Category: Dictionary

map : A picture of a place that is usually drawn to scale on a flat surface

mantle : A zone in the Earth’s interior between the crust and the core that is 2,900 kilometers (1,800 mi) thick. The lithosphere is composed of the topmost 65–70 kilometres (40–43 mi) of the mantle and the crust.

mammilated : Smooth and rounded in appearance, used of various landforms of different sizes from individual rocks to entire landscapes

makhtesh : A deep, closed valley (usually drained by a single wadi) surrounded by steep walls of resistant rock and superficially resembling a crater. The term is used primarily in the deserts of Israel and Egypt.

mainland : A term used to denote a contiguous landmass or political territory relative to its politically associated but geographically remote outlying territories. It is variously used to refer to the continental (i.e. non-insular) part of a polity relative to its exclaves or oceanic islands; or to the largest or most politically, economically, and/or demographically significant island within an island nation. For example, continental Europe is often considered “the mainland” relative to the British Isles, while the island of Great Britain is considered “the mainland” relative to Northern Ireland and the many smaller islands that constitute the United Kingdom.

main stem: Also called a trunk.

The primary downstream channel of a river as contrasted with its tributaries. Virtually all of the water in a river’s drainage basin eventually flows through the main stem.

magnetic north : The direction a compass points, towards the Magnetic North Pole. Magnetic north differs from true north and grid north.

magma : Molten rock containing liquids, crystals, and dissolved gases that forms within the upper part of the Earth’s mantle and crust. When erupted onto the Earth’s surface, it is called lava.

machair : A fertile, low-lying, grassy plain on the northwest coasts of Ireland and Scotland.

maar : A broad, shallow, flat-bottomed volcanic crater created by an eruption involving groundwater coming into contact with magma. Maars commonly have low rims and subtle relief and characteristically fill with water to form crater lakes.

lowland : Any area of land that is lower in elevation relative to another area. The term is often used as a conditional descriptor to distinguish related habitats or ecosystems, especially freshwater riparian areas, on the basis of elevation above sea level. Lowland areas are usually relatively flat and characterized by slow-flowing waterways and alluvial plains. Contrast upland.

longitude : A measure of distance east or west of the Prime Meridian, a line drawn between the North and South Poles and passing through the Royal Observatory at Greenwich, England.^[2] Lines of longitude, also called meridians, are the imaginary lines that cross the surface of the Earth in a north-south direction (parallel to the Prime Meridian) and measure how far east or west of the Prime Meridian a place is located.

loess : A soil made up of small particles that were transported by the wind to their present location

location theory : A group of theories which seek to explain the siting of economic activities in particular locations.

location : A particular point or place in physical space. Compare absolute location.

loam : A type of easily worked, highly fertile soil composed of clay, silt, and sand in an approximate ratio of 20:40:40. Loams generally heat rapidly, are well-aerated, and drain neither too quickly nor too slowly

lithospheric plates: Also called tectonic plates.

A series of rigid slabs (16 major ones at present) that make up the Earth’s outer shell. These plates float on top of a softer, more plastic layer in the Earth’s mantle

lithosphere : The Earth’s hard, outermost shell. It comprises the crust and the upper part of the mantle. It is divided into a mosaic of 16 major slabs or plates, which are known as lithospheric plates or tectonic plates

levee: Also called a dike, embankment, floodbank, or stopbank.

An elongated naturally occurring ridge or an artificially constructed wall or barrier which regulates water levels in areas prone to flooding. It is usually earthen and often parallel to the course of a river or a coastline.

