Fundamental Principles for Understanding Earth History
Earth System Components
Earth’s Basic Structure
The Principle Of Uniformitarianism: "The present is the key to the past"
Modern scientists believe that the physical laws of nature have not changed over the course of time. Therefore, processes we observe today can be applied to events of the past or even the future.
Modern Alaskan glacier and glacial deposits in Ohio
Earth’s Internal Structure
Modern tectonic plates: Note the location of numerous volcanoes. Earthquakes are also found concentrated at these boundaries.
Plate Tectonics = Process by which lithospheric plates move.
Rising heat produce convection currents that converge driving plates together. Where convection currents diverge, this pushes the plates apart.
Types Plate Boundaries
Convergent plate boundaries: See examples below
Convergent Plate Boundaries: Subduction Zones
A process called subduction drives one plate into the mantle. Melting occurs generating magma which buoyantly rises forming volcanoes. In the case of continent – continent collision the crust is thickened, major mountain building occurs.
Convergent Plates: Ocean - Ocean Collision
Convergent Plates: Ocean-Continent Collision
Convergent Plates: Continent-Continent Collision
Crust thickens, extensive faulting occurs that regional uplifting and mountain building
Divergent plate boundaries
Divergent Plates: Mid-ocean Ridge
Divergent Plates: form with continents are called Continental Rifts
Transform Fault Boundaries
Summary of Tectonic Boundaries