Theory of Plate Tectonics and the Formation of Continents

Greek word “tekton”

meaning “carpenter/builder”

Plate Tectonics

scientific theory explaining how major landforms are created by subterranean movements

plates

massive slabs of solid rock that surround Earth's surface

lithospheric plates

rigid puzzle pieces floating over the asthenosphere

asthenosphere

hot, viscous, ductile and mobile layer of the upper mantle

Raisin Theory

post-Big-Bang cooling caused Earth to contract

Clarence Edward Dutton

proposed Isostasy (1889)

Isostasy

the gravitational ‘state of balance’ between the Earth's crust and fluid mantle beaneth it

Continental Dirft Theory

presented evidence of Pangea's existence

Alfred Wegener

German climatologist; authored ‘The Origins of Continents and Ocean’ (1915)

Pangea

“pan” and “gaia” meaning “all earth”

Permian

Pangea existed

Triassic

formation of Laurasia and Gondwanaland (north & south)

Tethys Sea

separated two supercontinents

Jurassic

further rifting; opening/formation of Atlantoc Ocean

Cretacous

present-day continents/oceans have been formed

northward moving of India

formed mountain ranges

Primary Plates

consists of 7 plates

Secondary Plates

consists of 8 small plates

major tectonic plates

15 (consists of primary and secondary plates)

continental crust

lower density; composed of granitic rocks et al.

basement rock

oldest foundation (≈ 4B y/o)

cratons

highly stable interior of continents

continental margins

edges of cratons & creates natural landforms

oceanic crust

heavier but thinner, consists of basalt and gabbro rocks

magma/volcanic eruptions

forms the two types of plates