Evidence for continental drift
- Created by: EEC2145
- Created on: 11-01-23 12:31
View mindmap
- Evidence for continental drift
- Modern evidence
- Mantle tomography
- We have images of the mantle moving based off earthquake waves.
- Discovered 1960s.
- Paleomagneti-sm
- New volcanic rock (basalt) is formed at the ridge, when cooled it magnetises.
- The crystals rotate and align with the current field allowing the age to be found
- Discovered by magnetic surveys in the 1960s
- Lead to Vine and Matthews proposing the theory of sea floor spreading
- Age of rocks in the Atlantic
- Maurice Ewing discovered the Mid-Atlantic Ridge in 1948
- Harry Hess dated the rocks in 1962.
- Locations of volcanoes and earthquakes
- They mainly follow Earth's tectonic plate boundaries where the plates meet
- GPS tracking
- GPS receiver pins are dropped on the ocean floor and plates can be watcher moving in real time.
- 1990s-2000s
- GPS receiver pins are dropped on the ocean floor and plates can be watcher moving in real time.
- Mantle tomography
- Wegner's evidence 1912
- Continental fit and matching geology
- Rocks of similar age, type and formation are found in Southeast Brazil and Southern Africa
- The continents fit together like a puzzle
- The best fit is 1000m below sea level with South America and West Africa
- Coal deposits are found in North America, UK, Northwest Eurpoe and Antarctica.
- Coal can only form in warm, wet conditions yet not in current locations
- North America and Europe have mountain ranges that match up when pushed together (Appalachians with belts in Europe and the UK)
- Geology of Eastern South America and West Africa was mapped to reveal ancient rock outcrops (cratons) over 2000 million years old were continuous from one to the other
- Animals and Plants
- Many examples of fossils are found on separate continents and nowhere else
- Mesosaurus (freshwater crocodile-like creature) (286-258 million years ago)
- Solely found in Southern Africa and Eastern South America.
- Would have been physiologically impossible for them to swim the Atlantic
- Glossopteris (woody, seed-bearing shrub or tree)
- 299 million years ago
- Found in Australia, South Africa, South America, India and Antarctica
- Embedded in the same layer sequence but each continent has a different climate now
- Mesosaurus (freshwater crocodile-like creature) (286-258 million years ago)
- When the continents of the Southern hemisphere are re-assembled into the single land mass on Gondwanaland
- Many examples of fossils are found on separate continents and nowhere else
- Past glaciations.
- Present day tropical locations show evidence of past glaciations
- These must have been in a different location previously
- Glacial deposits formed 300 million years ago are found across the Southern hemisphere
- These must have been in a different location previously
- Glacial striations (scratches and gouges from glacial abrasion) found in African deserts
- Glacial deposits formed 300 million years ago are found across the Southern hemisphere
- Present day tropical locations show evidence of past glaciations
- Continental fit and matching geology
- Modern evidence
Comments
No comments have yet been made