Blind Valley : A valley in limestone country, dry or with a stream, which ends in a steep wall into the base of which the surface flow of water disappears under ground.

Bog : An area of soft, wet, spongy ground consisting mainly of decayed or decaying mass and other vegetable matter.

Bora : A cold and often dry wind experienced along the eastern coast of the Adriatic sea.

Bore : A high tidal wave causing back flow of water in a river.

Caatinga : Thorn-Forest of Brazil.

Canyon : A Narrow, Deep, Steep-Sided River Valley Cut In The Soft Rocks.

Cape : A headland, a more or less pointed piece of land jutting out into the sea.

Chaparral : The evergreen, Sclero-phyllous vegetation[1] of the lower flanks of the Coastal and Santa Lucia ranges of southern California.  It is usually known as coastal chaparral and has strong similarities with Maquis.

Cartography : The art of drawing maps and charts

Celestial Equator : The imaginary circle formed by the intersection of a plane through the centre of the earth perpendicular to its axis and the celestial sphere.

Celestial Sphere : A sphere of infinite radius having its centre at some point in the solar system, for example, at the centre of the earth, on to which all members of the solar system may be projected.

Cirque : A step-walled amphitheatre, or basin of glacial origin at the head of a mountain valley (in some cases containing a small lake), resulting from frost and glacial action (base erosion and back cutting).  At the meeting of two cirques knife edge or Arête is formed.

Clinometer/Inclinometer : An instrument used for determining the difference in elevation between two points or the slope between two points.          

Coniferous : Cone-bearing plants with needle-shaped leaves.

Connate Water : Water entrapped in the interstices of rocks during their formation, also called fossil water.

Coral : A kind of rock formed of polyps forming reefs in the oceans.

Colour of the sky : Seems blue because of the selective scattering of light in the atmosphere by gases and dust particles.

Cold Front : The boundary between a warm air mass, which is being undercut by an advancing cold air mass. This usually occurs at the rear of the warm sector in a depression.

Cainozoic (Cenozoic, Kainozoic) : A greek term meaning ‘recent life’ adapted to describe the third of the eras of geological time.  Originally, the term was regarded as being synonymous with the tertiary, i.e. succeeding the mesozoic and finishing at the quaternary.

Chelation : The process by which rocks and soils decompose or disintegrate through the action of organisms or organic substances.

Cheluviation : A term derived from the combination of chelation and eluviation, whereby water containing organic extracts combines with metallic cations in the soil to form a chelate.  The sesquioxide-rich solution then moves downward, through the soil profile (hence eluviation) and moves the aluminium and iron into the lower horizons.

Chemical Weathering : The processes, which lead to the decomposition or break-down of solid rocks by means of chemical reactions.  these comprise carbonation, hydrolysis, oxidation, reduction and solution.

Cloud-Seeding : A term used in the experimental procedure of artificial rain-making.  It is based on the principles out-lined in the Bergeron Findeisen theory of precipitation in which clouds containing super cooled water droplets are ‘seeded’ artificially with freezing nuclei, such as silver iodide or dry ice, thus promoting the growth of ice crystals alongside super- cooled droplets and encouraging vapour fluxes/precipitation.

Continental Drift : A Concept, Initiated In 1858 By A. Snider but developed and popularized by F.B.Taylor (1908) and A. Wegener (1915), which suggested that continents can move around the Earth’s surface because of the weakness of the suboceanic crust.  Although it was originally based on the apparent ‘jig-saw’ fit of the opposing coasts of the Atlantic Ocean, much evidence of matching fossils, geological structures, etc. was accumulated to support the former movements, although no adequate mechanism were advocated. It was suggested by Wegener that the world’s continents had been derived from the breakup of the two super continents of Gondwanaland and Laurasia, which had themselves been united as Pangaea in pre Mesozoic times.  The entire concept has been replaced by the more sophisticated hypothesis of plate tectonics.

Deciduous Forest : Consists of trees that shed their leaves in the dry season.

Downs : Grasslands of Australia.

Denudation : Wearing away of rocks by various agencies like wind, water and glaciers.

Desiccation : A progressive increase of aridity, often as a result of climatic change.  It may be due to natural changes such as a decrease in precipitation or an interference with a river regime or it may result from human interference-over-grazing, deforestation, irrigation failure, etc. It is generally accompanied by a falling water table, a drying-out of the soil and a deterioration in the quality and amount of the vegetation cover.

