42 terms


Detrital Sedimentary rocks
rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering.
Chemical Sedimentary Rocks
sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means.
The main minerals of detrital rocks?
Clay, Quarts,Micas,Feldspars
Common Chemical Sedimentary rocks?
Limestone, Calcite
main rock forming mineral.
from the greek work "broken", consist of discrete fragments and particles that are cemented and compacted together. Although cement is present in the spaces between particles, the openings are rarely filled.
crystalline texture in which the minerals form a pattern of interlocking crystals.
are skeletal fragments of marine or land organisms that are found in sedimentary rocks laid down in a marine environment—especially limestone varieties
Agents of Metamorphism
Heat, Pressure, Active Fluids
gives the rock layered appearance, a term for a linear arrangement of textural features often exhibited by metamorphic rocks.
metamorphic rocks that do not exhibit foliation.
"fish Scale" appearance (mica minerals are the most common to form this texture)
principle of superposition
each bed of rock is older than the one above and younger than the one below layers of a cake
Principle of original horizontality
means that layers of sediment are generally deposited in a horizontal position.
Principle of cross cutting relationships
when a fault cuts rhrough other rocks, or when magma intrudes and crystallizes, a rock or fault is younger than any rock through which it cuts.
are fragments of one rock unit that have ben enclosed within another.
angular unconformity
consist of tilted or folded sedimentary rocks that are overlain by younger, more flat lying strata
a type of unconformity in which the beds above and below are parallel.
an unconformity in which older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata.
Principle of fossil succession
fossil organisms succeed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content.
Principle of Lateral Continuity
layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous.
the largest time unit on the gologic time scale, next in order of magnitude above era
major division on the geologic time scale? they are divided into shorter units called periods.
a basic unit of the geologic time scale that is a subdivision of era
Structural Geology
a branch of geology which study all types of crustal deformations
compressional stress
differential stress that squeezes and shortens a rock mass
tensional stress
stress that pulls apart or elongates a rock unit
Shear Stress
the movement of one part of a rock body past another. its similar tot he slippage that occurs between individual playing cards
Brittle deformation
rocks that break into smaller pieces after elastic limit is surpassed
Ductile deformation
is a type of solid state flow that produces a change in the shape of an object without fracturing
usually arise by upfolding, or arching of sedimentary layers and are sometimes spectacularly displayed along highways
usually sink or downfolds, or troughs association with anticlines
are large, steplike folds in otherwise horizontal sedimentary strata.
circular, downwarped structure, younger rocks in the middle, older on the outside
circular, upwarped structure, older rocks in the middle, younger on the outside
Dip-Slip Faults
faults in which movement is primarily parallel to the dip (incline) of the fault
Normal Faults
created by tensional stress, crust is growing longer and getting thinner
reverse fault
created by compressive stress the crust is shorten and thicken (dip inclined at angle more than 45 degrees)
thrust faults
is a reverse fault but inclined at less than 45 degrees
Strike Slip fault
a fault in which the dominant displacement is horizontal and parallel to the trend or strike of the fault
Transform Fault
are large strike slip faults that cut through the lithosphere and accomodate motion between two large tectonic plates.
are fractures along which no appreciable displacement has occurred