Plate Tectonics is Accepted

After WWII data accumulated rapidly from the oceans

Paleomagnetic data (ancient magnetic poles) indicated that continents had moved over millions of years

Magnetic anomalies (stripes) in the oceans showed that new seafloor was created at mid-ocean ridges (seafloor spreading)

Earthquake locations showed that plates were descending into mantle at ocean trenches

Convection proposed as driving mechanism

Still controversial in 1964, global plate tectonics was accepted theory by 1969

Texas A&M UniversityOceanographyOCNG 251

CRUST: granite and basaltic

MANTLE: silicate

CORE: iron, nickel and sulfur

LITHOSPHERE: rigid (100 km)

ASTHENOSPHERE: plastic (700 km)

MESOSPHERE: rigid (2900 km)

OUTER CORE: liquid (5,100 km)

INNER CORE: rigid (6370 km)

CRUST:

granite (2.7 g/cm3)

basaltic (2.9 g/cm3)

MANTLE:

silicate (4.5 g/cm3)

CORE:

liquid (11.8 g/cm3)

solid (16.0 g/cm3)

Average Earth: (5.5 g/cm3)

Texas A&M UniversityOceanographyOCNG 251

Breakup of Pangea