Desillication : (1) The removal of silica from a soil, generally by leaching of the surface material in regions of heavy rain-fall. (2) The term is also used to denote the removal of silica either from rocks by chemical weathering in hot fumed climates or from a magma by reaction with the country rock (e.g. in limestone this would form lime silicates).

Eluviation : Removal of material in solution or suspension from the upper horizons of the soils to the lower.

Estuary : Mouth of a river where tidal effects are evident and where fresh water and sea water mix.  The term also refers to river valleys which have been flooded by sea due to coastal subsidence.

Evapotranspiration : The term signifies total loss of water (moisture) from soil in the form of water vapour, including that loss by evaporation from open water bodies, the surface of rocks, and also that loss by transpiration from growing plants.

El Nino : A name given to the occasional development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peru current (Humboldt current) which, normally operates. El Nino is an extension of the Equatorial current and leads to an increase in surface-water temperatures of Peruvian coast and a decrease in plankton which thrive in the colder current.  As a result of this reduction in their food supply the fish population is seriously depleted.  It recurs every seven to fourteen years and results from a weakening of the SE Trades in the Pacific.  

Euphotic Zone : The surface layer of any body of water through which light can penetrate, thereby leading to photosynthesis.

Fathometer : Instrument used for measuring the depth of the ocean.

Fiord :  A glacial valley or part there of now under the sea.

Fluvial : Belonging or relating to a river.

Fog : A dense mass of small water drops or smoke or dust particles in the lower layers of the atmosphere.

Gorge : A narrow and deep valley of a river.

Greenwich Meridian : The Standard Meridian through which the 0⁰ line of longitude runs and from which degrees of longitude E or W are calculated.  It is measured from the old Royal Observatory at Greenwich, England.  Other prime meridians in France and USA have never been universally accepted.

Halophyte : A plant, which grows naturally in saline environment

Hinterland :  Area from which a port gets most of its exports and serves through imports.

Hyetograph : A chart showing the distribution of rainfall of a particular area, usually throughout a year.

Hygrophyte : Plant growing in very wet areas

Horst : A fault-defined block, which has been left upstanding by the sinking of the adjoining land along normal faults or has been uplifted along parallel faults.  Although it coincides with prominent relief form at its inception, the topography may be denuded to leave only the structural formation.

Hurricane : A name of Spanish derivation which refers primarily to the revolving tropical storms of the Caribbean and gulf of Mexico.

Hydration : One of the major processes of mechanical weathering, involving the addition of water to a mineral, causing it to expand and thereby initiate stress within the rock.

Insolation : Radiant energy received from the sun by the earth.

Intertropical Convergence Zone Or Intertropical Front : Zone of low atmospheric pressure near the equator where the northeast and southeast trade winds converge.

Inversion of Temperature : Strictly, inversion of temperature gradient.  Normally air temperature decreases with increasing elevation but under certain weather conditions the converse may be true.  Thus, contrary to the normal environmental lapse-rate, over a limited height range, air temperature increases with height so that a layer of warmer air overlies a colder layer.

Karst Region or Karstland : Lime-Stone region in which most of the drainage is underground, the surface being dry and barren. Named after the Karst region of erstwhile Yugoslavia.

Lagoon : Part of sea partially cut off from it by deposits of sand (called bars) or coral reefs, for example Chilka Lake in Odisha.

Lapse Rate : The rate of change of temperature in atmosphere with height; it is said to be positive when temperature decreases with height, as it normally does, and negative when temperature increases with height, as in temperature inversion.

Light Year : Distance traveled by light in one year, the speed being, 300000 kilometres per second.  The unit is used for measuring the distance of stars from the earth. One light year = 9.4605284 × 10¹⁵ meters

Lithosphere : The solid crust of the earth.

Loess :  A deposit of fine silt or dust generally held to have been transported to its present situation by wind.

Lunar Month : The interval of time in which the moon makes one complete revolution around the earth i.e. about 29.5 days.

Magnetic Storms : Large, irregular variations or disturbances of the earth’s magnetic field.

Meridian : A line of longitude, or half of one of the great circle that pass through the poles and cut the equator at right angles.

