GEOL 113 Exam 3

Uniformitarianism

Geologic processes that occur today (e.g., volcanoes, rivers/streams, earthquakes) that have occurred in the past

Principle of original horizontality

All rock layers are originally laid down (deposited) horizontally and can later be deformed.

principle of superposition

When two or more waves overlap in space, the resultant disturbance is equal to the algebraic sum of the individual disturbances.

Unconformity

A time gap in the rock record

angular unconformity

separates rocks at a non-horizontal angle, represents a huge gap in time.

Cross-cutting relationships

Any geological feature that cuts across, or disrupts another feature must be younger than the feature that is disrupted.

fossil

The remains or traces of prehistoric life preserved in rock

faunal succession

Different organisms appear in a predictable order in sedimentary rock layers, and that this order can be used to determine the relative ages of the rocks

Biostratigraphy

Compares fossil assemblages found in different rock layers. Fossils of certain organisms are known to have lived during specific time periods, and if a rock layer contains these fossils, it can be inferred that the rock layer is of a similar age to the time period when those organisms were alive.

relative dating

based upon the order of formation, older vs. younger relationships

absolute dating

the actual number of years since an event, age is assigned a number

radioactivity

The process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive.

parent isotope

An unstable radioactive isotope

daughter isotope

the product isotope that results from the decay of a parent.

Half-life

The time required for one-half of the radioactive (parent) isotopes in a sample to decay to radiogenic (daughter) isotopes

Radioactive dating

Measures how much of each type of radioactive element is present in a material to calculate the age of a rock.

70%

What percentage of the earth is covered by the ocean?

Pacific Ocean

What is the worlds largest ocean?

1/3

What fraction of the earth does the pacific ocean cover?

Mid-ocean ridge

Divergent plate boundary, sea floor spreading. Long chain of mountains on the ocean floor

abyssal hill

A small hill that rises from the floor of an abyssal plain, there are the most abundant geomorphic structures on earth.

abyssal plain

A vast, flat, area on the ocean floor. The largest and most extensive features on the ocean floor and cover about 40% of the earth’s surface.

Deep ocean trench

Convergent plate boundary, subduction of the lithosphere. Deep narrow valleys along the edges of the ocean floor.

sea mount

Underwater volcanic mountain

guyot

Isolated underwater volcanic mountain with a flat top- more than 200cm below surface of sea

continental shelf

A gently sloping, shallow area that extends outward from the edge of each continent

continental slope

A steep incline of the ocean floor leading down from the edge of the continental shelf

Continental rise

A major depositional regime in oceans made up of thick sequences of material that accumulate between the continental slope and abyssal plane.

submarine canyons

steep-sided valleys cut into the continental slope

turbidity currents

Sediment laden water currents that flow down the continental slope

turbidite deposits

material deposited by turbidity currents, looks like a fan

Terrigenous sediment

Originates from continental sources transported by rivers, wind, ocean currents, and glaciers.

pelagic sediments

The deposits of the open ocean that accumulate on the ocean floor protected from terrestrial influence

Salinity

The measure of the amount of dissolved material in water

35 ppt

What is the average salinity

96\.5% water, 3.5% dissolved substances (mostly salts)

What is the composition of seawater

deep-sea currents

A mass movement of water that flows through the deep ocean

Differences in density between masses of ocean water

What is the primary driving force of deep sea currents

upwelling

Movement of deeper ocean water toward the ocean surface, can also occur at diverging ocean surface currents

Brings up cold nutrient rich water near earths life abundant surface

biological significance of upwelling

Global wind patterns

primary driving force of ocean surface currents

Coriolis effect

the effect of earth’s rotation on the direction of winds and currents to be deflected

North deflects to the right and south deflects to the left

What direction does the Coriolis effect deflect surface currents

gyre

closed loops of ocean surface currents

They transport warm waters into cooler areas and vice versa, acting to moderate global climate

