Earth Science Vocabulary

EARTH SCIENCE VOCABULARY

The following list of words and definitions is quite possibly the most comprehensive set of Earth science vocabulary known to a Jr. High. If there is an Earth Science word that you need a definition for and it is not here, please let me know!

aa -- a Hawaiian term for a lava flow that has a rough, jagged surface.

ablation -- as applied to glacier ice, the process by which ice below the snow line is wasted by evaporation and melting.

absolute time -- geologic time expressed in years before the present.

abundant metal -- iron, aluminum, magnesium, manganese, and titanium. Ores of the abundant metals only need to be 3 - 5 times as metal-rich as average rock.

abyssal plain -- large area of extremely flat ocean floor lying near a continent and generally over 4 km in depth.

acid -- a substance that produces positively charged hydrogen ions (H+) when dissolved in water.

acid rain -- the acidity in rain due to gases from internal combustion engines and coal- and oil-burning power plants.

aftershock -- an earthquake that follows and has its epicenter near a larger earthquake.

Andromeda -- the closest galaxy to the Milky way. It is approximately 2 million light-years away.

anemometer -- an instrument used to measure the speed of wind.

aquatic -- living in water.

aquifer -- a permeable region of rock or soil through which ground water can move.

aquitard -- a material of low permeability that greatly slows the movement of ground water.

arch -- forms along a coast as wave erosion cuts through a headland.

archaean -- an eon of geologic time extending from about 3.9 billion years to 2.5 billion years ago.

archipelago -- a group of islands; an expanse of water with scattered islands.

arid -- lacking in rainfall, very dry.

asteroid -- objects revolving around the sun that are too small and too numerous to be considered planets.

asthenosphere -- the weak or "soft" zone in the upper mantle just below the lithosphere, involved in plate movement and isostatic adjustments. It lies 70 to 100 km below the surface and may extend to a depth of 400 km.

atlas -- a collection of maps.

atmosphere -- the layer of gases (air), that surrounds a planet or moon.

atoll -- a roughly circular reef with an occasional small, low, coral sand island surrounding a shallow lagoon.

authigenesis -- the process by which new minerals form in a sediment or sedimentary rock during or after deposition.

axis -- the line formed by the intersection of the axial plane of a fold with a bedding plane, marking where the bed shows its maximum curvature.

back-arc basin -- the region between an island arc and the continental mainland, commonly with at least some oceanic crust on its floor.

back swamp -- swamp that forms in the low lying flood plain behind a levee.

backshore -- lies between high tide mark and the foot of the beach dune or the limit of effective wave action.

bar -- 1. A mass of sand, gravel, or alluvium deposited on the bed of a stream, sea, or lake, or at the mouth of a stream 2. A unit of pressure, approximately equal to atmospheric pressure at sea level.

barrier beaches -- long narrow beaches separated in many places from the mainland by lagoons.

barrier reef -- a coral reef separated from the mainland by a lagoon.

basalt -- highly mafic igneous volcanic rock, typically fine-grained and dark in color; rough volcanic equivalent of gabbro. Basalt is the most abundant volcanic rock in the Earth's crust.

basaltic - of or relating to or containing basalt, a dark, dense, extrusive rock that has a silica content of 40% to 50% and makes up most of the ocean floor.

base -- a substance that produces negatively charged hydroxide ions ( OH- ) in water and reacts with acids to form salts.

baseline study -- a study designed to collect critical data to be used for comparison or as a control in a later study.

basin -- 1. A low, bowl-shaped area of land surrounded by higher lands. 2. any large depression in which sediments are deposited.

beach -- temporary accumulations of sediments that collect between low and high water marks.

bedrock -- the rock beneath the soil.

Bering Land Bridge-- the vast tundra plain that was exposed between Asia and North America during the Last Glacial Maximum, about 21,000 years ago; it served as a migration route for people, animals, and plants. Also known as Beringia

biogenic sediment -- sediments produced directly by the life processes of plants or animals.

biogenic sedimentary rock -- a sedimentary rock composed primarily of biogenic sediments.

black hole -- the remains of an extremely massive star pulled into a small volume by the force of gravity.

black smoker -- a vent on the seafloor from which hydrothermal fluids are emitted. Upon mixing with seawater and cooling, the fluids precipitate a cloud of fine-grained sulfide minerals that resembles a cloud of black smoke.

body wave -- any seismic wave that travels through the body of Earth, rather than along its surface.

boundary -- the tectonic region in which two plates meet.

breakwater -- a protective wall built offshore and usually parallel to the shore.

caldera -- a large, basin-shaped volcanic depression, more or less circular in form. Typically steep-sided, found at the summit of a shield volcano.

calving -- the breaking away of ice from the front of the glacier when it ends in a lake or an ocean. Produces icebergs.

cartographer -- a person who makes maps.

casts -- fossils formed when water containing minerals leaks into a mold. The minerals harden to form a copy of the original structure or organism.

cave -- a natural open space underground, large enough for a person to enter. Most commonly occur by the dissolution of soluble rocks, generally limestone.

cementation -- the process by which a binding, or cementing, agent is precipitated in spaces among individual particles of a deposit. Common cementing agents are calcite, quartz, and dolomite.