Mesophyte : A plant that requires an average amount of moisture.  Most common trees and shrubs and mesophytes.

Mestizo : Offspring of a european and an american indian-the term is used mostly in South America.

Midnight Sun :  A phenomenon observed in high latitudes around midsummer when the sun does not sink below the horizon throughout the 24 hours of a day and night cycle and may thus is visible even at midnight.

Moraine : The debris of fragments of rock material brought down with the movement of glacier.

Nivation : Erosion due to action of snow.

Opisometer :  Instrument used for measuring distances on a map.

Orographic Rain : Rain caused by mountains standing in the path of moisture-laden winds.

Outwash Plain : Alluvial Plain formed by streams originating from the melting ice of a glacier.

Pampas : The mid-latitude grasslands of South America.

Pelagic : Belonging To the Open Sea

Syzygy : When the Sun, the moon and the Earth are in the same line, either in conjunction or opposition.

Quadrature : A situation when the Sun, the Earth and the Moon (or another planet) are at ‘right-angles’, with the Earth as the apex, which occurs in the case of the Moon twice each month.  The tide-producing gravitational effects of the Sun and the Moon are then in opposition, and thus the range of the tides is reduced; these are NEAP TIDES, with low high tides and high low tides.

Peninsula : A stretch of land almost surrounded by water on three sides.

Perigee : The point in the orbit of moon or a planet or in the apparent orbit of the sun, nearest to the earth.

Permafrost : Ground that is permanently frozen.

Piedmont : Belonging to or related to the foot of a mountain.

Planimeter : Instrument for measuring irregular plane areas on maps.

Prairies : Mid-Latitude grasslands of North America.

Pressure Gradient : Rate at which pressure changes horizontally on the earth’s surface.

Radiation : Process by which a body emits radiant energy, for example, in the form of heat.

Rain Shadow : Area having relatively lower average rainfall because it is sheltered from the prevailing rain-bearing winds by a range of mountains or hills.

Reef : Ridge of rocks lying near the surface of the sea, which may be visible at low tide, but usually covered by water.

Reg : A sandy desert is called a reg.

Rhumb Line of Loxodrome : Line on the earth’s surface, which cuts all meridians at the same angle.

Radiocarbon Dating : A method of determining the age of an organic material by measuring the proportion of the C-14 isotope contained within its carbon content.  This radioactive carbon isotope enters the Earth’s living organisms from the atmosphere, continuing to be assimilated until the organism dies or is buried beneath sediments, at which point radioactive decay begins.  The half-life of C-14 is 5570 years, a relatively short half-life.

Relative Humidity : An index of the amount of water vapour present in the atmosphere.  It is the actual vapour pressure expressed as a percentage of the saturation vapour pressure which would be possible at the same air temperature.  Relative humidity is an attempt to measure the readiness with which vapour will condense from the air, and is concerned with two variables the actual water vapour in a given mass of atmosphere and the temperature of that mass of air, since this determines the capacity of the air to hold the water vapour.  The value of relative humidity varies inversely with temperature and therefore usually rises during the night, because temperature falls, even though the amount of water vapour may remain constant.  It is measured by a hygrometer.

Saprophyte : A plant, which lives on decaying organic matter.  Most such plants are fungi.

Savanna :  An area of tropical grassland with scattered trees.

Selvas : Dense equatorial forests of the Amazon Basin in South America.

Sidereal Day : The period of time during which a star describes a complete circle in its apparent journey around the pole star, representing the period of one rotation of the earth on its axis and equal to 23 hours 56 minutes 4 seconds.  It is thus about 4 minutes shorter than mean solar day.

Sleet : Precipitation consisting of a mixture of snow and rain.

Smog : Fog heavily laden with smoke.

Snow-Line : Lower limit of perpetual snow-the snow above this line does not melt completely even in summer.

Soil Erosion : The wearing away and loss of soil mainly by the action of wind and water.

Solar Constant : Intensity of the sun’s radiation in space at the mean distance of the earth from the sun.

Solar Day, Mean : The average period taken by the earth in making one rotation on its axis in relation to the sun-24 hours.

Solstice : The time during summer or winter when the sun is vertically about the point which represents its farthest distance north or south of the equator-the two tropics.

Steppe : Mid-Latitude Grasslands of Eurasia

Strait : Narrow stretch of sea connecting two extensive areas of sea.

