Earth Science/Biology Vocab

aa

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

 absolute time

 geologic time expressed in years before the present

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.

archipelago

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

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.

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.

barrier reef

a coral reef separated from the mainland by a lagoon.

basin

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

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.

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.

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.

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.

 chemical sediment

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

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.

coal

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

collisional Boundary

where two plates collide to form mountains.

 compaction

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

  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.

 continent

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

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.

 convection -

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

convergent boundary

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

 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.

 crystal

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

decomposition (chemical weathering)

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

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.

 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

-- the area from which a stream and its tributaries receives its water.

drift

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

dust bowl

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

dust storm

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

Earth system

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

 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.

 epicenter

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

  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.

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.

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.

fjord

a glaciated valley now flooded by the sea.

 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.

 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.

 fracture-

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

  frost wedging

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

 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.

glacier

 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.

 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.

 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.

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.

 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.