Images from Ruddiman, Chapter 4, Plate Tectonics and Long-Term Climate

From 550 million years ago

PURPOSE OF THIS STUDY: To understand the role of tectonics and location of continental masses in the periodic global cooling periods, glaciations

Periods of glaciation have been fairly rare in earth's history -- this diagram shows only the past 550 million years

 

Plate Tectonics:

 

About a dozen crustal plates float on the plastic mantle of the lithosphere, slowly moving around and colliding with each other

 

Types of divertent and convergent plate margins --

Subduction zones -- where plates collide

Spreading zones -- most commonly in ocean basins, create volcanoes, earthquakes

Oceanic-oceanic convergent zones -- create volcanic island arcs, earthquakes

Oceanic-continental convergent zones -- create mountains, volcanoes, earthquakes

Continental-continental convergent zones -- create mountains, high plateaus, earthquakes

Transform fault zones -- where plates slide past each other -- create earthquakes

Hot spots -- randomly located, related to stationary zones of upwelling magma -- volcanoes, earthquakes

 

PALEOMAGNETISM

 

Provides evidence of the latitudinal location of a rock at time of formation, as molten magma