Sublimation : Change of state of water from solid to vapour directly or vice versa.

Taiga : Coniferous Forestland of Siberia and Canada and Europe.

Territorial Waters :  Any area of sea over which an adjacent country claims jurisdiction.  The range is decided to be 12 nautical miles from coast as per UN convention on laws of sea.

Tidal Range : Average difference in water level between high and low tide at one place.

Topographic Map : Map on sufficiently large scale to show the detailed surface features of an area.

Trans-Humance : Practice among pastoral communities to move their animals seasonally between two regions of different climate.

Tributary : Smaller river which joins a larger river.

Tropics : The Tropic Of Cancer and the Tropic Of Capricorn located at 23 ½ N and S, respectively, are the northward and southward limits up to which the sun’s vertical rays can reach.  The area bounded by the two tropics is called the tropical zone.

Tropophyte : A plant, which acts as a hygrophyte in one season and a xerophyte in the other.

Terra Rossa : A reddish clay-loam soil developed under a warm seasonally dry climate, on limestone, especially in the karst terrain of Yugoslavia.  It Is Rich In Iron Sesquioxides and has a low base status.  Although it is thought to be a residual soil there is no agreement on its exact origin, but since it appears typically under garrigue vegetation in the Mediterranean region it may possibly result from deforestation.  The general lack of humus in the terra rossa would support such a possibility.  It is related to the red soils, rendzina.

Typhoon : A small but intense low-pressure system of the w. pacific and the china sea, which produces violent winds and heavy rain (Tropical Cyclone).  Its wind speeds exceed force 12 on the Beaufort scale.

Van Allen’s Radiation Belts : Named after the physicist who discovered them, these are two bands of the outermost layer of the atmosphere (Magnetosphere), At Heights Of 3000 Km And 16000 Km Above The Earth’s Surface. Here The Ionized Particles trapped by the earth’s magnetic field from the solar radiation, concentrate.

Volcano : Vent in the earth’s crust caused by magma forcing its way to the surface through which flow molten or solid rock from the interior of the earth.

Watershed : Elevated boundary line separating headstreams, which are tributaries to different river systems or basins.

Weathering : Decay and disintegration of rocks of the earth’s crust by exposure to the atmosphere, it is one of the main processes of denudation.

Warm Front : The boundary between an advancing warm air mass, which is over-riding a cold air mass.  This usually occurs at the front of the warm sector in a depression.  The gradient of a warm front is less steep than that of a cold front.  This gradual upward movement of moist warm air along the warm front results in the condensation of water vapour and the formation of cloud.

Wind Vane : Instrument used to indicate t he direction of the wind.

Xerophyte : Plant, which is adapted to living in a region where little moisture is available.

Zenith : Point in the celestial sphere vertically above one’s head.

Zodiac : Zone of the heavens in which lie the paths of the sun, the moon, and the chief planets.

Oxbow Lakes : Oxbow lakes are formed by a meandering river across its flood plain.  Such a river often cuts off a meander at its neck and closes it off by a deposition of silt and sediment.  This happens especially during a flood when it abandons a meander and beings to flow in straight course.  The abandoned meander forms the oxbow lake.  Such a lake is crescent-shaped and its general outline is longish.  Narrow in width, these lakes are deeper towards the convex bank.

Marginal Sea : MARGINAL SEA is a semi-enclosed sea that borders a continent, and lies on a submerged portion of a continental mass, rather than within an ocean basin; for example: Sea of Okhotsk, Sea of Japan, Yellow Sea, Celebes Sea, Baltic Sea, North Sea, Red Sea, Persian Gulf.

Continental Sea  : A partially enclosed sea, lying on or within a continent in the structural sense, linked with the open ocean, for example Baltic Sea, Hudson Bay, Yellow Sea, Mediterranean Sea.

Artesian Well : A boring put down into an aquifer in an Artesian Basin is called ‘ARTESIAN WELL’. If the outlet of Artesian Well in the center of the basin is at a lower level than the Water-Table within the aquifer around the edge of the basin, water will rise in the well under hydrostatic pressure. It is named from wells of this type in regions in NE France.  The term is also loosely applied to any well in which water rises some distance under pressure, though not to the surface, sometimes call ‘SUB-ARTESIAN’.