Glossary Database

Select a Letter to view the associated terms.

 Glossary Term: 


 Labial scale  Scale that borders the lip in reptiles (Peters 1964).
 Laccolith  A concordant igneous intrusion that has arched up the strata into which it was injected, so that it forms a pod-shaped or lens-shaped body with a generally horizontal floor.
 Lactate  to secrete milk. (Lactation)
 Lacustrine  Pertaining to, produced by, or inhabiting a lake or lakes. Such as lacustrine sands or lacustrine fauna.
 Lag deposit  A residual accumulation of coarse fragments that remains on the surface after finer material has been removed by wind.
 Lagoon  A shallow body of sea water separated from the open ocean by a barrier island or reef.
 Lahar  A volcanic debris flow.
 Lamina (pl. laminae)  A layer of sediment less than 1 cm thick.
 Laminae  The scales for the epidermal plates of the shell of turtles (Peters 1964).
 Laminar flow  A type of flow in which the fluid moves in parallel lines. Contrast with turbulent flow.
 Landform  Any feature of Earth's surface having a distinct shape and origin. Landforms include major features (such as continents, ocean basins, plains, plateaus, and mountain ranges) and minor features (such as hills, valleys, slopes, drumlins, and dunes). Collectively, the landforms of Earth constitute the entire surface configuration of the planet.
 Landslide  A general term for relatively rapid types of mass movement, such as debris flows, debris slides, rock slides, and slumps.
 Lateral  Of or pertaining to the side. Sideways.
 lateral line  A sensory structure along each side of many fishes marked by scales with pores opening into an underlying canal.
 Lateral moraine  An accumulation of till deposited along the side margins of a glacial valley. It accumulates as a result of mass movement of debris on the sides of the glacier.
 Laterite  A soil that is rich in oxides of iron and aluminum formed by deep weathering in tropical and subtropical areas.
 Latitude  Distance measured in degrees, north and south from the equator. All lines of latitude are parallel to each other.
 Laurasia  The ancient continental land mass that is thought to have split apart to form Europe, Asia, North America, and Greenland.
 Lava  Magma that reaches Earth's surface.
 Lava cone  A volcanic cone composed primarily of lava flows. Sometimes the cone will have a convex profile due to flank flows of viscous lava
 Lava dome  Bulbous lava flow or viscous plug of lava piled near its vent. Most are made of rhyolite.
 Lava Flow  Lava flows are masses of molten (liquid) rock that pour onto the Earth's surface during an eruption. Moving lava and the resulting solidified deposit are referred to as lava flows.
 Lava tube  A hollow space beneath the surface of a solidified lava flow, formed by the withdrawal of molten lava after the formation of the surficial crust.
 Leach  To dissolve and remove the soluble constituents of a rock or soil.
 Leachate  A solution produced by leaching. Example: water that has seeped through a waste disposal site and thus contains in solution various substances derived from the waste material.
 Lee slope  The part of a hill, dune, or rock that is sheltered or turned away from the wind. Synonymous with slip face.
 Legume  A specific type of plant, belonging to the family Fabaceae (formerly Leguminosae). These plants produce their fruit as a pod and generally possess nitrogen-fixing bacteria in nodules on their roots. Examples of legumes include peas, beans, and alfalfa.
 Lek  Communal courtship grounds (Gill 1995)
 Lepidoptera  a large order of scaly-winged insects including the butterflies, skippers, and moths, often brightly colored and having a coiled sucking proboscis (Morris 1992).
 Lethargic  the state of being abnormally drowsy or stupor (Morris 1992).
 Levee, natural  A broad, low embankment built up along the banks of a river channel during floods.
 Lichen  the common name for any member of the group Lichenes, occurring as fungal and algae cells in symbiotic union and growing in various forms of rocks or trees (Morris 1992).
 Limb  The flank, or side, of a fold.
 Limestone  A sedimentary rock composed mostly of calcium carbonate (CaCO3).
 Lineament  A topographic feature or group of features having a linear configuration. Lineaments commonly are expressed as ridges or depressions or as an alignment of features such as stream beds, volcanoes, or vegetation.
 Linear  Pertaining to a straight line.
 Liquefaction  Transformation of water-saturated granular material from the solid state to a liquid state.
 Liquid  The state of matter in which a substance flows freely and lacks crystal structure. Unlike a gas, a liquid retains the same volume independent of the shape of its container.
 Lithification  The processes by which sediment is converted into sedimentary rock. These processes include cementation and compaction.
 Lithosphere  The relatively rigid outer zone of Earth, which includes the continental crust, the oceanic crust, and the part of the upper mantle lying above the weaker asthenosphere.
 Litter  1. multiple offspring produced at a single birth by a multiparous animal. 2. a spongy layer of twigs, leaves, bark and organic debris covering the floor of a forest (Morris 1992).
 Littoral zone  The area of shallow fresh water in which light penetrates to the bottom and nurtures rooted plants (Morris 1992).
 Load  The amount of sediment and dissolved matter contained in a stream, river, current, glacier, wind, etc.
 Loam  A rich soil (Morris 1992).
 Loess  1.)Unconsolidated, wind-deposited silt and dust. 2.)An extremely fertile, fine-grained loam composed of quartz, feldspar, hornblende, mica, and clay; deposited by the wind during the Pleistocene Age. It originates in arid regions from glacial outwash (Morris 1992).
 Logarithm  The exponent expressing the power to which a fixed number must be raised to produce a given number.
 Longitude  Distance east or west on the earth's surface measured from the prime meridian and expressed in degrees or time.
 Longitudinal dune  An elongate sand dune oriented in the direction of the prevailing wind.
 Longitudinal profile  The profile of a stream or valley drawn along its length, from source to mouth.
 Longitudinal wave  A seismic body wave in which particles oscillate along lines in the direction in which the wave travels. Synonymous with P wave.
 Longshore current  A current in the surf zone moving parallel to the shore. Longshore currents occur where waves strike the shore at an angle.
 Longshore drift  The process in which sediment is moved in a zigzag pattern along a beach by wash and backwash of waves approaching the shore obliquely.
 Love wave (L-wave)  A surface wave in which the individual particles of the material move back and forth in a horizontal plane perpendicular to the direction of wave movement.
 Low-grade metamorphism  Metamorphism that is accomplished under low or moderate temperature and low or moderate pressure.
 Lunar  Pertaining to the moon.
 Lungworm  the common name for any of various parasitic nematodes that infect the lungs of vertebrates, principally domestic animals (Morris 1992).