Cenozoic -- the current geologic era, which began 66.4 million years ago and continues to the present.

chalk -- a soft compact calcite, CaCO3, with varying amounts of silica, quartz, feldspar, or other mineral impurities, generally gray-white or yellow-white and derived chiefly from fossil seashells.

channelization - - the straightening and/or deepening of a river channel.

chemical sediment -- sediment formed by chemical precipitation from water. Example: halite precipitated as the result of the evaporation of sea water.

chemical sedimentary rock -- a sedimentary rock made up of chemical sediments. Example: rock salt.

chlorophyll --the green pigment in the cells of many plants that enables them to use sunlight to convert carbon dioxide and water into carbohydrates in the process called photosynthesis.

chlorofluorocarbons (CFC's) -- gases that can be dissociated by solar radiation, which releases chlorine, which in turn destroys ozone.

cinder cone -- a conical volcano formed by the accumulation of pyroclastic debris around a vent.

cirque -- steep-walled hollow in a mountain side, shaped like an amphitheater, or bowl, with one side partially cut away. Place of origin of a mountain glacier.

clast -- an individual grain or constituent of a rock.

clastic -- refers to rock or sediments made up primarily of broken fragments of pre-existing rocks or minerals.

cleavage-- property possessed by certain rocks of breaking with relative ease along parallel planes or nearly parallel surfaces in their crystal structures where the bonds are weakest.

climate -- the average weather conditions of an area over many years, as measured by temperature, wind speed, and precipitation.

coal -- a sedimentary rock composed of combustible matter derived from the partial decomposition of plant material.

coast -- a narrow strip of land along the margin of the ocean extending inland for a variable distance from low water mark.

collisional Boundary -- where two plates collide to form mountains.

column -- a pillar formed as a stalactite and stalagmite meet.

comet -– a ball of ice and dust, whose orbit is a long, narrow ellipse.

compaction -- reduction of pore space between individual particles as the result of overlying sediments or of tectonic movements.

compass -- a device containing a free-swinging magnetic needle that is attracted to Earth's magnetic North Pole. Used to determine direction of travel.

compass Rose -- the symbol used on a map to indicate directions, both cardinal and ordinal.

compost -- to make a mixture of decaying organic materials to use as fertilizer.

compression fossil -- formed when an organism is flattened (compressed) and a thin film of organic material from its body is left in the rock.

conduction -- heat transport by direct transfer of energy from one particle to another, without moving the particle to a new location.

cone of depression -- a downward distortion or dimple in the water table that forms as a well pumps water faster than it can flow through the aquifer.

conserve -- to preserve, or to avoid wasteful use.

constellation -- a group of stars that appear to make a pattern in the sky. The Big Dipper is a constellation.

continent -- a thickened elevated region of Earth's crust that is mainly (but not entirely) above sea level.

continental arc -- a belt of volcanic mountains on the continental mainland that lie above a subduction zone.

continental crust -- the part of the crust that directly underlies the continents and continental shelves. Averages about 35 km in thickness, but may be over 70 km thick under largest mountain ranges.

continental divide -- a major drainage divide separating the drainage to one ocean from another.

Continntal Drift Theory -- The theory that states that the present-day continents are the fragmented pieces of preexisting larger landmasses called supercontinents.

continental rise -- the portion of the continental margin that lies between the abyssal plain and the continental slope. The continental rise is underlain by crustal rocks of the ocean basin.

continental shelf -- the portion of the continental margin that extends as a gently sloping surface from the shoreline seaward to a marked change in slope at the top of the continental slope . Seaward depth averages about 130 m.

continental slope -- that part of the continental margin that lies between the continental shelf and the continental rise. Slope relatively steep, 3o - 6o. The continental slope is underlain by crustal rocks of the continent.

convection -- heat transport by moving particles, and the thermal energy that they carry, to a new location.

convection cell -- a cyclical pattern of movement in a fluid body such as the ocean, the atmosphere, or the Earth's mantle, driven by density variations which in turn are the result of differences in temperature from one part of the fluid to another.

convergent boundary -- where one plate slides beneath another plate as the two are pushed together, a subduction zone.

Copernicus, Nicholas -– a famous scientist who proposed that the Sun was the center of the solar system not the Earth. (Heliocentrism)

core -- the innermost zone of Earth. It consists of two parts, an outer liquid section and an inner solid section, both chiefly of iron and nickel with about 10 percent lighter elements. It is surrounded by the mantle.

crater -- 1. A steep-walled, usually conical depression at the summit or on the flanks of a volcano, resulting from the explosive ejection of material from a vent. 2. A bowl-shaped depression with a raised, overturned rim produced by the impact of a meteorite or other energetic projectile.

creep -- the very slow, generally continuous downslope movement of soil and debris under the influence of gravity.

crevasse -- 1. Breach in a natural levee . 2. Deep crevice or open fracture in glacier ice.

crust -- the outermost layer of the Earth, varying in thickness from about 10 kilometers (6 miles) below the oceans, to 65 kilometers (about 40 miles) below the continents; represents less than 1 percent of the Earth's volume.

current speed -- the speed at which water flows.

crystal-- a geometrical form taken by a mineral, giving external expression to orderly internal atomic arrangement.

