Page 727 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

Glossary G-8
Joint (14) A fracture or separation in rock that occurs without displacement of the sides; increases the surface area of rock exposed to weathering processes.
June (summer) solstice (2) See Summer (June) solstice.
Kame (17) A depositional feature of glacia- tion; a small hill of poorly sorted sand and gravel that accumulates in crevasses or in ice- caused indentations in the surface.
Karst topography (14) Distinctive topogra- phy formed in a region of chemically weath- ered limestone with poorly developed surface drainage and solution features that appear pitted and bumpy; originally named after the Krš Plateau in Slovenia.
Katabatic winds (6) Air drainage from el- evated regions, flowing as gravity winds. Lay- ers of air at the surface cool, become denser, and flow downslope; known worldwide by many local names.
Kettle (17) Forms when an isolated block of ice persists in a ground moraine, an outwash plain, or a valley floor after a glacier retreats; as the block finally melts, it leaves behind a steep- sided hole that frequently fills with water.
Kinetic energy (3) The energy of motion in a body; derived from the vibration of the body’s own movement and stated as temperature.
Lacustrine deposit (17) Lake sediments that form terraces, or benches, along former lake shorelines and often mark lake-level fluctua- tions over time.
Lagoon (16) An area of coastal seawater that is virtually cut off from the ocean by a bay barrier or barrier beach; also, the water sur- rounded and enclosed by an atoll.
Landfall (8) The location along a coast where a storm moves onshore.
Land and sea breezes (6) Wind along coast- lines and adjoining interior areas created by dif- ferent heating characteristics of land and water surfaces—onshore (landward) breeze in the af- ternoon and offshore (seaward) breeze at night.
Landslide (14) A sudden rapid downslope movement of a cohesive mass of regolith and/or bedrock in a variety of mass-movement forms under the influence of gravity; a form of mass movement.
Land–water heating differences (5) Differ- ences in the degree and way that land and water heat, as a result of contrasts in trans- mission, evaporation, mixing, and specific heat capacities. Land surfaces heat and cool faster than water and have continentality, whereas water provides a marine influence.
Large marine ecosystem (LME) (20) Distinc- tive oceanic regions identified for conservation purposes on the basis of organisms, ocean-floor topography, currents, areas of nutrient-rich upwelling circulation, or areas of significant predation, including human. The LME system is managed by the U.S. National Oceanic and Atmospheric Administration (NOAA).
Latent heat (7) Heat energy is stored in one of three states—ice, water, or water vapour. The energy is absorbed or released in each phase change from one state to another. Heat energy is absorbed as the latent heat of melting, vapourization, or evaporation. Heat energy is released as the latent heat of con- densation and freezing (or fusion).
Latent heat of condensation (7) The heat en- ergy released to the environment in a phase change from water vapour to liquid; under normal sea-level pressure, 540 calories are
released from each gram of water vapour that changes phase to water at boiling, and 585 calories are released from each gram of water vapour that condenses at 20°C.
Latent heat of sublimation (7) The heat en- ergy absorbed or released in the phase change from ice to water vapour or water vapour to ice—no liquid phase. The change from water vapour to ice is also called deposition.
Latent heat of vaporization (7) The heat energy absorbed from the environment in a phase change from liquid to water vapour at the boiling point; under normal sea-level pressure, 540 calories must be added to each gram of boiling water to achieve a phase change to water vapour.
Lateral moraine (17) Debris transported by a glacier that accumulates along the sides of the glacier and is deposited along these margins.
Laterization (18) A pedogenic process op- erating in well-drained soils that occurs in warm and humid regions; typical of Oxisols. Plentiful precipitation leaches soluble miner- als and soil constituents. Resulting soils usu- ally are reddish or yellowish.
Latitude (1) The angular distance measured north or south of the equator from a point at the center of Earth. A line connecting all points of the same latitudinal angle is a parallel. (Compare Longitude.)
Lava (12) Magma that issues from volcanic activity onto the surface; the extrusive rock that results when magma solidifies. (See Magma.)
Life zone (19) A zonation by altitude of plants and animals that form distinctive com- munities. Each life zone possesses its own temperature and precipitation relations.
Lightning (8) Flashes of light caused by tens of millions of volts of electrical charge heating the air to temperatures of 15 000°C to 30 000°C.
