Plate Tedctonics

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Continental Drift: An Idea Before Its Time

- Alfred Wegener

_First proposed hypothesis, 1915

_Published The Origin of Continents and Oceans

- Continental drift hypothesis

_Supercontinent called Pangaea began breaking apart about 200 million years ago

_Continents "drifted" to present positions

_Continents "broke" through the ocean crust

- Wegener's continental drift hypothesis

_Evidence used by Wegener

. Fit South America and Africa

. Fossils Match across the seas

. Rock types and structures match

. Ancient climates

The Great Debate

- Rejection of the drift hypothesis

_Main objection of Wegener's proposal was its inability to provide a mechanism

Theory of Plate Tectonics

- More encompassing than continental drift

- Associated with Earth's rigid outer shell

_Called the lithosphere

_Consists of several plates

. Plates are moving slowly

. Largest plate is the Pacific plate

. Plates are mostly beneath the ocean

Guatemala is influenced by three plates: the cocos plate, the caribbean plate and the north american plate.

The land is divided two plates: the caribbean and the north american plates

Between the North american plate and the Caribbean plate are the Motagua fault and Polochic fault

magma is liquified rock under the earth that later comes out

Plate Boundaries

- Divergent plate boundaries (constructive margins)

_Two plates move apart

_Mantle material upwells to create new seafloors

_Ocean Ridges

- Convergent plate boundaries (Destructive margins)

_Oceanic-oceanic convergence

. Two oceanic slabs converge

_Continental-continental convergence

Changing Plates and Plate Boundaries

- Breakup of Pangaea

_Formed a new ocean basin - the Atlantic