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Introduction to Plate Tectonics

Introduction to Plate Tectonics

Introduction: The ground under our feet feels rock solid. Yet, it is in motion. As early as the 1500s, it was suspected that the continents were moving. However, it wasn't until the early 1900s when scientist Alfred Wegener pieced together evidence and proposed the theory of continental drift. His theory stated that the continents were once one supercontinent. Over time, it broke apart and moved into the positions of today’s continents. Wegener's theory was widely rejected until the mid-1900s when sonar mapping of the ocean floor showed evidence of seafloor spreading. This finding helped advance the theory of continental drift to our modern day theory of plate tectonics.
The theory of plate tectonics states that Earth's solid lithosphere is made of plates that float on the asthenosphere. 
The map below shows the major tectonic plates:

Tectonic Plates With Labels

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