question

Alluvial fan

answer

A gently sloping apron of sediment dropped by an ephemeral stream at the base of a mountain in arid or semi-arid regions

question

Alluvium

answer

Sorted sediment deposited by a stream

question

Annual probability

answer

The likelihood, expressed as a percentage, that an event (e.g., a flood of a given size) will happen in a given year

question

Antecedent stream

answer

A stream that cuts across an uplifted mountain range. the stream must have existed before the range uplifted and must then have been able to downcut as fast as the land was rising

question

Artificial levee

answer

A man-made retaining wall to hold back a river from flooding.

question

Bar

answer

A sheet or elongate lens or mound of alluvium

question

Base level

answer

The lowest elevation a stream channel's floor can reach at a given locality

question

Bed load

answer

Large particles (such as sand, pebbles or cobbles) that bounce and roll along the stream floor.

question

Braided stream

answer

A sediment-choked stream consisting of entwined subchannels

question

Capacity

answer

The total volume of sediment that a stream can carry

question

Channel

answer

A trough dug into the ground surface by flowing water

question

Competence

answer

The ability of flowing water to carry sediment, as represented by the largest clast size that the stream can transport

question

Delta

answer

A wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out

question

Discharge

answer

The volume of water in a conduit or channel passing a point in one second

question

Distributary

answer

The fan of small streams formed where a river spreads out over its delta

question

Downcutting

answer

The process in which water flowing through a channel cuts into the substrate and deepens the channel relative to its surroundings

question

Drainage divide

answer

A highland or ridge that separates one watershed from another

question

Drainage network

answer

An array of interconnecting streams that together drain an area. May be dendritic, radial, rectangular, trellis or parallel

question

Drainage reversal

answer

When the drainage system reverses due to tectonic processes

question

Ephemeral stream

answer

A stream whose bed lies above the water table, so that the stream flows only when the rate at which water enters the stream from rainfall or meltwater exceeds the rate at which water infiltrates the ground below

question

Flash flood

answer

A flood that occurs during unusually intense rainfall or as the result of a dam collapse, during which the floodwaters rise very fast

question

Flood

answer

An event during which the volume of water in a stream becomes so great that it covers areas outside the stream's normal channel

question

Flood-hazard map

answer

Highlight flood risk zones, FEMA

question

Floodplain

answer

The flat land on either side of a stream that becomes covered with water during a flood

question

Floodway

answer

Special channels built to divert flood waters, clear areas on floodplains designed to absorb flooding

question

Fluvial deposit

answer

Sediment deposited in a stream channel, along a stream bank or on a floodplain aka Alluvium

question

Headward erosion

answer

The process by which a stream channel lengthens up its slope as the flow of water increases

question

Longitudinal profile

answer

A cross-sectional image showing the variation in elevation along the length of a river

question

Meander

answer

A snake-like curve along a stream's course

question

Natural levee

answer

A pair of low ridges that appear on either side of a stream and develop as a result of the accumulation of sediment deposited naturally during flooding

question

Oxbow lake

answer

A cutoff meander becomes a ____ if it remains filled with water

question

Permanent stream

answer

A stream that flows year-round because its bed lies below the water table, or because more water is supplied from upstream than can infiltrate the ground

question

Point bar

answer

A crescent-shaped deposit of sediment on the inside bank of a meander, the outside bank is known as the cut bank

question

Rapids

answer

A reach of a stream in which water becomes particularly turbulent. as a consequence, waves develop on the surface of the stream, form over sudden changes in channel

question

Recurrence interval

answer

The average time between successive geologic events

question

Running water

answer

Water that flows down the surface of sloping land in response to the pull of gravity.