LEDC : An acronym for Less Economically Developed Country.

legend : A key for understanding the meanings of the symbols or pictures on a map

leeward : Toward the lee side; sheltered from the wind; the direction downwind from a point of reference. Contrast windward.

lee : The side or slope of a physical feature (such as a hill or mountain) which faces downwind, i.e. away from the direction in which the wind is blowing, or which faces away from an advancing glacier or ice sheet. The lee side is often sheltered by the topography from exposure to the wind and any moisture it brings.

leaching : A process of soil nutrient removal through the erosive movement and chemical action of water.

lava : The term used for magma once it has erupted onto the Earth’s surface

latitude : A measure of distance north or south of the Equator. One degree of latitude equals approximately 110 kilometers (68 mi).^[2] Lines of latitude, also called circles of latitude or parallels, are the imaginary lines that cross the surface of the Earth in an east-west direction (parallel to the Equator) and measure how far north or south of the Equator a place is located.

lateral blast : A sideways-directed explosion from the side or summit of a volcano

landscape : 1.  A broad or distinct area of land consisting of a collection of landforms which define a general geomorphologic form or setting, e.g. a mountain range, valley, plain, coast, etc. Landforms within a landscape are spatially associated but may vary in formation processes and age.^[4]2.  The visible features of an area of land, its landforms, and how they integrate with natural or man-made features. In the broadest sense, landscapes may include geophysical landforms such as hills and mountains; bodies of water such as rivers, lakes, and the sea; living elements of land cover such as vegetation; human elements such as buildings, structures, and various forms of land use; and transitory elements such as lighting and weather conditions. They reflect both physical origins and the cultural overlay of human presence in a living synthesis of people and place.

landmass : Any large contiguous area of land typically surrounded by an ocean or sea. Compare continent.

landmark : Any natural or artificial feature that is recognizable enough to be used for navigation; a feature that stands out enough from its environment to be visible across long distances.

landform : A natural feature of the solid surface of the Earth. A combined set of landforms makes up the terrain of a given area, and their arrangement in a landscape is known as topography.

land cover : The physical material present on the surface of the Earth, including categories such as vegetation (grasslands, shrubs, forests, etc.), bare ground, water, asphalt and artificial surfaces, and many others.

land bridge : Any piece of land connecting larger land areas that are otherwise separated by water, especially one over which living organisms, such as terrestrial animals and plants, are able to cross and thereby colonize previously inaccessible lands. Land bridges may be created by falling sea levels, tectonic activity, or post-glacial rebound. Compare isthmus.

lake : A body of water localized in a basin and surrounded entirely by land. Lakes are often defined as separate from any river or stream that serves to feed or drain them.

lahar : See mudflow.

lagoon : A small area of water connected to the ocean but otherwise blockaded by one or more islands.

lacustrine plain : A nearly level land area formed by the infilling of a lake with sediment and the complete drainage or evaporation of water from the lake, leaving the deposited sediments behind

kolk : Also spelled colc.

1.  A violently rotating underwater vortex capable of plucking and scouring depressions in bedrock, which may leave behind distinct pits or lakes known as rock-cut basins or potholes.2.  Another name for a bog pond.

knoll : See hillock.

knob : A peak or projection from the top of a hill or mountain, or any rounded protrusion of land, especially a small but prominent or isolated hill with steep sides; a boulder or an area of resistant rock protruding from the side of a hill or mountain. The term is used primarily in the southern United States

knickpoint: Also called a nickpoint.

1.  A point of abrupt inflection in the longitudinal profile of a river or its channel or valley, such as occurs at a waterfall.2.  Any interruption or break in the character of a slope.

key : See cay.

kettle : Also called a kettle hole or pothole.

A shallow, sediment-filled body of water formed by blocks of ice calving from a retreating glacier, or by draining floodwaters.

karst : An area possessing surface topography resulting from the underground solution of subsurface limestone or dolomite

jungle : An area covered with dense vegetation dominated by large trees, often tropical.

jhum cultivation: Also called jhoom cultivation or slash-and-burn agriculture.

Clear-cutting and/or setting fire to an area of land so it can be used for farm cultivation.

jurisdiction : 1.  The right and power to apply the law in a particular place or within a defined field of responsibility. 2.  The geographical area to which such authority applies.

isthmus : A narrow piece of land connecting two larger land areas across an expanse of water by which they are otherwise separated.

isopleth : Any line on a map connecting places of equal value. These values may express physical or natural quantities, such as elevation above sea level (as with contour lines), or quantities related to social or economic statistics, such as population, wealth, or transport costs.

islet : A very small island.

island : Any piece of sub-continental land that is entirely surrounded by water.