Darcy's law -- a formula describing the flow of water through an aquifer.

decomposition (chemical weathering) -- weathering processes that are the result of chemical reactions. Example: the transformation of orthoclase to kaolinite.

deflation -- a process of erosion in which wind carries off particles of dust and sand.

delta -- a low, nearly flat accumulation of sediment deposited at the mouth of a river or stream, commonly triangular or fan-shaped.

density -- the mass of an object divided by its volume.

denudation -- the sum of the processes that result in the wearing away or the progressive lowering of the Earth's surface by weathering, erosion, mass wasting, and transportation.

deposition -- any accumulation of material, by settling from water or air, chemical precipitation, evaporation from solution, etc.

desertification -- a process of land degradation initiated by human activity, particularly in the zones along the margins of deserts.

discharge -- in a stream, the volume of water passing through a channel in a given time.

disintegration (mechanical weathering) -- the processes of weathering by which physical actions such as frost wedging break down a rock into fragments, involving no chemical change.

divergent boundary -- where two plates are moving in opposite directions as in a mid-ocean ridge.

drainage basin -- he area from which a stream and its tributaries receives its water.

drainage divide -- the line that separates one drainage basin from another.

drift -- glacial deposits laid down directly by glaciers or laid down in lakes, ocean, or streams as result of glacial activity.

drought -- a period of dryness, that when prolonged, causes damage to crops; a shortage of water.

drylands -- a general term for semiarid and desert lands.

dust bowl -- an area subject to dust storms, especially south central United States .

dust devil -- a small, dust-bearing whirlwind.

dust storm -- a large volume of dust-sized particles lifted high into the atmosphere.

Earth -– (Latin- Terra, Greek- Gaia) Earth is named after the ancient Germanic Goddess of the soil. It is the third planet from the Sun.

Earth system -- a system involving continuous interaction of the solid Earth, the atmosphere, the oceans and living things.

eclipse -- the partial or complete blocking from view of one object by another.

ecosystem -- a community of plants and/or animals and its physical environment, regarded as a unit.

elevation -- the height of a place above sea level.

El Nino -- a time of unusual winds and currents in the Pacific Ocean . El Nino generally causes warmer-than-normal sea surface temperatures and increased rainfall and storm activity.

eon -- the primary division of geologic time which are, from oldest to youngest, the Hadean, Archean, Proterozoic, and Phanerozoic eons.

epicenter -- the point on the Earth's surface that is directly above the focus of an earthquake.

epicenter -- the point on the Earth's surface directly above the focus of an earthquake.

epoch -- a division of geologic time next shorter than a period. Example: the Pleistocene epoch is in the Quaternary period.

equator -- an imaginary circle around the earth that represents the halfway mark between the North and South Poles and establishes the boundary between the Northern and Southern Hemispheres.

equinox -– the two days of the year on which neither hemisphere is tilted toward or away from the sun.

era -- a division of geologic time next smaller than the eon and larger than a period. Example: The Paleozoic era is in the Phanerozoic eon and includes, among others, the Devonian period.

erosion -- the processes (mechanical and chemical) responsible for the wearing away, loosening, and dissolving of materials of the Earth's crust.

escarpment -- a steep or vertical cliff, either above or below sea level.

estuary -- an area where fresh water comes into contact with seawater, usually in a partly enclosed coastal body of water; a mix of fresh and salt water where the current of a stream meets the tides.

erratic -- a stone or boulder, glacially transported from place of origin and left in an area of different bedrock composition.

eustatic change in sea level -- a worldwide change in sea level, such as caused by melting glaciers.

exotic river -- a river that is able to maintain its flow through a desert because of water received from outside the desert.

extrusive -- Igneous. Antonym of intrusive. Synonym of volcanic. Pertaining to igneous rocks or features formed from lava released on the Earth's surface.

fault -- a fracture or zone of fractures along the boundaries of tectonic plates.

fetch -- distance over which wave-forming winds blow.

firn (névé) -- granular ice formed by the recrystallization of snow. Intermediate between snow and glacier ice.

fissure eruption -- an eruption of lava that takes place from a fracture, usually without producing a cone.

fjord -- a glaciated valley now flooded by the sea.

flash flood -- a flood that rises and falls very rapidly.

flood - the peak flow of water that tops the banks of a stream channel.

floodplain - the area bordering a stream over which water spreads when the stream tops its channel banks.

fluctuate -- to change back and forth uncertainly.

focus -- the initial point within the Earth that ruptures in an earthquake, directly below the epicenter. The point within the Earth which is the center of an earthquake, at which strain energy is first released and converted to elastic wave energy.

fold -- bent rock strata.

fold and thrust mountains -- mountains, characterized by extensive folding and thrust faulting, that form at convergent plate boundaries on continents.

foliated-- the presence of layers in some rocks caused by parallel alignment of minerals.

foreshock -- a minor tremor that precedes an earthquake. An increase in seismicity may signal that a major release of strain energy is about to occur.

fossil -- evidence in rock of the presence of past life, such as a dinosaur bone, an ancient clam shell, or the footprint of a long-extinct animal as well as life history artifacts.

fossil fuel -- a hydrocarbon (coal or petroleum) that can be extracted from the Earth for use as a fuel. Fossil fuels are non-renewable energy sources.

fracture-- the way in which a rock or mineral breaks in random patterns rather than cleaving

fringing reef -- a coral reef attached directly to the mainland.

frost wedging -- a type of disintegration in which jointed rock is forced apart by the expansion of water as it freezes in fractures.

galaxy -– a giant structure that contains hundreds of billions of stars.