question

Saltation

answer

The leaping movement of sand or soil particles as they are transported in a fluid medium over an uneven surface, curved trajectory

question

Seasonal flood

answer

Floods that appear almost every year during seasons when rainfall is heavy or when winter snows start to melt

question

Sheetwash

answer

A film of water less than a few millimeters thick that covers the ground surface during heavy rains

question

Stream

answer

A ribbon of water that flows in a channel

question

Stream gradient

answer

Slope or steepness of a stream channel

question

Stream piracy

answer

The situation in which headward erosion causes one stream to intersect the course of another, previously independent stream, so that the intersected stream starts to flow down the channel of the first stream

question

Stream rejuvenation

answer

The renewed downcutting of a stream into a floodplain or peneplain, caused by a relative drop of the base level

question

Stream terrace

answer

A flat surface, underlain by alluvium, that borders a stream, these form when the stream cuts down into the alluvium that it had deposited previously

question

Superposed stream

answer

A stream whose geometry has been laid down on a rock structure and is not controlled by the structure

question

Tributary

answer

A smaller stream that flows into a larger stream

question

V-shaped valley

answer

A valley whose cross-sectional shape resembles a V. the valley probably has a river running down the point of the V

question

Waterfall

answer

A place where water drops over an escarpment, may scour a plunge pool

question

Watershed

answer

A region or area bounded peripherally by a divide and draining ultimately to a particular watercourse or body of water, aka drainage basin or catchment

question

Alpine-Himalaya chain

answer

The largest orogeny on earth

question

Ancestral Rockies

answer

The late Paleozoic uplifts of the Rocky Mountain region. they eroded away long before the present Rocky Mountains formed

question

Archaen Eon

answer

The middle Precambrian Eon, after Hadean and before Proterozoic

question

Banded Iron formation

answer

Unique, shallow marine deposits made up of alternating bands of chert and iron oxides that formed due to locally high oxygen levels produced by stromatolites.

question

Basin and Range Province

answer

A broad, Cenozoic continental rift that has affected a portion of the western United States in Nevada, Utah, and Arizona. in this province, tilted fault blocks form ranges, and alluvium-filled valleys are basins

question

Cambrian explosion

answer

See Chapter 10

question

Craton

answer

An old and stable part of the continental crust that has survived the merging & breaking.

question

Cratonic platform

answer

A province in the interior of a continent in which Phanerozoic strata bury most of the underlying Precambrian rock

question

Differentiation

answer

In the context of planet formation, the process by which a planet separates into a metallic core and a rocky mantle very early in its history

question

Ediacaran fauna

answer

Earliest generally accepted animal fossils, dating from about 575 million years ago, during the Proterozoic eon

question

Epicontinental sea

answer

A shallow sea overlying a continent during the early paleozoic era--no ice caps

question

Exotic terrain

answer

New land that has been formed somewhere else and moved to its present location

question

Gondwana

answer

Late Paleozoic continent that formed the southern portion of Pangaea, consisting of all or parts of present-day South America, Africa, Australia, India, and Antarctica

question

Great oxygenation event

answer

The time when minerals became too saturated to absorb any free oxygen in the air, so when plants continued to use photosynthesis to create oxygen it accumulated on a never before seen level.

question

Hadean eon

answer

The oldest of the Precambrian eons. the time between Earth's origin and the formation of the first rocks that have been preserved

question

Laramide orogeny

answer

The mountain-building event that lasted from about 80 Ma to 40 Ma, in western North America. in the United States, it formed the Rocky Mountains as a result of basement uplift and the warping of the younger overlying strata into large monoclines, late mesozoic

question

Laurentia

answer

A continent in the early Paleozoic Era composed of today's North America and Greenland

question

Pangea

answer

A supercontinent that assembled at the end of the Paleozoic Era, Permian Period

question

Phanerozoic Eon

answer

The most recent eon, an interval of time from 542 Ma to the present

question

Pleistocene Ice Age

answer

The period of time from about 2 Ma to 14,000 years ago, during which the Earth experienced an ice age

question

Proterozoic Eon

answer

The most recent of the Precambrian eons

question

Rodinia

answer

A supercontinent older than Pangaea that formed about 1.1 billion years ago and began to break up about 750 million years ago. Proterozoic eon

question

Shield

answer

An older, interior region of a continent

question

Snowball Earth

answer

Hypothesis that proposes that the Earth was entirely covered by ice in part of the Cryogenian period of the Proterozoic eon, and perhaps at other times in the history of Earth

question

Superplume

answer

A huge mantle plume, underlies the African continent and is breaking the continent apart

question

Cambrian explosion

answer

The remarkable diversification of life, indicated by the fossil record, that occurred at the beginning of the period of the same name

question

Closure temperature

answer

One of the problems with radiometric dating, radioactive material must reach a certain temperature before it begins to "set it's timer". Hence, no rocks date back to the Hadean eon (never reached this temp).