Limestone (12) The most common chemi- cal sedimentary rock (nonclastic); it is lith- ified calcium carbonate; very susceptible to chemical weathering by acids in the environ- ment, including carbonic acid in rainfall.
Limiting factor (19) The physical or chemi- cal factor that most inhibits biotic processes, through either lack or excess.
Lithification (12) The compaction, cemen- tation, and hardening of sediments into sedi- mentary rock.
Lithosphere (1, 12) Earth’s crust and that portion of the uppermost mantle directly below the crust, extending down about 70 km. Some sources use this term to refer to the entire Earth.
Littoral drift (16) Transport of sand, gravel, sediment, and debris along the shore; a more comprehensive term that considers beach drift and longshore drift combined.
Littoral zone (16) A specific coastal environ- ment; that region between the high-water line during a storm and a depth at which storm waves are unable to move sea-floor sediments.
Loam (18) A soil that is a mixture of sand, silt, and clay in almost equal proportions, with no one texture dominant; an ideal agri- cultural soil.
Location (1) A basic theme of geography dealing with the absolute and relative posi- tions of people, places, and things on Earth’s surface.
Loess (16) Large quantities of fine-grained clays and silts left as glacial outwash depos- its; subsequently blown by the wind great distances and redeposited as a generally un- stratified, homogeneous blanket of material
covering existing landscapes; in China, loess originated from desert lands.
Longitude (1) The angular distance mea- sured east or west of a prime meridian from a point at the center of Earth. A line connecting all points of the same longitude is a meridian. (Compare Latitude.)
Longshore current (16) A current that forms parallel to a beach as waves arrive at an angle to the shore; generated in the surf zone by wave action, transporting large amounts of sand and sediment. (See Beach drift.)
Luvisolic (18) A CSSC soil order with eluviation-illuviation processes that produce a light-coloured Ae horizon and a diagnos- tic Bt horizon. Soils of mixed deciduous– coniferous forests. Major occurrence is the St. Lawrence lowland. Luvisols do not have a solonetzic B horizon.
Magma (12) Molten rock from beneath Earth’s surface; fluid, gaseous, under tremen- dous pressure, and either intruded into exist- ing crustal rock or extruded onto the surface as lava. (See Lava.)
Magnetosphere (2) Earth’s magnetic force field, which is generated by dynamo-like motions within the planet’s outer core; de- flects the solar wind flow toward the upper atmosphere above each pole.
Mangrove swamp (16) A wetland ecosys- tem between 30° N and 30° S; tends to form a distinctive community of mangrove plants. (Compare Salt marsh.)
Mantle (12) An area within the planet rep- resenting about 80% of Earth’s total volume, with densities increasing with depth and averaging 45 g · cm−3; occurs between the core and the crust; is rich in iron and magnesium oxides and silicates.
Map (1, Appendix A) A generalized view of an area, usually some portion of Earth’s sur- face, as seen from above at a greatly reduced size. (See Scale, Map projection.)
Map projection (1, Appendix A) The reduc- tion of a spherical globe onto a flat surface in some orderly and systematic realignment of the latitude and longitude grid.
March Vernal equinox (2) See Vernal (March) equinox.
Marine effect (5) A quality of regions that are dominated by the moderating effect of the ocean and that exhibit a smaller range of minimum and maximum temperatures, both daily and annually, than do continental sta- tions. (See Continental effect, Land–water heating difference.)
Mass movement (14) All unit movements of materials propelled by gravity; can range from dry to wet, slow to fast, small to large, and free-falling to gradual or intermittent.
Mass wasting (14) Gravitational movement of nonunified material downslope; a specific form of mass movement.
Maunder Minimum (11) A solar minimum (a period with little sunspot activity and reduced solar irradiance) that lasted from about 1645 to 1715, corresponding with one of the coldest periods of the Little Ice Age. This relationship suggests a causal effect between decreased sun- spot numbers and cooling temperatures in the North Atlantic region. However, research has repeatedly refuted this hypothesis (for exam- ple, recent temperature warming corresponds with a prolonged solar minimum).
Meandering stream (15) The sinuous, curv- ing pattern common to graded streams, with the energetic outer portion of each curve subjected to the greatest erosive action and