Galileo -– the first scientist to make systematic use of the telescope in looking at the heavens.

gemstone -- Any of various minerals prized for beauty, durability, and rarity. A few noncrystalline materials of organic origin (e.g., pearl, red coral, and amber) also are classified as gemstones.

geologic column -- the arrangement of rock units in the proper chronological order from youngest to oldest.

geologic time scale -- the chronological sequence of units of Earth time.

geology -- the science that deals with the study of the planet Earth--the materials of which it is made, the processes that act to change these materials from one form to another, and the history recorded by these materials; the forces acting to deform the outer layers of the Earth and create ocean basins and continents.

geothermal energy -- heat extracted from the Earth for use as an power source.

geyser -- a type of thermal spring which ejects water intermittently with considerable force.

glaciation -- the formation, advance and retreat of glaciers and the results of these activities.

lacier -- a mass of ice, formed by the recrystallization of snow, that flows forward, or has flowed at some time in the past.

Global Positioning System (GPS) -- A system that uses a constellation of 24 satellites, their ground stations, and individual GPS receivers to accurately locate points on Earth.

global warming -- the prediction that climate will warm as a result of the addition to the atmosphere of humanly produced greenhouse gases.

Gondwana -- the southern portion of the late Paleozoic supercontinent known as Pangea. It means, literally "Land of the Gonds" (a people of the Indian subcontinent).The supercontinent existed from Cambrian to Jurassic time, mainly composed of South America, Africa, Madagascar, India, Antarctica, and Australia.

granitic -- Pertaining to or composed of granite, a coarse-grained igneous rock dominated by light-colored minerals, consisting of about 50 percent orthoclase, 25 percent quartz, and balance of feldspars and ferromagnesian silicates. Granite is commonly found on continents but virtually absent from the ocean basins.

gravity -– the attractive force between two objects; its magnitude depends on their masses and the distance between them.

Greenhouse Effect -- the effect of water and carbon dioxide absorbing outgoing infrared radiation, raising a system's temperature. The term is generally used with reference to the Earth's temperature, although it can also be applied to other systems, such as greenhouses and automobiles.

greenhouse gases -- gases (primarily water and carbon dioxide, but also a variety of sulfur and nitrogen compounds and gaseous hydrocarbons) that trap the Sun's heat in the atmosphere.

groin -- a wall built out from the shore, usually at perpendicular to it to trap sand carried by longshore currents .

groove -- a broad, deep, generally straight furrow carved in bed rock by the abrasive action of debris embedded in a moving glacier. Larger and deeper than a glacial striation.

ground moraine -- till deposited from main body of glacier during ablation.

groundtruthing -- verifying assessments made from satellite data by doing direct, "on-the ground" measurements.

ground water -- water beneath the Earth's surface.

habitat -- the environment where a particular plant or animal is normally found.

Hadean -- the oldest eon in Earth history, extending from the origin of the Earth to about 3.9 billion years ago.

Hale-Bopp -- a comet that passed Earth in 1997 and won't return to the inner solar system until the year 4377.

hardness -- the resistance of a mineral to scratching, as measured by the Mohs scale.

hardpan -- a general term for a relatively hard layer of soil at or just below the ground surface, cemented by silica, iron oxide, calcium carbonate, or organic matter.

hemisphere -- Either the northern or southern half of the Earth as divided by the equator, or the eastern or western half as divided by a meridian.

hot spot -- a region of high heat flow on the Earth's surface, thought to lie above a mantle plume .

hydrologic cycle --the pattern of water circulation from the ocean to the atmosphere to the land and back to the ocean.

humid -- containing moisture.

humus -- the generally dark, more or less stable part of the organic matter in a soil, so well decomposed that the original sources cannot be identified.

ice sheet -- a broad, mound-like mass of glacier ice that usually spreads radially outward from a central zone.

ice shelf -- a floating ice sheet extending across water from a land-based glacier.

icecap -- a small ice sheet.

igneous rock -- a rock that has crystallized from a molten state.

inertia -– the tendency of a moving object to continue in a straight line or a stationary object to remain in place.

inner core -- the solid innermost part of the core with a diameter of a little over 1,200 km.

intensity -- a measure of the size of an earthquake in terms of the damage it causes.

intertidal zone -- the region of a shore that is covered at high tide and exposed at low tide.

intrusive -- Plutonic. Antonym of extrusive. Pertaining to igneous rocks or features formed by the emplacement of magma in pre-existing rocks.

island arc -- a curved belt of volcanic islands lying above a subduction zone.

isostasy -- the condition of equilibrium, comparable to floating, of units of the lithosphere above the asthenosphere.

isostatic change in sea level -- a sea level change due to change in load on Earth's crust.

isthmus -- a narrow strip of land that has water on either side and connects two larger bodies of water.

jetty -- similar to a groin but built to keep sand out of a harbor entrance.