question

Contact

answer

The boundary surface between two rock bodies (as between two stratigraphic formations, between an igneous intrusion and adjacent rock, between two igneous rock bodies, or between rocks juxtaposed by a fault)

question

Correlation

answer

The process of defining the age relations between the strata at one locality and the strata at another locality (even across seas!)

question

Cross-cutting relations

answer

A means of determining the relative age of rock by looking at which rock or structure cuts another. the feature that has been cut is older

question

Daughter isotope

answer

The product isotopes of radioactive decay

question

Eon

answer

The largest subdivision of geologic time, breaks all time into 4 parts

question

Epoch

answer

An interval of geologic time representing the largest subdivision of a period

question

Era

answer

An interval of geologic time representing the largest subdivision of the Phanerozoic Eon (only this Eon is subdivided, and it is divided into 3)

question

Fossil assemblage

answer

A group of fossil species found in a specific sequence of sedimentary rock

question

Fossil succession

answer

The principle that the assemblage of fossil species in a given sequence of sedimentary strata differs from that found in older sequences or in younger sequences. a given species appears at a certain level and then disappears (goes extinct) at a higher level

question

Geochronology

answer

Study of the ages of geologic events

question

Geologic column

answer

An ideal sequence of rock layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest, may also be composed for a single region

question

Geologic history

answer

The sequence of geologic events that has taken place in a region.

question

Geologic map

answer

Shows the surface geology of the mapped Includes rock types, their ages, and location of faults

question

Geologic time

answer

A record of the geologic events and life forms in Earth's history, divided into 4 eons OR 4 eras, includes scale

question

Geologic time scale

answer

A scale that describes the intervals in geologic time

question

Half-life

answer

The time it takes for half of a group of a radioactive element's isotopes to decay

question

Index fossil

answer

A fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found

question

Isotope

answer

Different versions of a given element that have the same atomic number but different atomic weights, aka have more or less neutrons

question

Isotopic dating

answer

The science of dating geologic events in years by measuring the ratio of parent radioactive isotopes to daughter product isotopes

question

Marker bed

answer

An easily identified geologic layer whose age has been independently confirmed at numerous locations and whose presence can therefore be used to date archaeological and geological sediments.

question

Numerical age

answer

The age of a rock or structure as specified in years. referred to as 'absolute age' in older literature. Absolute was abandoned because in reality, this is still a guess. May be done through radiometric, carbon, or isotopic dating (all the same idea).

question

Original horizontality

answer

The principle that sediments are deposited in nearly horizontal layers (1st principle of relative dating)

question

Parent isotope

answer

A radioactive isotope that undergoes decay

question

Period

answer

An interval of geologic time representing a subdivision of a geologic era--these names were given at different times and are not all the same length and do not follow a pattern for their names.

question

Precambian

answer

The interval of geologic time (known as an era, divided into 3 eons) between Earth's formation about 4.57 Ga and the beginning of the Phanerozoic Eon 542 Ma

question

Radioactive decay

answer

The process by which a radioactive atom undergoes fission aka releases particles thereby transforming into a new element

question

Relative age

answer

The age of one geologic feature with respect to another, eg feature A is older than feature B

question

Stratigraphic column

answer

A cross-section diagram of a sequence of strata summarizing information about the sequence in a given region

question

Stratigraphic formation

answer

A recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval that can be traced over a broad region. Places two now separate landmasses as being connected at a certain time.

question

Stratigraphic group

answer

Several adjacent stratigraphic formations in a succession.

