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Scientist who came up with the theory of Continental Drift.No one believed at first, because he couldn't explain how the continents moved.
The theory that states that all Earth's continents were once a single landmass called Pangaea.
The theory that new ocean crust is formed at ocean ridges and destroyed at deep-sea trenches.
Thoery of Plate Tectonics
The theory that says Earth's crust and rigid upper mantle are broken into enormous slabs called plates.
Forms from crust being sub-ducted, pushed down, into the Earth's mantle. This magma type has an intermediate viscosity.
Forms from molten material rising and mixing with the crust above it. This magma type has a high viscosity
These produce mountains with a broad, gently sloping side and a nearly circular base.
Gondwanaland or Gondwana
Large continent in the southern hemisphere. Included the land now found in South America, Africa, Antarctica, India, & Australia
Early Evidence for Plate Tectonics
Jigsaw-like fit of Africa and South America (early mapmakers), matching rock formations on opposite sides of the Atlantic Ocean, same fossils on multiple continents, fossils indicating had different climate in past
Fern that grew in temperate climates, similar to our climate. Yet, fossils of the fern have been found in cold Antarctica and equatorial India.
Past Climate Based on Coal
Coal, made from swamp plants, has been found in Antarctica & indicates Antarctica was warmer at one time. Was it closer to equator?
Study of Earth's magnetic field, based on magnetic iron of basalt on the ocean floor. The iron lines up and "points" in the direction of the Earth's magnetic field when the magma cooled and formed rock.
Change in Earth's magnetic field. The iron in the basalt on the ocean floor indicate the Earth's magnetic field has reversed several times.
Opposite sides of an ocean ridge have mirror-image patterns of magnetic reversals.
Line on a map that connects points of equal age that were formed at the same time. Isochron maps have been used to map the age of the ocean floor - Figure 17-11 p.453
Convection (As it relates to plate tectonics)
Transfer of energy by the flow if a heated material. Convection currents in the asthenosphere (soft, plastic-like part of mantle) are thought to cause plate movement. Convection cycle rises at the mid-ocean ridges of divergent boundaries and sinks at the deep-sea trenches of convergent bondaries.
Folded (Very High) Mountains
Extremely high mountains formed when 2 continental plates converge (collide). Because the continental plates have similar density there is no subduction and plates are crumpled & forced up instead.
Formed above an oceanic-oceanic convergent boundary when volcanoes become tall enough to break the surface of the water. Examples: Aleutian Islands, Japan, Phillipines
Deep Sea Trench
Formed at convergent boundaries when subduction occurs and the more dense oceanic plate slips under another plate. The deepest one is by the Mariana Islands.
Divergent boundary in ocean where seafloor spreading occurs as magma rises, cools, forms new rock, forcing the 2 plates apart.
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