Jupiter -– Jupiter is named after the Roman king of the gods. It is the fifth planet from the Sun.

karst -- a landscape that develops from the action of ground water in areas of easily soluble rocks. It is usually characterized by caves, underground drainage and sinkholes.

kettle - a depression in the ground formed by the melting of a block of glacier ice buried or partially buried by drift.

lahar -- a mudflow composed chiefly of pyroclastic material on the flanks of a volcano.

landforms -- shapes, like mountains or hills that make up the Earth's surface.

latitude -- imaginary lines on a map or globe that measure distance in degrees north or south of the equator. Latitude lines extend horizontally, from east to west on a globe.

Laurasia -- a supercontinent that existed from the Jurassic to Early Tertiary after splitting from Pangea; composed of Laurentia, Baltica, Avalonia, (modern North America, Scandinavia, Greenland, Western and Central Europe); eventually fragmented into Eurasia and North America in the Tertiary with the opening of the North Atlantic Ocean. The northern portion of the late Paleozoic supercontinent called Pangea.

lava -- any molten material that is extrusive or volcanic, or the rock that forms from a molten extrusive. Molten rock that flows at the Earth's surface.

lava dome -- a steep-sided rounded extrusion of highly viscous lava squeezed out from a volcano and forming a dome-shaped or bulbous mass above and around the volcanic vent. The structure generally develops inside a volcanic crater.

lava flood (plateau basalt) -- a term applied to large areas of basaltic lava presumably extruded from fissures.

lava lake -- a lake of lava, usually basaltic, in a volcanic caldera.

legend -- a guide to reading a map that typically contains distance scales, arrows indicating direction, and/or explanations of symbols used.

levees -- banks of sand and silt along stream bank built by deposition in small increments during successive floods.

light-year -- the distance light travels through a vacuum in one year.

liquefaction -- the transformation of a soil from a solid to a liquid state as the result of increased pore pressure.

lithification -- the process by which an unconsolidated deposit of sediments is converted in to solid rock.

lithosphere -- the rigid outer shell of the Earth. It includes the crust and uppermost mantle and is on the order of 100 km in thickness.

loess -- deposits of wind-borne dust.

longitude -- imaginary lines on a map or globe that measure distance in degrees east or west of the prime meridian. Longitude lines extend vertically, from pole to pole on a globe.

luster -- the reflection of light on a given mineral's surface, classified by intensity and quality.

magma -- molten rock, containing dissolved gases and suspended solid particles. At the Earth's surface, magma is known as lava.

magnetic equator -- lies half way between the north and south magnetic poles.

magnetic polarity -- the direction, north (normal) or south (reversed), that a magnetic compass needle points.

magnetic pole -- the point on the Earth's surface where a magnetic needle points vertically downward (north magnetic pole) or vertically upward (south magnetic pole).

magnitude -- a measure of the strength of an earthquake based on the amount of movement recorded by a seismograph . compare Richter scale.

mantle -- that portion of the Earth below the crust and reaching to about 2,780 km, where a transition zone of about 100 km thickness separates it from the core.

marine Chronometer -- a portable time keeper with a mechanism for ensuring accuracy and adjusting itself, used for determining longitude at sea.

Mars -–Mars is named after the Roman god of war. It is the fourth planet from the Sun.

meander -- a sharp bend, loop or turn in a stream's course. When abandoned, it is called a meander scar or an oxbow.

Mercury -– Mercury is named after the Roman messenger of the gods. It is the closest to the Sun.

mesosphere -- a zone in the Earth between 400 and 670 km below the surface separating the upper mantle from the lower mantle.

Mesozoic -- an era of time during the Phanerozoic eon lasting from 245 million years ago to 66.4 million ago.

metamorphic rock -- a rock changed from its original form and/or composition by heat, pressure,shearing stress, or chemically active fluids, or some combination of them.

meteoroid -– a chuck of rock or dust in space.

mid-ocean ridges -- elongated rises on the ocean floor where basalt periodically erupts, forming new oceanic crust.

Milky Way -- the galaxy where Earth is located.

mineral -- a naturally occurring inorganic solid that has a well-defined chemical composition and in which atoms are arranged in an ordered fashion.

mineral deposit -- any natural concentration of a valuable material in the Earth's crust, whether that material can be extracted profitably or not.

Modified Mercalli Scale -- a commonly used scale of earthquake intensity.

moon -– a planetary satellite.

moraine -- a mound or ridge of sediment deposited by a glacier.

natural resources -- materials that are found in nature that are useful or necessary for people to live.

nautical mile -- a unit of length used in sea navigation based on the length of 1 minute of arc on a great circle. On Earth, 1 minute of latitude.

nebula -– a large amount of gas and dust in space, spread out in an immense volume.