question

Superposition

answer

The principle that younger layers of sediment are deposited on older layers of sediment. Thus, in a sequence of strata, the oldest layer is at the base

question

Unconformity

answer

A boundary between two different rock sequences representing an interval of time during which new strata were not deposited and/or were eroded

question

Uniformitarianism

answer

The principle that the same physical processes observed today are responsible for the formation of ancient geologic features. put concisely, 'the present is the key to the past'. Hutton.

question

Richter scale

answer

A scale that defines earthquakes on the basis of the amplitude of the largest ground motion recorded on a seismogram

question

Sediment liquefaction

answer

The transformation of seemingly solid sediment into a liquid-like slurry, in response to ground shaking

question

Seismic belt

answer

The relatively narrow strips of crust on Earth under which most earthquakes occur

question

Burial metamorphism

answer

Metamorphism due to the increase in temperature and pressure in a rock when it has been buried to a depth of several kilometers

question

Compression

answer

A type of stress that squeezes the rock, causing it to break or fold, perpendicular

question

Contact metamorphism

answer

Metamorphism caused by heat conducted into country rock from an igneous intrusion

question

Dynamic metamorphism

answer

Metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure

question

Dynamothermal metamorphism

answer

Metamorphism that involves heat, pressure, and shearing

question

Exhumation

answer

The process (involving uplift and erosion) that returns deeply buried rocks to the surface

question

Foliation

answer

Layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock

question

Gneiss

answer

A compositionally banded metamorphic rock typically composed of alternating dark- and light-colored layers

question

Hornfels

answer

Rock that undergoes metamorphism simply because of a change in temperature, without being subjected to differential stress

question

Hydrothermal metamorphism

answer

The change that occurs in a rock due to interaction with high-temperature water solutions

question

Marble

answer

A metamorphic rock composed of calcite and transformed from a protolith of limestone

question

Metaconglomerate

answer

Conglomerate that has undergone metamorphism, but in which clasts are still recognizable. typically the clasts are stretched or flattened

question

Metamorphic aureole

answer

The region around a pluton, stretching tens to hundreds of meters out, in which heat transferred into the country rock and metamorphosed the country rock

question

Metamorphic facies

answer

A set of metamorphic mineral assemblages indicative of metamorphism under a specific range of pressures and temperatures

question

Metamorphic foliation

answer

A fabric defined by parallel surfaces or layers that develop in a rock as a result of metamorphism. schistocity and gneissic layering are examples

question

Metamorphic grade

answer

An informal designation of the degree to which a rock has undergone metamorphism. high-grade rocks have endured higher temperatures than low-grade rocks

question

Metamorphic mineral

answer

A mineral formed by solid-state transitions under metamorphic conditions

question

Metamorphic rock

answer

Rock that forms when preexisting rock changes into new rock as a result of an increase in pressure and temperature and/or shearing under elevated temperatures. This occurs without the rock first becoming a melt or a sediment.

question

Metamorphic texture

answer

The arrangement of grains (e.g. preferred orientation) formed as a result of metamorphism.

question

Metamorphic zone

answer

The region between two metamorphic isograds, typically named after an index mineral found within the region

question

Metamorphism

answer

The process by which one kind of rock transforms into a different kind of rock

question

Metasomatism

answer

The process by which a rocks overall chemical composition changes during metamorphism because of reactions with hot water that bring in or remove elements

question

Migmatite

answer

Mixed igneous and metamorphic rock; forms when metamorphic rock partially melts

question

Mylonite

answer

The resulting rock from dynamic metamorphism; has a foliation that parallels the fault.

