Physical Science Unit 4 Vocab

Front 1

crust

Back 1

the uppermost compositional layer of the earth; very thin and composed of two parts: granitic continental crust and the basaltic oceanic crust

Front 2

mantle

Back 2

the middle compositional layer of the earth; thick layer made up of peridotite in the upper part and higher density rocks of peridotite composition in the lower part

Front 3

peridotite

Back 3

a rock made up of mostly silicon, oxygen, and the transition metals iron, and magnesium that is denser than the basalt and granite that make up the earth's crust

Front 4

stony chondrites

Back 4

meteorites thought to represent material from small planetary bodies that had differentiated into layers and then were broken up

Front 5

stony achondrites

Back 5

meteorites thought to represent material from small planetary bodies that had differentiated into layers and then were broken up

Front 6

iron meteorites

Back 6

meteorites thought to represent the type of material found in the earth's core

Front 7

core

Back 7

the deepest or central compositional layer of earth; it is composed mostly of iron

Front 8

lithosphere

Back 8

the rigid outer shell of the earth, which consists of the crust and the outermost part of the mantle that is too cool to be partially molten

Front 9

elastic rebound

Back 9

the point at which stress in the Earth's lithosphere is strained to a point where it can bend no further and the lighosphere ruptures and rebounds somewhat like a rubber band that has just been pulled apart

Front 10

fault

Back 10

a break in the earth's lithosphere along which earthquakes have occurred

Front 11

tectonic plates

Back 11

the brittle, rigid but thin outer part of the Earth is divided into sections called tectonic plates

Front 12

seismic waves

Back 12

waves produced by earthquakes

Front 13

P-waves

Back 13

compressional waves produced by an earthquake; they travel the fastest in earth and so are the first to arrive at the seismic wave detectors

Front 14

S-waves

Back 14

shear waves produced by an earthquake; they are slower than P-waves and so arrive later at seismic wave detectors

Front 15

focus

Back 15

the place inside the earth where an earthquake originates

Front 16

epicenter

Back 16

the point on earth's surface directly above the focus of an earthquake

Front 17

seismograph or seisometer

Back 17

a seismic wave detector

Front 18

seismic discontinuity

Back 18

a place where the velocities of seismic waves change abruptly

Front 19

moho

Back 19

the seismic discontinuity at the base of Earth's crust

Front 20

shadow zone

Back 20

a region of Earth were seismic waves cannot be detected by seisometers

Front 21

outer core

Back 21

the upper part of the core that is made of liquid iron

Front 22

inner core

Back 22

the lower part of the core that is made of solid iron

Front 23

curie temperature

Back 23

the temperature at which a material loses its magnetism

Front 24

silicates

Back 24

minerals that contain silicon and oxygen bonded together

Front 25

dense oxides

Back 25

minerals that form deep in Earth's mantel due to the enormous pressures

Front 26

lithosphere

Back 26

the uppermost mechanical layer of the earth; brittle and is the only layer in which earthquakes can occur

Front 27

low-velocity zone

Back 27

a region of the upper mantle where seismic waves travel slower than expected

Front 28

asthenosphere

Back 28

a soft, plastic, partially-molten mechanical layer in earth located below the lithosphere

Front 29

mesosphere

Back 29

the mechanical layer between the asthenosphere and the outer core; solid, but still plastic and able to flow