Intracoastal Waterway (ICW) : A system of navigable inland waterway channels, maintained through dredging and sheltered for the most part by a series of linear offshore islands, that follows the Atlantic and Gulf Coasts of the United States more than 4,800 kilometres (3,000 mi) from Boston, Massachusetts, around the southern tip of Florida, to Brownsville, Texas

intervening opportunity : The existence of a closer, less expensive opportunity for obtaining a good or service, or for a migration destination. Such opportunities lessen the attractiveness of more distant places

International Date Line : A line of longitude generally 180 degrees east and west of the Prime Meridian. The date is one day earlier to the east of the line

intermediate directions : See intercardinal directions.

interfluve : A narrow, elongated, and plateau-like or ridge-like landform between two valleys, or an area of higher ground between two rivers in the same drainage basin.

intercardinal directions: Also called intermediate directions or ordinal directions.

The set of four intermediate directions used in cartography and navigation, each of which is located halfway between a pair of cardinal directions: northeast (NE), southeast (SE), southwest (SW), and northwest (NW). They are often included in the compass rose and are used to define further subdivisions such as the secondary-intercardinal directions.

: Also called integrative geography, environmental geography, or human–environment geography.

The branch of geography that describes and explains the spatial aspects of interactions between human individuals or societies and their natural environment.

integrated drainage : A drainage pattern in which stream systems have developed to the point that all parts of the landscape drain into some part of a stream and to a common base level, the initial or original surfaces having essentially eroded away entirely, such that few or no closed drainage systems are presen

insular : Of or relating to an island, or suggestive of the isolated condition of an island

inselberg: Also called a monadnock.

An isolated rocky hill, knob, ridge, or small mountain that rises abruptly from a virtually level surrounding plain. Compare mogote.

inlet : An indentation of a shoreline, usually long and narrow, which often leads to an enclosed body of salt water, such as a sound, bay, lagoon, or marsh.

Inertia Costs of Location : Costs borne by an activity because it remains located at its original site, even though the distributions of supply and demand have changed.

impoundment : 1.  Another name for a dam that impounds a body of water.

2.  The reservoir created by such a dam.

impact crater : A type of crater formed by the hypervelocity collision of a solid astronomical body, such as a meteor, with the Earth’s surface. Unlike volcanic craters, impact craters typically have raised rims higher in elevation and depressed floors lower in elevation than the surrounding terrain.

igneous rock : Rock formed when molten (melted) materials harden.

iceberg : A large chunk of fresh water ice which has broken away from a larger body of ice (such as a glacier or ice shelf) and is floating freely in open water.

ice shelf : A large floating platform of ice formed when a glacier or ice sheet in a coastal area flows onto the ocean surface. By contrast, sea ice is formed directly over the water and is typically much thinner.

ice sheet : Also called a continental glacier.

A mass of glacial ice that covers more than 50,000 square kilometres (19,000 sq mi) of land area; smaller masses of ice may be termed ice caps or ice shelves. The two polar ice sheets are the only ice sheets that currently exist on Earth.

ice cap : A flattened, often dome-shaped mass of ice that covers less than 50,000 square kilometres (19,000 sq mi) of land area and is not constrained by topographical features such as mountains; larger masses of ice are termed ice sheets. Contrast polar ice cap.

ice age : A time of widespread glaciation, such as the Pleistocene Epoch

hypsometry : The study or measurement of land elevation relative to mean sea level. Hypsometry is the terrestrial equivalent of bathymetry.

hypsography : The geographic representation on a map of features related to elevation, altitude, and other measures of height above a reference surface.

hydrosphere : The totality of the water found on, under, and above the Earth’s surface in liquid, solid, and gaseous forms, including all oceans, lakes, rivers, and streams, as well as all ice and glaciers and subsurface groundwater. Some definitions restrict the hydrosphere to liquid water only, instead placing solid forms in the cryosphere and gaseous forms in the atmosphere.