question

Phyllite

answer

A fine-grained metamorphic rock with a foliation caused by the preferred orientation of very fine-grained mica

question

Preferred orientation

answer

The metamorphic texture that exists where platy grains lie parallel to one another and/or elongate grains align in the same direction

question

Protolith

answer

The original rock from which a metamorphic rock formed

question

Quartzite

answer

A metamorphic rock composed of quartz and transformed from a protolith of sandstone

question

Regional metamorphism

answer

Metamorphism of a broad region, usually the result of deep burial during an orogeny (building of a mountain range)

question

Schist

answer

A medium- to coarse-grained metamorphic rock that possesses schistosity, shiny micca flakes

question

Shear

answer

stress that pushes masses of rock in opposite directions, in a sideways movement

question

Shield

answer

An older, interior region of a continent

question

Shock metamorphism

answer

Solid-state changes in rock that result from the extreme pressure accompanying a meteorite impact

question

Slate

answer

Fine-grained, low-grade metamorphic rock, formed by the metamorphism of shale

question

Thermal metamorphism

answer

Metamorphism caused by heat conducted into country rock from an igneous intrusion

question

Amber

answer

Hardened (fossilized) ancient sap or resin

question

Archaea

answer

A kingdom of old bacteria, now commonly found in extreme environments like hot springs

question

Bacteria

answer

A type of tiny prokaryotic single-celled organism

question

Biomarker

answer

A measurable substance in an organism whose presence is indicative of some phenomenon such as disease, infection, or environmental exposure

question

Cambrian explosion

answer

See chapter 10

question

Cast

answer

Sediment that preserves the shape of a shell it once filled before the shell dissolved or mechanically weathered away

question

Natural selection

answer

The process by which the fittest organisms survive to pass on their characteristics to the next generation

question

Paleontologist

answer

Scientists that study fossils

question

Paleontology

answer

The study of fossils

question

Petrified wood

answer

Forms by the permineralization of wood, causing the wood to become chert

question

Phylogenetic tree

answer

A chart representing the ideas of paleontologists showing which groups of organisms radiated from which ancestors

question

Preservation potential

answer

The likelihood that an organism will be buried and eventually transformed into a fossil

question

Punctured equilibrium

answer

The hypothesis that evolution takes place in fits and starts; evolution occurs very slowly for quite a while and then, during a relatively short period, takes place very rapidly

question

Taxonomy

answer

The study and classification of the relationships between different forms of life

question

Theory of Evolution

answer

The process by which organisms change over time as a result of changes in heritable physical or behavioral traits

question

Aftershocks

answer

The series of smaller earthquakes that follow a major earthquake

question

Body wave

answer

Seismic waves that pass through the interior of the Earth

question

Compressional wave

answer

Waves in which particles of material move back and forth parallel to the direction in which the wave itself moves

question

Displacement

answer

The amount of movement or slip across a fault plane

question

Earthquake

answer

A vibration caused by the sudden breaking or frictional sliding of rock in the Earth

question

Earthquake early warning

answer

Communications network that provides an alert within microseconds after the first earthquake waves arrive at a seismograph near the epicenter, but before damaging vibrations reach population centers

question

Earthquake engineering

answer

Design of structures to withstand expected levels of earthquake shaking and liquefaction

question

Elastic-rebound theory

answer

The concept that earthquakes occur when rock elastically bends until it fractures. the fracturing generates earthquake energy and decreases the elastic energy stored in the rock

question

Epicenter

answer

The point on the surface of the Earth directly above the focus of an earthquake

question

Fault

answer

A fracture on which one body of rock slides past another

question

Fault scarp

answer

A small step on the ground surface where one side of a fault has moved vertically with respect to the other

question

Fault trace

answer

The intersection between a fault plane and the ground surface

question

Foreshock

answer

The series of smaller earthquakes that precede a major earthquake

question

Friction

answer

The force that resists sliding on a surface

question

Hypocenter (focus)

answer

The point below the Earth's surface where the energy is produced during an earthquake

question

Intensity

answer

A measure of the relative size of an earthquake (the severity of ground shaking) at a location, as determined by examining the amount of damage caused

question

Intraplate earthquake

answer

Earthquake that occurs away from plate boundaries

question

Magnitude

answer

Any numerical representation of the size of an earthquake as determined by measuring the amplitude of ground motion

question

Modified Meracalli Intensity scale

answer

An earthquake characterization scale based on the amount of damage that the earthquake causes

