Class 1 Plate Tectonics Essay

Submitted By MarkMacio1995
Words: 403
Pages: 2

Earth Sciences 1022b Lecture Brief 8 Jan 15
Why? Geology (study of Earth) is important for energy and natural resources, solving environmental problems, building cities and highways, predicting and protecting against natural disasters like earthquakes, volcanic eruptions, landslides, floods
Uniformitarianism: fundamental principle “the present is the key to the past”
How long? geologic time is measured in billions of years
Where and How? After the Big Bang (~14 billion years ago) Earth may have formed by the nebular theory: ~5 billion years ago a solar nebula of hydrogen and helium gravitationally contracted into a rotating disc with our Sun at the centre, and the planets and moons revolving around it

within the disc, Earth evolved through many collisions of rocky and metallic fragments into a rocky sphere divided into a dense core, large mantle, and lighter crust

Plate Tectonics: the crust and uppermost mantle eventually split into rigid plates of lithosphere (sphere of rock) that move over Earth’s surface above the soft, convecting asthenosphere (weak sphere) by Continental Drift, based on... fit of the continents - e.g. South America, Africa and other continents fit well together at
900 m depth which coincides with the edge of their continental shelves fossil evidence - same type and age found on continents separated by ocean basins rock types and structural similarities - match when continents are fit back together paleo climates - evidence of ancient glaciations in warm areas of today - show the pattern of a single ice sheet if continents are refitted back together; also, ancient coal