Neptune -– Neptune is named after the Roman god of the sea. It is the eighth planet from the Sun.

nonfoliated- no identifiable layers of minerals in a rock sample

nova -– (Supernova) -- the explosion of a dying giant or supergiant star.

nuée ardente -- a dense, hot (sometimes incandescent) cloud of volcanic ash and gas produced in a Pelean eruption.

nutrient -- an ingredient in a food or other substance that nourishes or promotes growth.

observatory -– a building that contains one or more telescopes.

oceanic crust -- the Earth's crust underlying the ocean basins which is formed at mid-oceanic ridges. It is typically 5 to 10 kilometers thick composed of basalt.

oceanic trench -- deep steep-sided depression in the ocean floor caused by the subduction of oceanic crust beneath either other oceanic crust or continental crust.

open pit mining -- surficial mining, in which the valuable rock is exposed by removal of overlying rock or soil.

ore -- the naturally occurring material from which a mineral or minerals of economic value can be extracted at a profit.

ore deposit -- a continuous well-defined mass of material of sufficient ore content to make extraction economically feasible. compare mineral deposit.

orogeny -- the process of mountain building.

outcrop -- any place where bedrock is visible on the surface of the Earth.

outer core -- the outermost part of the core. It is liquid, about 1,700 km thick, and separated from the inner, solid core by a transition zone about 565 km thick.

oxbow -- an abandoned meander .

oxbow lake -- a lake in an abandoned meander.

ozone -- a molecule composed of three atoms of oxygen and mostly found in the stratosphere. Though beneficial in the upper atmosphere, at ground level, ozone is called photochemical smog, and is a respiratory irritant and considered a pollutant.

ozone depletion -- destruction of the ozone layer caused by the release of CFC's (chlorofluorocarbons) into the atmosphere which react chemically with ozone and break it down into different gases.

ozone layer -- an atmospheric shield providing the Earth with protection from ultra-violet rays which can cause sun burn, skin cancer and the destruction of the delicate plant life which supports the planet's food chain.

p- wave (primary wave, compressional wave) -- a seismic body wave that involves particle motion, alternating compression and expansion, in the direction of wave propagation. It is the fastest seismic wave. compare S-wave .

pahoehoe -- a Hawaiian term for a basaltic lava flow with a smooth, or ropy surface.

Paleozoic -- an era of geologic time lasting from 570 to 245 million years ago.

Pangea -- a supercontinent that existed from the the end of the Permian to the Jurassic, 300 to 200 million years ago, assembled from large continents like Euramerica, Gondwana, and Siberia, as well as smaller landmasses like the Cathaysian and Cimmerian terranes; Greek for "all lands."

particulate air pollution --the very small particles of dirt, soot, and other pollutants that are present in the air.

pathogen -- a disease-causing organism or entity, such as a bacterium or virus.

peat -- A deposit of partly decayed plant remains in a very wet environment; marsh or swamp deposit of plant remains containing more than 50 percent carbon.

Peléan eruption --a type of volcanic eruption characterized by nuées ardentes and the development of lava domes.

period -- in the geologic time scale a unit of time less than an era and greater than an epoch. Example: The Tertiary period was the earliest period in the Cenozoic era and included, among others, the Eocene epoch.

permafrost -- soil conditions prevailing in area whose mean annual temperature is 0o C.

petroleum -- a general term including both oil and natural gas.

pH -- a measure of acidity.

Phanerozoic -- the most recent eon of geologic time beginning 570 million years ago and continuing to the present.

Pillow Lava -- lava extruded beneath water characterized by pillow shapes.

pipe -- a vertical conduit through the Earth's crust below a volcano, through which magma has passed.

plain -- a large area of flat or nearly flat land.

plate -- a rigid segment of the Earth's lithosphere that moves horizontally and adjoins other plates along zones of seismic activity. Plates may include portions of both continents and ocean basins.

plate boundaries -- the zones of seismic activity long which plates are in contact.

plate tectonics -- The theory of Plate Tectonics states that the Earth's crust is fragmented into a dozen or more large and small pieces floating on a semi-molten mantle.

Pluto -– Pluto is named after the Roman god of the Underworld. No longer considered a planet.

plutonic -- Synonym of intrusive. Antonym of volcanic. Applies to igneous rocks formed beneath the surface of the Earth; typically with large crystals due to the slowness of cooling.

pollutant -- a waste material that contaminates air, water, or soil.

pothole -- a hole or basin cut into bedrock of a stream by the abrasive action of pebbles and sand swirled by turbulent stream flow.

prairie -- flat land covered with tall grass and wildflowers.

Precambrian -- an informal term to include all geologic time from the beginning of the Earth to the beginning of the Cambrian period 570 million years ago.

precipitation -- any form of water, such as rain, sleet, or snow, that falls to Earth's surface.

primary productivity -- the production of living matter by organisms that make food using sunlight or chemicals. Usually expressed as grams of carbon per square meter per year.

Prime Meridian -- the great circle on the Earth's surface passing through The North and South Poles, which is considered 0 degrees longitude. The prime meridian passes through Greenwich , England , and is used as a reference point for measuring longitude east and west.

Proterozoic -- the geologic eon lying between the Archean and Phanerozoic eons, beginning about 2.5 billion years ago and ending about 0.57 billion years ago.