hydrography : The study of the surface waters of the Earth

humus : Partially decomposed organic soil material.

hummock : A small knoll or mound, typically less than 15 metres (49 ft) in height and situated above an otherwise level ground surface.

human geography : The branch of geography that studies humans and their communities, cultures, economies, and interactions with the environment by examining their relations with and across space and place. Along with physical geography, it is one of the two major sub-fields of geography.

hotspot : An area in the middle of a lithospheric plate where magma rises from the mantle and erupts at the Earth’s surface. Volcanoes sometimes occur above a hotspot.

horst : A raised block of the Earth’s crust, bounded by parallel escarpments or faults, that has been displaced upward or has remained stationary while adjacent blocks on either side, known as grabens, have been displaced downward. Horsts and grabens often occur side-by-side in a repeated series of vertical displacements.

horn : A mountain formed by the back-to-back abutment of three or four adjacent cirques, leaving a distinctly pyramidal peak.

horizon: Also called the skyline.

The apparent line that separates the ground from the sky, dividing all visible directions into two categories: those that intersect the Earth’s surface and those that do not. When not obscured by buildings, trees, or mountains, the true horizon can be useful in navigation and determining positional orientation.

hogback : Also hog’s back.

A long, narrow ridge or series of hills with a narrow crest and steep, symmetrical slopes of nearly equal inclination on both flanks, especially one created by the erosion of an outcropping which exposes homoclinal sedimentary rock strata.

historical geography : A branch of human geography that studies the ways in which geographic phenomena have changed over time, especially (though not necessarily limited to) geographic change as it relates to human activity.

hinterland : An area that is tributary to a place and linked to that place through lines of exchange or interaction.

hillock : Also called a knoll.

A small hill.

hill : Any landform that extends above the surrounding terrain. A hill is generally considered less steep than a mountain.

highway : Any major public or private road or other thoroughfare on land, especially one that is paved and capable of supporting high-capacity, rapid transit between populated places.

highland: Sometimes used interchangeably with upland.

1.  Any elevated region of land, often one that is mountainous or situated atop a plateau. The term is sometimes reserved for relatively low-elevation mountain ranges or foothills.2.  Any area of land (mountainous or otherwise) that is higher in elevation relative to another area. In this sense, the term is often used as a conditional descriptor to distinguish related habitats or ecosystems, especially freshwater riparian areas, on the basis of elevation above sea level.

hemisphere : Half of the Earth, usually conceived as resulting from the division of the globe into two equal parts of either north and south or east and west

hedgerow: Also simply called a hedge.

A line of closely spaced shrubs or trees, planted and trained so as to form a barrier, to mark the boundary between two neighboring areas, or to serve as a windbreak for crops in adjacent fields.

heath: Also called heathland.

A shrubland habitat found mainly on free-draining, infertile, acidic soils and characterized by open, low-growing, woody vegetation.

heartland : 1.  The central part of a region.2.  A part of a region considered essential to the viability and survival of the whole.

hearth : The source area of any innovation. The source area from which an idea, crop, artifact, or good is diffused to other areas.

headwall : A steep slope or sheer cliff face at the upper end of a valley (e.g. at the back of a cirque), or at the active face of a mine, pit, or quarry

headland : A high coastal promontory that extends out into a body of water, often surrounded by steep cliffs. A very large headland is often called a cape.

heading : The compass direction in which the bow or nose of a moving vessel or aircraft is pointed. This is not necessarily the same direction in which the vessel is actually traveling, known as its course; any difference between heading and course is due to the motion of the air or water through which the vessel is moving, or other aerodynamic effects such as skidding or slipping. See also bearing.

harmonic tremor : One of a series of continuous rhythmic earthquakes in the Earth’s upper lithosphere that can be detected by seismographs. Harmonic tremors often precede or accompany volcanic eruptions.

hanging valley : A tributary valley that is higher in elevation than the main valley into which it drains, such that it appears to be “hanging” above the lower valley. Hanging valleys are commonly the result of differential glacial erosion, when adjacent areas beneath a glacier are subjected to different rates of erosion.