EEPS Terms

lithosphere

lithosphere

the crust and the upper part of the mantle. rigid

asthenosphere

the rest of the upper mantle. plastic

SiO4 4-

silicates

O2-

oxides

CO3 2-

carbonates

sulfur, many possible anions

sulfides

SO4 2-

sulfates

Cl-, F-, Br-

halides

no anion (only one element)

native elements

phaneritic

large, visible crystals from cooling underground (plutonic)

porphyritic

large crystals held together by small+cohesive crystals from cooling partially above ground (volcanic)

aphanitic

can’t see grains with naked eye

mafic

dark color minerals, likely from earlier cooling or oceanic crust.

augute, ca-rich plagioclase

intermediate

mixed light and dark minerals, from collision of continental and oceanic crust

augite, Ca-Na plagioclase, amphibole

felsic/sialic

light colored minerals, likely from later cooling or continental crust

biotite, Na-rich plagioclase, orthoclase, muscovite, quartz

gabbro

mafic, phaneritic

basalt

mafic, porphyritic

scoria

mafic, aphanitic

diorite

intermediate, phaneritic

andesite

intermediate, porphyritic

granite

felsic, phaneritic

rhyolite

felsic, porphyritic

pumice

felsic, aphanitic

clastic

made of loose particles accumulated in shorelines, basins, rivers, deserts, etc.

chemical

made from minerals that precipitated from ions dissolved in water

regional/burial metamorphism

from high pressures in mountain building zones. foliated

contact metamorphism

from high temperatures close to igneous intrusions. nonfoliated

principle of uniformitarianism

the physical processes we observe today also operated in the past at roughly the same rate

original horizontality

sediments settle out of fluid because of gravity onto relatively flat surfaces —> sedimentary strata are originally horizontal

superposition

in the sequence of strata, each layer must be younger than the one below it

lateral continuity

sediments generally accumulate in large, continuous sheets

principle of cross-cutting relationships

if one geologic feature cuts across another, the feature that has been cut must be older

principle of inclusions

inclusions (rock fragments incorporated into other rocks) must be older than the rock they are included in

principle of baked contacts

when a magma body intrudes into cool rock, it bakes (metamorphoses) the surrounding rock. The baked rocks are older than the intrusion

principle of faunal succession

fossil assemblages succeed each other vertically in a specific, reliable order

unconformities

gaps in the rock record indicating a period of erosion or nondeposition

angular unconformity

the strata above the unconformity are angled differently than the strata below

nonconformity

sedimentary strata overlie basement rock (igneous or metamorphic)

disconformity

the strata uplifted so no new sediment deposited or some strata eroded before new deposition

joints

cool temperature. Planar discontinuities form under tension (pulling apart)

fractures

cool temperature. Planar discontinuities across which rock bodies have been displaced

faults

cool temperature. Fractures with significant displacement.

folds

hot or cold temp. Rock layers fold over

foliations

hot temperature

strike

the line of intersection between an inclined plane and a horizontal plane. Reported as a compass direction

dip

direction and magnitude of tilt measured with respect to horizontal plane

right hand rule

place your right hand with your fingers facing down dip and your thumb perpendicular to your fingers. Record strike along the direction your thumb points

dip-slip fault

moves in the dip direction of the fault surface (up or down)

normal fault

the hanging wall moves down with respect to the foot wall

reverse fault

hanging wall moves up with respect to the foot wall

strike-slip fault

moves in the strike direction of the fault surface (right or left)

axial plane

imaginary plane that divides a fold into mirror pieces

hinge line

the imaginary line that the rock folds along

anticline

the rock folds downward, warps upward (forming upside down U), younging direction is outwards

syncline

the rock folds upward, warps downward (forming U), younging direction is inwards

drainage basin

land area from which a stream system collects water

drainage divides

ridges or areas of high topography that separate drainage basins

discharge (Q)

the volume of water passing a reference point in a given time. Q=Av where A=cross sectional area and v=average velocity

thalweg

the deepest and fastest moving part of the channel. Follows the outer curves in curved streams

dissolved load

the ions dissolved in the water

suspended load

smallest grain sizes (silts+clays) which float along without touching the bottom

bed load

larger grains (salt and gravel) which move by bouncing and rolling along the bottom. They settle out if the velocity is not high enough

lee side

downstream

stoss side

upstream

hill

isolated high area, peak

valley

line of low elevation, frequently has a stream

ridge

line of high elevation, has hills (peaks) along it

saddle

low lying area between two peaks

depression

“monster mouth”. same pattern as peak, but with little lines pointing inwards from the contour lines

leading edge shoreline

tectonically active. Typically rugged and irregular; possibly slow seaward show migration. Primary hazard is mass wasting

trailing edge shoreline

little/no tectonic activity. Relatively straight; often rapid landward shoreline migration. Primary hazards are flooding and tropical storms.

barrier islands

elongated sedimentary deposits separated from the mainland by by ocean/lagoon/tidal flat. Only found on trailing edge shorelines

seawall

barrier parallel to shoreline to absorb wave energy and prevent erosion

groins

barriers perpendicular to the shoreline to prevent longshore drift

jetties

a pair of structures perpendicular to the shoreline to keep a channel open

breakwaters

structures parallel to the shoreline offshore to prevent waves from breaking on certain parts of the beach

geotubes

fibrous tubes filled with sand that are placed backbeach and covered with sand to mimic dunes. Meant to prevent the beach from moving towards the land.

growth faulting

rapid sediment deposit over a weak layer —> pressure causes the weak layer to squish and move —> collapse of overlying sediment —> differential pressure

salt movement/tectonics

salt acts like a liquid that floats up through other sediments., creates salt domes Typically forms diapirs (inverted teardrop shaps)

groundwater mining/subsidence

lowering the water table causes the land to shift

porosity

volume of voids / total volume

permeability

how connected the pore spaces are

oil traps

structures that hold oil. Anticlines adjacent to faults/salt domes or salt domes capped by limestone or anhydrite

aquifer

materials with low to high porosity and permeability. Hold water well

aquitard

material with low porosity and permeability. Does not hold water well

unconfined aquifer

exposed to changes in the atmosphere (temperature and pressure). They will fill up to the water table unless perched (sitting on top of an impermeable layer); are higher in the wet season

confined aquifer

capped, causing high pressure.

hydraulic head

how much the water in a confined aquifer would rise from the pressure

craton

a stable block/piece of crust that stays around for a long time

platforms

phanerozoic sedimentary rocks covering precambrian basement rock

shield

craton material exposed at Earth’s surface. Usually very low relief

accreted terrane

volcanic islands/microcontinents that collide with and are added onto continental margins during orogenesis

Grenville Orogeny

1 Ga, last of collisions to form Rodinia. Incorporated into Appalachians during Pange (~251 mya)

Taconic Orogeny

Middle Ordovician, 1st of Appalachian orogenies. Volcanic island arc collided with the east coast

Acadian Orogeny

Silurian-Devonian, 2nd of Appalachian orogenies. Microcontinent Avalonia collided with the east coast

Alleghanian Orogeny

Permian, 3rd of Appalachian orogenies. Africa collided with the east coast during the formation of Pangea

Slave Lake

oldest rocks in North America

Lake Superior

largest craton in North America

Antler Orogeny

Late Devonian. Formation of volcanic island arc collided with the west coast (several accreted terranes in Mesozoic)