Oasis: A fertile area in a desert or arid land, formed due to water being present in that particular area, is known as an Oasis.
Obsequent Stream: A stream that flows in a direction opposite to the original slope of the land in the area is called an obsequent stream.
Occluded front A front that is formed as a cold front overtakes a warm front and lifts the warm air completely off the ground.
Occlusion: As per geographical definitions, occlusion is an atmospheric phenomenon in which a mass of cold air surrounds a mass of warm air and forces it to move upwards. If the air surrounding the mass of warm is cooler than the cold air ahead of the warm air, it is called a cold occlusion and if the air surrounding the mass of warm is warmer than the cold air ahead of the warm air it is called a warm occlusion.
Occupational Structure: the balance between the different sectors of a country's workforce e.g. primary, secondary, tertiary, quaternary.
Ocean Basin: The part of the earth's lithosphere that is taken up by the oceans comprising the ocean crust is known as the ocean basin.
Ocean Current: An ocean current is the flow of surface ocean water in a definable direction.
Ocean Trench: An ocean trench is a deep, long, and narrow depression on the ocean floor formed due to the sliding of an ocean plate beneath another.
Ocean: The salt water surrounding the great land masses, and divided by the land masses into several distinct portions, each of which is called an ocean.
Oceanic Crust: The earth's crust that is found on the ocean floor in the form of a thick mass of igneous rocks is called the oceanic crust.
Oceanic Plate: A part of the earth's crust that is found below sea-level and consists mainly of sima is known as the oceanic plate.
Offshore: In geographical terms, offshore can be defined as the moving away of wind from the shore or land towards the sea.
Off-shore: out at sea, away from the land.
Oil refinery (= olieraffinaderij)
Okta A measure of cloud cover (in fractions of eight) on a synoptic chart.
Omnivore: Omnivore, in geographical terminology, refers to people or animals who feed on both, plants as well as meat.
Onion Weathering: see Exfoliation.
Onshore: In geographical terms, onshore can be defined as the moving of wind away from the sea towards the shore or land.
Oolith: Ooliths are tiny grains that are spherical in shape, obtained from sedimentary rocks from sea waters, composed of concentric layers of calcium carbonate.
Oolitic Limestone: An oolitic limestone is a type of even textured limestone that comprises ooliths and skeletons of calcareous animals.
Open range: A cattle- or sheep-ranching area characterized by a general absence of fences.
Open-Cast Mine: a large quarry where a large pit is excavated on the Earth's surface to remove rock.
Opencast Mining: Opencast mining is the extraction or mining of ores and minerals found close to the surface of the earth, by removing the material lying above and breaking the ore.
Ordnance Survey: The official government organisation for producing maps of the UK.
Ore: a rock containing minerals useful to people, e.g. iron ore, gold ore.
Organic Farming: It is defined as an agricultural process of producing foods naturally without the use of synthetic pesticides and fertilizers. Instead, compost, green manure, and environmental friendly methods like crop rotation and mechanical cultivation are used for organic food production.
Organic Farming: this avoids the use of inorganic chemical fertilisers, pesticides and herbicides.
Orogenesis: Orogenesis, in the geography terms list, is defined as the process through which mountains are formed by the folding and faulting of the earth's crust. Learn more on how are mountains formed.
Orographic rainfall: Precipitation that results when moist air is lifted over a topographic barrier such as a mountain range.
Orographic: In geography, orographic refers to anything that is related to mountains or related to the study of mountains.
Out-of-town Shopping Centre: a large group of shops built either on a site on the edge of the urban area or on the site of a former large industrial area. Such centres usually have large carparks, a pedestrianised, air-conditioned environment and over 100 shops.
Outputs: products from a factory system, which include pollution and waste.
Outputs: the result of the farmer's work, e.g. crops, livestock, animal waste.
Outwash Plain: In geographical glossary, outwash plain is defined as a flat, sloping surface that comprises gravel and rock debris, deposited by a network of glacial streams.
Outwash: Rocky and sandy surface material deposited by meltwater that flowed from a glacier.
Overburden: Material covering a mineral seam or bed that must be removed before the mineral can be removed in strip mining.
Over-Cropping: see over-cultivation.
Over-Cultivation: the excessive use of farmland to the point where productivity falls due to soil exhaustion or land degradation.
Overgrazing: the destruction of the protective vegetation cover by having too many animals grazing upon it.
Overgrazing: The overfeeding of animals on vegetation cover that leads to the damage of the land, is known as overgrazing.
Overheads: costs which do not vary with output; these costs include rent, wages, electricity, etc.
Overland Flow: Overland flow occurs when the water flowing on the land surface flows into a body of water due to over saturation of the land that it flows on or due to rainfall exceeding infiltration.
Overpopulation: where there are too many people and not enough resources to support a satisfactory quality of life.
Over-Production: where too much food is produced as a result of EU policies to ensure that Europe is self- sufficient in food; this results in very expensive storage. (See CAP, Grain Mountains, Milk Lakes, Surplus, Set-aside, Diversification, Quotas, Guaranteed Prices, Subsidies, Intervention).
Overseas Competition: NICs have the advantage of cheap labour, expanding national markets and the newest technology. This has led to a global shift of manufacturing industry towards South-East Asia.
Overspill Town: a town that expanded by taking people who were forced to move out of cities as a result of slum clearance and redevelopment schemes.
Over-urbanisation: problems experienced by most LEDC cities e.g. Bombay, where too many people are migrating to the city resulting in housing shortages, poor housing conditions, lack of sanitation and piped water, illness and crime, traffic congestion, pollution, over-stretched services, unemployment, underemployment, etc..
Owner-occupied: a house lived in by its owner (as opposed to renting - see tenant).
Ox-bow Lake: An Ox-bow lake is a crescent-shaped lake that is formed when one of its meanders are cut-off or isolated.
Ox-bow Lake: a meander which has been cut off from the main river channel and abandoned.
Ozone Layer: A region of the earth's stratosphere that contains a high concentration of ozone, which is responsible for absorbing the harmful ultraviolet radiation of the sun, is called the ozone layer. Read more on ozone layer depletion.