Evidence of Continental Drift
Alfred Wegener supported his theory of continental drift with several pieces of evidence.
Evidence in the Fossil Record:
- In the fossil record of several continents, groups of plants and animals showed a simultaneous, orderly evolution.
- At some point in time their evolutionary paths diverged.
- Paleontologists found fossils of some plants and animals that seemed to have an odd pattern of distribution.
- Species of ancient land plants and animals were found to span modern day oceans.
- Continental drift provides a reasonable way to explain this distribution of species and the 'sudden' change of evolutionary paths.
Rock Strata Evidence:
- Wegener observed that rocks in Eastern Brazil matched those of northeastern Africa.
- The types of rocks, the age of the rocks and the patterns (or layering) of types of rocks matched.
- Mountainous ranges of similar structure and composition exist in eastern North America, Britain and Scandinavia.
- These mountainous areas line up to form a continuous band when the continents are assembled to form Pangaea.
- The old mountain ranges were formed on ancient Pangaea and subsequently torn apart when Pangaea broke up.
Evidence from Paleoclimates:
- The continents of the southern hemisphere show evidence of glaciation.
- The tell-tale striations that glaciers leave as they scrape across bedrock were confusing.
- It appeared as if there were glaciers at the equator and glaciers coming from the sea onto the land!
- These striations and glacial deposits are consistent with a Pangaean glaciation at the South pole.
- Corals are small animals that build up their homes from calcium carbonate (CaCO3) found in sea water.
- Large colonies of corals create vast reefs.
- Coral will live only in warm water, but ancient coral reefs are found in Europe and North America.
- Coal is the remains of swamp plants accumulating over eons, being buried and then compressed by overlaying rock.
- Vast coal fields exist in cold areas such as North America, Antarctica, and Siberia!