the mantle) Water gets heated above boiling point and then scavenges. Formed when na was close to the equator. Laurentia- refers to north america in ancient past. When waegner died people started to think that the earth contracted. He looked at rock times of the same age on different continents and they matched. Continents migrated from area with ice sheets into tropical areas. Mid-ocean ridges- about 65 000 km long- shallow, weak earthquakes. Cold sea water penetrates the rocks through cracks and crevasses (temperature increases the deeper you go) (picks up stuff) minerals from the rocks (gold, silver) those minerals in the rocks are present in low concentration.