question

Moment magnitude scale

answer

A numerical representation of the size of an earthquake that takes into account the area of the fault that slipped, the amount of slip, and the strength of the rock that broke

question

Recurrence interval

answer

The average time between successive geologic events

question

Richter scale

answer

A scale that defines earthquakes on the basis of the amplitude of the largest ground motion recorded on a seismogram

question

Sediment liquefaction

answer

The transformation of seemingly solid sediment into a liquid-like slurry, in response to ground shaking

question

Seismic belt

answer

The relatively narrow strips of crust on Earth under which most earthquakes occur

question

Seismicity

answer

Earthquake activity

question

Seismic retrofitting

answer

Strengthening of an already existing structure so it can withstand earthquake vibrations

question

Seismic wave

answer

Waves of energy emitted at the focus of an earthquake

question

Seismogram

answer

The record of an earthquake produced by a seismograph

question

Seismometer

answer

Instrument used to measure horizontal or vertical motion during an earthquake.

question

Shear wave

answer

Seismic waves in which particles of material move back and forth perpendicular to the direction in which the wave itself moves

question

Stick-lip behavior

answer

Stop-start movement along a fault plane caused by friction, which prevents movement until stress builds up sufficiently

question

Stress

answer

Push, pull or shear that a material feels when subjected to a force

question

Surface wave

answer

Seismic waves that travel along the Earth's surface. L and R waves.

question

Travel-time curve

answer

A graph that plots the time since an earthquake began on the vertical axis and the distance to the epicenter on the horizontal axis

question

Tsunami

answer

A large wave along the sea surface triggered by an earthquake or large submarine slump

question

Wadati-Benioff zone

answer

A sloping band of seismicity defined by intermediate- and deep-focus earthquakes that occur in the down-going slab of a convergent plate boundary (subduction zone)

question

Amber

answer

Hardened (fossilized) ancient sap or resin

question

Archaea

answer

A kingdom of old bacteria, now commonly found in extreme environments like hot springs

question

Bacteria

answer

A type of tiny prokaryotic single-celled organism

question

Biomarker

answer

A measurable substance in an organism whose presence is indicative of some phenomenon such as disease, infection, or environmental exposure

question

Cambrian explosion

answer

See chapter 10

question

Cast

answer

Sediment that preserves the shape of a shell it once filled before the shell dissolved or mechanically weathered away

question

Eukarya

answer

A kingdom of organisms whose cells contain a nucleus; all plants and animals

question

Evolution

answer

Change in a species over a succession of generations

question

Extinction

answer

The species lived before but not longer exists

question

Extraordinary fossil

answer

A rare fossil relict, or trace, of the soft part of an organism

question

Fossil

answer

The remnant, or trace, of an ancient living organism that has been preserved in rock or sediment

question

Fossilization

answer

The process of forming a fossil

question

Gradualism

answer

The theory that evolution happens at a constant, slow rate

question

Macrofossil

answer

A fossil large enough to be seen with the naked eye

question

Mass extinction event

answer

A time when vast numbers of species abruptly vanish

question

Microfossil

answer

A fossil that can only be seen with a microscope

question

Mold

answer

A cavity in sedimentary rock left behind when a shell that once filled with space weathers out

question

3D

answer

Morphology

question

Natural selection

answer

The process by which the fittest organisms survive to pass on their characteristics to the next generation

question

Paleontologist

answer

Scientists that study fossils

question

Paleontology

answer

The study of fossils

question

Petrified wood

answer

Forms by the permineralization of wood, causing the wood to become chert

question

Phylogenetic tree

answer

A chart representing the ideas of paleontologists showing which groups of organisms radiated from which ancestors

question

Preservation potential

answer

The likelihood that an organism will be buried and eventually transformed into a fossil

question

Punctured equilibrium

answer

The hypothesis that evolution takes place in fits and starts; evolution occurs very slowly for quite a while and then, during a relatively short period, takes place very rapidly

question

Taxonomy

answer

The study and classification of the relationships between different forms of life

question

Theory of Evolution

answer

The process by which organisms change over time as a result of changes in heritable physical or behavioral traits

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