Terms

Question 1

force applied to a rock per unit area

Answer 1

stress

Question 2

change in a rock’s composition by fluid transport of chemical substances into or out of it

Answer 2

metasomatism

Question 3

the most widespread type of metamorphism that takes place where both high temperatures and high pressures are imposed over large parts of the crust

Answer 3

regional metamorphism

Question 4

where the heat from an igneous intrusion metamorphoses the rock immediately surrounding it

Answer 4

contact metamorphism

Question 5

where hot basaltic lava at a seafloor spreading center heats infiltrating seawater

Answer 5

seafloor metamorphism

Question 6

low grade metamorphism that is caused by the progressive increase in pressure exerted by the growing layers of overlying sidemen’s and sedimentary rocks and by the increase in heat associated with increased depth of burial

Answer 6

burial metamorphism

Question 7

rocks formed by pressure 8 to 12 kbar

Answer 7

high pressure metamorphism

Question 8

rocks formed by pressures greater than 28 kbar

Answer 8

ultra-high pressure metamorphism

Question 9

unusual metamorphic rocks once located at the base of the crust that are now found at the surface

Answer 9

eclogites

Question 10

occurs when a meteorite collides with earth

Answer 10

shock metamorphism

Question 11

a set of flat or wavy parallel cleavage planes produced by deformation of igneous and sedimentary rocks under directed pressure

Answer 11

foliation

Question 12

rocks classified according to metamorphic grade, grain size, type of foliation, and banding

Answer 12

foliated rocks

Question 13

the lowest grade of foliated rocks

Answer 13

slates

Question 14

rocks of a slightly higher grade than slate

Answer 14

phyllite

Question 15

the parallel arrangement of platy minerals that produces a coarse, wavy foliation known as schistosity; intermediate grade

Answer 15

schist

Question 16

light colored rocks with coarse bands of light and dark minerals throughout the rock

Answer 16

gneiss

Question 17

rocks that melt slightly before solidifying again creating a badly deformed and contorted rock that is penetrated by veins, small pods, and lenses of melted rock

Answer 17

migmatite

Question 18

non foliated metamorphic rocks composed mainly of crystals that grow in equidimensional shapes such as cubes and spheres

Answer 18

granoblastic rocks

Question 19

a high temperature contact metamorphic rock of uniform grain size that has undergone little or no deformation

Answer 19

hornfels

Question 20

large crystals found in rocks formed both by contact and by regional metamorphism

Answer 20

porphyroblasts

Question 21

the makeup of lowest grade rocks in regional metamorphism of a basalt

Answer 21

zeolite

Question 22

a higher grade of metamorphosed mafic volcanic rocks

Answer 22

greenschists

Question 23

mafic volcanic rocks where the pressure is high and the temperature is moderate

Answer 23

blueschist

Question 24

groupings of rocks of various mineral compositions formed under particular conditions of temperature and pressure from different parent rocks

Answer 24

metamorphic facies

Question 25

transported back to earth's surface

Answer 25

exhumed

Question 26

the distinctive history of changing temperature and pressure that is reflected in the texture and mineralogy of metamorphic rocks

Answer 26

P-T path (pressure-temperature path)

Question 27

the remnant of such a boundary left behind in the geologic record

Answer 27

suture

Question 28

stretch and pull rock formations apart and dominate at divergent boundaries

Answer 28

tensional forces

Question 29

squeeze and shorten rock formations and dominate at convergent boundaries

Answer 29

compressive forces

Question 30

shear two parts of a rock formation in opposite directions and dominate at transform boundaries

Answer 30

shearing forces

Question 31

groups of rock layers that can be identified throughout a region by their physical properties

Answer 31

formations

Question 32

the compass direction of a rock layer where it intersects with a horizontal surface

Answer 32

strike

Question 33

the angle at which the rock layer inclines from the horizontal

Answer 33

dip

Question 34

two dimensional representations of the rock formations exposed at earth's surface

Answer 34

geologic maps

Question 35

diagrams showing the features that would be visible if vertical slices were made through part of the crust

Answer 35

geologic cross sections

Question 36

pliable

Answer 36

ductile

Question 37

a fracture that displaces the rock on either side of it

Answer 37

fault

Question 38

a fault on which there has been relative movement of blocks of rock up or down the dip of the fault plane

Answer 38

dip-slip fault

Question 39

a fault on which the movement of blocks has been horizontal, parallel to the strike of the fault plane

Answer 39

strike-slip fault

Question 40

the block of rock above a dipping fault plane

Answer 40

hanging wall

Question 41

block of rock below a dipping fault plane

Answer 41

foot wall

Question 42

a dip-slip fault if the hanging wall moves downward relative to the foot wall, extending the structure horizontally

Answer 42

normal fault

Question 43

a low angled reverse fault so that the movement is more horizontal than vertical

Answer 43

thrust fault

Question 44

faults that are both strike-slip and dip-slip

Answer 44

oblique slip faults

Question 45

occur when an originally planar structure is bent into a curved structure

Answer 45

fold

Question 46

folds in which layered rocks are bent upward into arches

Answer 46

anticlines

Question 47

folds in which rocks are bent downward into troughs

Answer 47

synclines

Question 48

have limbs that dip symmetrically from the axial plane

Answer 48

symmetrical folds

Question 49

have one limb that dips more steeply than the other

Answer 49

asymmetrical folds

Question 50

have limbs that dip in the same direction, but one limb has been tilted beyond the vertical

Answer 50

overturned folds

Question 51

a bowl-shaped depression of rock layers in which the beds dip toward a central point

Answer 51

basin

Question 52

a broad circular or oval upward bulge of rock layers

Answer 52

dome

Question 53

a crack in a rock formation along which there has been no appreciable movement

Answer 53

joint