Chapter 4 Note Cards

Front 1

continental drift

Back 1

in 1912, a German scientist, Alfred Wegener, proposed a hypothosis called contietal drift, which stated that the continents had moved.

Front 2

pangaea

Back 2

wegner hypothosized that the continents once fored part of a single landmass, which he named Pangaea ( pan - JEE - un), meaning "all land."

Front 3

panthalassa

Back 3

Surrounding Pangaea was a huge ocean, Panthalassa, meaning "all seas."

Front 4

Mid-Atlantic Ridge

Back 4

In 1947, a grou of scientists set out to map the Mid-Atlantic Ridge, an undersea mountain range with a steep, narrow valley running down its center.

Front 5

mid-ocean ridges

Back 5

the Mid-Atlantic Ridge is one part of an entire system of mid-ocean ridges 65, 000 km long that wind their way around the earth

Front 6

plate tectonics

Back 6

by the 1960's, accumulated evidence supporting the hypothesis of continental drift and seaflooor spreading led to the formulation of a more far-reaching theory. this theory is called plate tectonics.

Front 7

ocean crust

Back 7

material that makes up the ocean floor.

Front 8

continental crust

Back 8

material that makes up landmass.

Front 9

lithosphere

Back 9

the ocean an continental crust and the rigid upper mantle make up the lithosphere.(this forms the ouer shell of the earth)

Front 10

asthenosphere

Back 10

beneath the lithosphere lies the asthenosphere, a layer of plastic rck, that is, solid rock that slowly flows (like putty) when under pressure.

Front 11

divergent boundary

Back 11

the geologic acivity that occors along palte boundaries differs according to the way plates movein relation to each other. for example, two plates moving away from each other form a dvergent boundary.

Front 12

rift valley

Back 12

in the center of a mid-ocean ridge is a narrow valley formed as the plates separate. this formation is called a rift valley.

Front 13

convergent boundary

Back 13

as seafloor spreading pulls plates apart at one boundary, those paltes push into neighboring plates at other boudaries, the direction collision of one plate with another makes another type of plate boundary --- a convergent boundary.

Front 14

subuction zone

Back 14

scientist refer to the reagion along a plate boundary where one plate moves under another plate as a subduction zone.

Front 15

ocean trench

Back 15

a deep ocean trench generally forms along a subduction zone