Plate Tectonics Outline v Pangaea v Continental Drift

Plate Tectonics

Outline v Pangaea v Continental Drift v Mid-ocean ridges and seafloor spreading v Magnetic patterns on the seafloor v Plate tectonics: map of plates and theory v Plate boundaries

Pangaea Means “all lands” v Name given to the single landmass composed of all the continents v Idea developed by Wegener v Pangaea broke apart into 7 continents (200 MYA): Continental drift v

Continental Drift: Evidence v v v Fossils Rock type Paleoclimates Fit of coastlines Structural similarities

Rock Type

Paleoclimate

Rejection of theory v Continental drift was not accepted initially v Wegener believed that continents moved through the ocean: FALSE v Continents and oceans actually move together! v Wegener could not explain WHY the plates move

Mid-ocean ridges discovered in early 1960 s v Mountain ranges on the ocean floor v Discovered using echo sounders v

Mid-Atlantic Ridge

Seafloor spreading occurs at MORs v Sea floor on either side of the ridge pushed away by rising magma from the mantle v

Magnetic patterns on the seafloor Earth’s magnetic polarity reverses v The magnetism is trapped in the rocks at the spreading center when rocks cool v Creates a pattern on the seafloor v

Plates are pieces of the lithosphere

Putting it all together v Magnetic patterns v Seafloor spreading v Continental drift v Lithosphere divided into plates

How does it happen?

Types of boundaries

Why is this important? Most geologic activity occurs at plate boundaries v Volcanoes, earthquakes, tsunamis v