terms Flashcards
(45 cards)
strata/bed
The layers of the sedimentary rock
bedding planes
separates strata
cross-bedding
occurs when the layers in the sedimentary rock are inclined
graded beds
where the sediments in a strata gradually change from coarse at the bottom to fine at the top
ripple marks
small waves that are lithified in the sed rocks
mud cracks
indicate sediments form in an alternatively wet and dry environment.
fossil
remains of prehistoric life
carbon cycle
movement of carbon throughout earth’s spheres
metamorphism
means “to change form”
metamorphic grade
degree to which the parent rock changes during metamorphism
agents of metamorphism
heat, pressure, differential stress, chemically active fluids
recrystallization
process of forming new, stable minerals larger than the original.
geothermal gradient
increase in temp with depth
contact metamorphism
rising mantle plumes
confining pressure
forces applied equally in all directions+become compact with greater densities
compressional stress
shortened in 1 direction, elongated in the other direction
differential stress
forces are unequal in different directions
foliation
any planar arrangement of mineral grains or structural features within a rock
schistocity
exhibit a planar or layered structure
gneissic texture
segregation of mineral into light and dark bands
porphyroblastic texture
usually large grains surrounded by fine-grained matrix of other minerals
index minerals
good indicators of metamorphic grades, and thus zones of metamorphism
superposition
In an undeformed sequence of sed rocks, each bed is older than the one above and younger than the one below
original horizontality
layers of sediment are generally deposited in a horizontal position
