plate tectonics

-made by Alfred Wegener


-continents drifted apart

-fit of s. america to africa

-fossil evidence

-rock structures

-ancient climates

-S. america to africa

-edges on the continents fit perfectly prior to all the erosion

Mesosaurus limited to S. Africa and E. America

• -similar rock type in S. America and Africa
• igneous rocks similar

-mountain ranges are similar rock types

• -pangea was centered over south pole
• accounts for ext. glaciation in S. Hemisphere

• one great continent composed of all continents got together at one point
• they eventually broke up

-Transoceanic land bridges: how animals got from Africa to S. America

Siberia and Alaska

• -mid oceanic ridges show that the older layers go into the mantle.
• new land comes out

-measured magnetism in lava rocks

-pattern of alternating striped of HI and LOW magnetism

• -SFS carries old magma away from the ridge
• new magma magnetized

normal polarity

reversed polarity

-destructive margins

-come together, one beneath the other

-large earthquakes by subduction zone

-mtn ranges form from collisions

-contructive margins

-plates move apart, new seafloor created

• -continental rifting
• spreads landmasses

-conservative margins

-plates grind past one another

-no subduction

-no new crust formed

-earthquakes are prone to happen near faults

-provides transportation for the new crust formed at the ridges to the subduction zone

-convective mantle flow drives plate movement

-plate subduction drives downward movement of convection

-unequal distribution inside of Earth