Proxima Centauri -- the closest star to Earth besides the sun. It is approximately 4 light years away.

pyroclastic -- pertaining to clastic material formed by volcanic explosion or aerial expulsion from a volcanic vent.

quarrying -- the process by which building stone, usually in blocks or sheets, is extracted from the Earth.

radiation -- (Electromagnetic radiation) -- energy that travels through space in the form of waves without the intervention of matter, as in the transport of heat from the Sun to the Earth.

rainforest -- woodland that usually gets at least 100 inches of rain each year.

rain shadow deserts -- deserts formed by blocking moisture-bearing winds with mountain barriers.

rapids -- turbulent stream water flow down a steep gradient, but not as steep as in a waterfall.

reef -- a large ridge or mound-like structure within a body of water that is built by calcareous organisms such as corals, red algae, and bivalves.

region -- a large area with common features that set it apart from other areas.

renewable resources -- living parts of the environment that can renew or replace themselves.

reserves -- that portion of the resources for a valuable mineral commodity that can be extracted from the Earth at a profit today.

reservoir rock -- any porous and permeable rock that yields oil or natural gas.

resources -- the reserves of a valuable mineral commodity plus all other mineral deposits that may eventually become available, even those that are presumed to exist but have not yet been discovered and those that are not economically or technologically exploitable at the moment.

Richter scale -- a commonly used measure of earthquake magnitude, based on a logarithmic scale. Each integral step on the scale represents a tenfold increase in the extent of ground shaking, as recorded on a seismograph.

rift (graben) -- a valley caused by extension of the Earth's crust. Its floor forms as a portion of the crust moves downward along normal faults.

rock -- an aggregate of one or more minerals in varying proportions.

rock cycle -- the concept of a sequence of events involving the formation, alteration, destruction and reformation of rocks as a result of geologic processes.

rockslide (rock avalanche) -- a slide involving a downward and usually sudden movement of newly detached segments of bedrock sliding or slipping over an inclined surface of weakness such as a bedding plane, fault plane, or joint surface.

rockfall -- the sudden fall of one or more large pieces of a rock from a cliff.

runoff -- the precipitation that runs directly off the surface to stream or body of standing water.

s- wave (secondary wave , shear wave) -- a seismic body wave that involves particle motion from side to side, perpendicular to the direction of wave propagation. S-waves are slower than P-waves and cannot travel through a liquid.

salinity -- the amount of dissolved salt in water.

salinization -- a process by which salts accumulate in soil.

sand dune -- an accumulation of wind driven sand into a distinctive shape.

sandstorm -- a blanket of wind-driven sand with an upper surface about a meter above ground level.

satellite -- any object that revolves around another object in space.

Saturn -- Saturn is named after the Roman god of the harvest. It is the sixth planet from the Sun.

scale-- the relationship between distances in the area being mapped and distances in the map itself.

scientific model -- a detailed mathematical description of the cause-and-effect relationships between events that can be used to predict or explain other such events.

scour -- to wash or scrub away.

secchi disk -- a tool for measuring the relative clarity of water.

seafloor spreading -- the process by which ocean floors spread laterally from crests of main ocean ridges. As material moves laterally from the ridge, new material replaces it along the ridge crest by welling upward from the mantle.

seamount -- a volcanic mountain on the seafloor. If flat-topped, it is a guyot.

seastack -- an isolated, steep-sided, rocky mass or island just offshore from a rocky headland, usually on a shore platform.

sediment -- any solid material that has settled out of a state of suspension in liquid.

sedimentary rock -- rock formed from the accumulation of sediment, which may consist of fragments and mineral grains of varying sizes from pre-existing rocks, remains or products of animals and plants, the products of chemical action, or mixtures of these.

seismic gap -- a segment of an active fault zone that has not experienced a major earthquake during a time period when most other segments of the zone have. They are generally regarded as having a higher potential for future earthquakes.

seismic sea wave (tsunami) -- a sea wave produced by any large-scale, short duration disturbance on the seafloor, commonly a shallow submarine earthquake but possibly also a submarine slide or volcanic eruption.

seismograph -- an instrument that detects, magnifies, and records vibrations of the Earth, especially earthquakes.

seismology -- the study of earthquakes, and of the structure of the Earth by both natural and artificially generated seismic waves.

seismoscope -- an instrument that merely indicates the occurrence of an earthquake.

sextant -- an astronomical instrument for measuring angles, primarily altitude of celestial bodies to determine latitude.

shield volcano -- a volcano in the shape of a flattened cone, broad and low, built by very fluid flows of basaltic lava.

shore -- the seaward edge of coast between low tide and effective wave action.

shoreline -- the line separating land and water.

silicate- One of several rock-forming minerals that contain at least 95% silica (quartz). and usually one or more other common elements.

siltation -- deposition of fine mineral particles (silt) on the beds of streams or lakes.

sinkhole -- a natural depression in the surface of the land caused by the collapse of the roof of a cavern or subterranean passage, generally occurring in limestone regions.

smelting -- the process of removing metal from ore.

snow line -- the elevation at which snow persists throughout the year.

sod -- a thick layer of soil.

soil -- all unconsolidated materials above bedrock. Natural earthy materials on the Earth's surface, in places modified or even made by human activity, containing living matter, and supporting or capable of supporting plants out of doors.

solar system -- the Sun with all the celestial bodies that revolve around it.

solstice -- the two days of the year on which the noon sun is directly overhead at either 23.5° South or 23.5° North.

specific gravity- Ratio between weight of given volume of material and weight of equal volume of pure water.

spring -- occurs at the intersection of the water table with the ground surface.

stalactite -- an icicle-shaped accumulation of dripstone hanging from cave roof.

stalagmite -- a post of dripstone growing up from a cave floor.

star -- a hot, gaseous, self-luminous celestial body, as the Sun.

steppe -- a flat, dry plain covered with short grass.

