Plate Tectonics A Brief Overview

The Earth’s Plates

Layers of the Earth ChemicalPhysical

Layers of the Earth and Food Lithosphere –Chocolate: when it’s cold, it’s hard and breaks, but as it warms up it can bend and eventually melt Asthenosphere –Honey: it’s thick and sticky, but it flows Mantle –Crumbled cookies: it’s solid but can move and convect Outer core –Milk: liquid Inner core –Peach pit: solid

Plate Boundaries Stern, R. J., Subduction zones, Rev. Geophys., 40(4), 1012, doi: /2001RG000108, 2002

Margins: Divergent Mid-Ocean Ridges –Mid Atlantic Ridge Continental Rifts –East African Rift Valley vity/cfd-1014_midocean.html nson/m html

Margins: Convergent Ocean-ocean subduction –Island arc: Marianas

Margins: Convergent Ocean-continent subduction –Volcanic arc and mountains: Andes

Margins: Convergent Continent-continent collision –Large mountain range: Himalayas and Alps

Margins: Transform Marine –Transform faults: Mid Atlantic Ridge Terrestrial –Strike-slip faults: San Andreas Fault

Evidence for Plate Tectonics Fit of the continents Sea floor ages and magnetic anomalies – evidence of ocean spreading Paleontology – similar species on now widely separated continents Seismicity and volcanism concentrated at plate boundaries – evidence of oceanic subduction Hot spot tracks – record movement of plates over “fixed” hot spot GPS