Importance of ocean surface currents

wave height

vertical distance between crest and trough

wavelength

distance traveled during one cycle of a wave

wave period

the time it takes to complete one wave cycle

wave height, period, and length

Wave features affected by wind speed

wave height, period, and length

wave features affected by length of time wind blows

wave height, period, and length

wave features affected by fetch

circular motion

How do indvidual water particles move as a wave passes by in open ocean

Break at the shoreline

When the depth is less than half the wave height and the wave body can no longer support the height of the wave and falls under gravity

longshore current

when wave movement is parallel to the coastline

longshore drift

the movement of sediment carried by a longshore current

tides

locally higher/lower levels of the ocean surface

what causes tides?

gravitational attraction that moon exerts on earth and effect of centrifugal forces of earth/moon system

neap tides

The sun and moon gravitational pulls are fighting with each other (1/3 and 3/4 moons)

spring tides

The gravity of the sun and moon pull in the same direction (whole and new moons)

reef

coral reefs are precipitates of calcium carbonate

sediment-rich coastline

characterized by a high concentration of sedimentary deposits. Depositional

sediment-poor coastline

Characterized by a low concentration of sediment, erosional

spit

beach extended from the mainland across bay due to longshore dirft

baymouth bar

spit that extends all the way across a bay

barrier island

longshore islands of sediments that trend parallel to mainland shore

wave cut platform

nearly horizontal surface extending from beneath a wave-cut cliff to the ocean

sea arch

an arch formed in a headland by wave erosion

sea stack

the remaining structures when a sea arch collapses

estuary

a semi-enclosed coastal body of water that has a free connection with the ocean but contains brackish water

Estuary

What is the delaware bay an example of?

sediment-rich coastline

What type of shoreline is delaware an example of?

radiation

A form of heat transfer in which energy is emitted by one body, travels trough a medium or space, ultimately to be absorbed by another body

electromagnetic wave

electric and magnetic components which move as waves outward in all direction from the energy source

electromagnetic waves traveling at the speed of light

How is heat from the sun transferred?

conversion of hydrogen to helium through nuclear fission

what is the suns source of heat?

400-700 nm

wavelengths of visible light

The shirt is reflecting red lgiht and absorbing all other colors. The reflected light is the color we see the shirt as

why does a red shirt look red?

rotation

The action of spinning around an axis

Revolution

the action of spinning around another object

perihelion

a date when the earth is closest to the sun (january 3rd)

aphelion

a date when the earth is furthest from the sun (july 4)

The title of the earth’s axis causing different parts of earth’s surface to receive higher/ lower intensities of solar radiation

what causes seasons?

solstice

The time at which the sun reaches its maximum or minimum declination marked by the longest and shortest days.

equinox

The time at which the sun crosses the celestial equator when day and night are approximately equal length

tropic of cancer

23\.5 degrees north of the equator

tropic of capricorn

23\.5 degrees south of the equator

circle of illumination

the half of the earth that is illuminated by the sun

due to earth’s tilt of the rotational axis with respect to the sun

why are hours of daylight shorter in the winter and longer in the summer

oxygen, hydrogen, carbon dioxide, and argon

the most abundant gases in the atmosphere

oxygen, ozone, carbon dioxide, water vapor, and dust

the most significant components of the atmosphere

Present day atmosphere contains lots of oxygen, When the earth was first formed there was no oxygen. Present day atmosphere contains low levels of carbon dioxide. Early earth’s atmosphere has much higher levels of carbon diozide.

What are the differences between present day atmosphere and the atmosphere when the earth was first formed

Atmospheric pressure

The force exerted on a surface by the air above it as gravity pulls it to earth.

The amount of air rapidly decreases

What happens to atmospheric pressure as the heigh above the earth’s surface increases?

Troposphere

The lower most layer, temperatures decrease to -60 degrees C

Stratosphere

Second lower most layer, temperatures increase from -60 - 0 C

Mesosphere

Third lower most layer, temperatures decrease from 0 - -90 C

Thermosphere

Top layer of the atmosphere, temperatures slightly increase to -90 to -60 to -30 C

Presence of ozone absorbing ultraviolet radiation from sun

Why does temperature increase in the stratosphere

evaporation

change of state from liquid to gas- absorbs heat