storm surge -- a ridge of high water associated with a hurricane and which floods over the shore .

stormwater runoff -- Water that flows across watersheds during and immediately after severe rainstorms. In populated areas, stormwater runoff is often water that cannot be handled by existing sewer systems. Stormwater runoff is the leading source of water pollution in the United States.

stratification -- the accumulation of material in layers or beds.

stratovolcano (composite volcano) -- a volcano that is composed of alternating layers of lava and pyroclastic material, along with abundant dikes and sills. Viscous, intermediate lava may flow from a central vent. Example: Mt. Fuji in Japan.

stratum -- a layer of sedimentary rock; plural is strata.

streak- The color of a mineral in its powdered form obtained from scraping a sample on a ceramic plate

striations -- scratches, or small channels, gouged by glacier action. Occur on boulders, pebbles, and bedrock. Striations along bedrock indicate direction of ice movement.

strip mining -- open pit mining, typically for coal.

subduction -- the process of one plate descending beneath another.

subduction zone -- a narrow, elongate region in which one lithospheric plate descends relative to another.

subtropical deserts -- deserts in zones of descending air between 25 degrees and 30 degrees north and south latitude.

Sun -- (Latin- Sol, Greek- Helios)the closest star to Earth. It is a giant ball of gas without any solid surface.

superposition -- a statement of relative age in layered rocks: In a series of sedimentary rocks that has not been overturned, the topmost layer is always the youngest and the bottommost layer is always the oldest.

surf -- produced as a wave steepens and falls forward as the wave nears the shore.

suspended load -- the amount of material a stream carries in suspension.

suspension -- a method of sediment transport in which the turbulence of a fluid is able to keep particles supported in the fluid.

swash and back wash -- the uprush of a wave onto the beach followed by the return flow of the water down the beach slope in the intervals between waves.

swells -- the persistence of wind-formed waves after wind ceases.

tectonic Plates -- enormous, thick sheets of rock that are part of the Earth's upper mantle that move and adjoin each other along zones of seismic activity. Many tectonic plates extend underneath both continents and sea floor.

telescope -- a device built to study distant objects by making them appear closer.

tell -- an artificial hill formed by the debris of successive human settlements.

terrestrial -- living on land.

thermal spring -- a spring whose temperature is 6.5o C or more above mean annual air temperature.

thrust fault -- a reverse fault on which the dip angle of the fault plane is 15 degrees or less.

tidal delta -- a delta formed at both sides of a tidal inlet.

tidal inlet -- a waterway from open ocean into a lagoon.

tide -- the rise and fall of sea level caused by the gravitational pull of the Sun and Moon on the Earth.

till (unstratified drift) -- Glacial drift composed of rock fragments that range from clay to boulder size and randomly arranged without bedding.

transcontinental -- extending across a continent.

transform boundary -- a plate boundary in which plates on opposite sides of the boundary move past each other in opposite directions. The San Andreas fault of California is a good example.

trench -- a narrow, steep-walled depression in the ocean floor, much deeper than the adjacent ocean and associated with a subduction zone.

triangulation --the method of locating an epicenter by determining how far it lies from three widely separated seismographs.

u-shaped valley -- a valley carved by glacier erosion and whose cross-valley profile has steep sides and a nearly flat floor, suggestive of a large letter "U".

Uniformitarianism -- the principle that states the processes operating to change the Earth in the present also operated in the past.

universe -- all of space and everything in it.

Uranus -–Uranus is named after the Roman god of the sky. It is the seventh planet from the Sun.

urban -- the areas of, in, or constituting a city.

Venus -– (Greek-Aphrodite)named after the Roman goddess of love. It is the planet closest in size to Earth and the second planted from the Sun.

vesicle -- a cavity in a lava, formed by the entrapment of a gas bubble during solidification of the lava.

viscosity -- the internal resistance to flow in a liquid.

volcanic -- applies to igneous rocks that cool on the surface of the Earth, including beneath water; typically with small crystals due to the rapidity of cooling. Synonym of extrusive. Antonym of plutonic.

volcanic ash -- the dust-sized, sharp-edged, glassy particles resulting from an explosive volcanic eruption.

volcano -- a vent in the surface of the Earth, from which lava, ash, and gases erupt.

water clarity -- the level of light that penetrates through water.

watershed -- an area of land that delivers runoff water, sediment, and dissolved substances to surface water bodies, such as rivers or lakes. All watersheds consist of boundaries, a basin and collection areas.

water table -- the surface between the zone of saturation and the zone of aeration.

waterfall -- the perpendicular or very steep descent of a stream.

wave crest -- the top of a wave.

wave height -- the vertical distance between the crest and adjacent trough of a wave.

wave length -- the distance between two successive wave crests or troughs.

wave trough -- the low spot between two successive waves.

weathering -- the physical, chemical, and biological processes by which rock at or near the Earth's surface is broken down into smaller pieces.

wind farm -- an area in which a large number of windmills have been erected to generate electrical power.

zone of aeration -- the area immediately below the ground surface within which pore spaces are partially filled with water and partially filled with air.

zone of leaching -- the upper horizons in a soil, through which gravitational moisture travels, removing soluble decomposition products.

zone of saturation -- the zone below the zone of aeration in which all pore spaces are filled with water.