EQ: How do lithospheric plates move and how do they affect the Earth’s surface?

 In 1912, Alfred Wegener proposed the idea of Continental Drift  He suggested that all of the continents were once joined together to form a supercontinent

 Wegener called this super landmass Pangaea and believed that it broke apart 200 million years ago  Pangaea means “all land”  At first, his theory was not accepted  Unable to explain how the continents drifted apart

 Years later came important observations that supported Continental Drift 1. Fossil Clues- similar fossils found in South America and Africa and others found in Africa, Australia, India, South America, and Antarctica.

2. Rock evidence- similar rock structures are found on different continents, such as this mountain belt that end at one coastline, only to reappear on a landmass across the ocean.

3. Climate Clues- glacier deposits and rock surfaces shows that parts of South America, Africa, India, and Australia were once covered with glaciers

1. What is Continental Drift? 2. What 3 pieces of evidence support the idea of Pangaea? The idea that all of the continents were once joined together Fossils, Rock Clues (Mountains), and Climate Clues (Glaciers)

 Wegener could not provide an explanation of exactly what made the continents move. plate tectonics  New technology lead to findings which then lead to a new theory called plate tectonics

 With new technologies, scientists discovered a mountain chain on the ocean floor known as the Mid-Ocean Ridge  Mid-ocean ridges are underwater chains that run through Earth’s ocean basin The Mid-Atlantic Ridge, the longest mountain chain in the world

 Mid-ocean ridges are places where the sea- floor spreads  As tectonic plates move away from each other, the seafloor spreads apart and magma rises to fill in the gaps  The hot magma contacts ocean water, cools and hardens becoming new rock Seafloor Spreading  This process is known as Seafloor Spreading

Plate Tectonics  The Theory of Plate Tectonics was developed in 1960s and combines the theories of Continental Drift and Sea-Floor Spreading. plates  Scientist believe the Earth’s crust and part of the upper mantle is broken into 13 sections that make up the plates which move on top of the asthenosphere

 Convection currents, originating deep within the mantle, provides the energy that drives plate tectonic  These currents rotate in circular patterns, carrying heat upward k=12p&att=2775

 Divergent boundaries are the place where two plates move apart.  Convergent boundaries form where two plates move together.  Transform fault boundaries are where two plates slide past each other without the production or destruction of the lithosphere.

1. Explain why Wegener’s theory of Continental Drift was not accepted at first. 2. Explain what is Plate Tectonics and what causes the movement of plate tectonics. 3. What are the 3 plate boundaries and describe them.