Continental Drift We know the Asthenosphere is a solid that can move and flow….also called a Non Newtonian fluid Who came up with the Theory of continental drift? • Alfred Wegener (Vegner) was a German scientist. • He gave the theory that Earth’s continents have moved. • It is the idea or Theory • that all the continents were once joined together in a single landmass and have since drifted (moved) apart slowly. . http://education-portal.com/academy/lesson/alfredwegeners-theory-of-continental-drift.html#lesson https://www.youtube.com/watch?v=MEh4B 1Pv8YE Wegener’s Theory of Continental Drift: • All continents had once been joined together in a single land mass (supercontinent - PANGAEA) and later began to drift apart. • Pangaea - The name of the single landmass that broke apart 200 million years ago and gave rise to today’s continents. Pangaea (Supercontinent) Sit very still! • Can you feel the North American plate moving? • It was a pretty radical idea at Wegener’s time to say the continents were moving. • Most scientists were skeptical. • However, Wegener had evidence….. Wegener’s 3 main pieces of evidence: 1. LandformsShapes of the Continents – They appeared to ‘fit’ South America and Africa. Coal Fields - In North America and Europe match up when pieced together (also ‘fit’ as well) Mountains and Rock Layers – In North America and Europe match up when the continents are pieced together (similar rocks) Wegener’s 3 main pieces of evidence: 2. Fossil Evidence - Fossils of the same animals were found on many different continents, now separated by oceans: Glossopteris = plant Cynognathus = land reptile Lystrosaurus = land reptile Mesosaurus = freshwater reptile These organisms had no way to travel across such oceans that exists today! • Also, fossils of the Glossopteris (a fern) have been found in rocks of Africa, South America, Australia, India, and Antarctica! • Finding these fossils on such widely separated landmasses, convinced Wegener that the continents had once been united. Wegener’s 3 main pieces of evidence: 3. Climate Evidence – Tropical Plants - Found in areas that are considered Arctic (frozen) today. Glaciers - Evidence of glaciers found in areas that have temperatures far too mild to have glaciers. Evidence shows that climate must have been much different in the past So why didn’t Wegener’s fellow scientists accept his theory? • He was missing one key point to support his theory? • Wegener could not provide an explanation for the force that pushes or pulls the continents.