Library: Geology by Credo Reference: Geographic Formations

Natural Phenomena

Earthquake: Topic Page
Trembling or shaking movement of the earth's surface.
Erosion: Topic Page
General term for the processes by which the surface of the earth is constantly being worn away.
Flood: Topic Page
An inundation of land by the rise and overflow of a body of water. Floods occur most commonly when water from heavy rainfall, from melting ice and snow, or from a combination of these exceeds the carrying capacity of the river system, lake, or the like into which it runs.
Glacial Erosion: Topic Page
Wearing-down and removal of rocks and soil by a glacier. Glacial erosion forms impressive landscape features, including glacial troughs (U-shaped valleys), arêtes (steep ridges), corries (enlarged hollows), and pyramidal peaks (high mountain peaks with three or more arêtes).
Greenhouse Effect: Topic Page
The warming of the Earth’s surface as a result of the trapping of long-wave radiation by carbon dioxide, ozone, and certain other gases in the Earth’s atmosphere.
Hurricane: Topic Page
Tropical cyclone in which winds attain speeds greater than 74 mi (119 km) per hr.
Landslide: Topic Page
The rapid slipping of a mass of earth or rock from a higher elevation to a lower level under the influence of gravity and water lubrication.
Rain: Topic Page
Precipitation in liquid form. It consists of drops of water falling from clouds; if the drops are very small, they are collectively termed drizzle.
Snow: Topic Page
Precipitation formed by the sublimation of water vapor into solid crystals at temperatures below freezing.
Tide: Topic Page
Alternate and regular rise and fall of sea level in oceans and other large bodies of water. These changes are caused by the gravitational attraction of the moon and, to a lesser extent, of the sun on the earth.
Tornado: Topic Page
A violently destructive storm characterized by a funnel-shaped rotating column of air which can be seen extending downward from thunder clouds to the ground, tracing a narrow path across the land.
Tsunami: Topic Page
Series of catastrophic ocean waves generated by submarine movements, which may be caused by earthquakes, volcanic eruptions, landslides beneath the ocean, or an asteroid striking the earth. Tsunamis are also called seismic sea waves or, popularly, tidal waves.
Volcano: Topic Page
Vents or fissures in the earth's crust through which gases, molten rock, or lava, and solid fragments are discharged.
Wind: Topic Page
Flow of air relative to the earth's surface. A wind is named according to the point of the compass from which it blows, e.g., a wind blowing from the north is a north wind.

Glacial Features

Glacier: Topic Page
Moving mass of ice that survives year to year, formed by the compacting of snow into névé and then into granular ice and set in motion outward and downward by the force of gravity and the stress of its accumulated mass. Glaciers are usually found in high altitudes and latitudes.
Cirques: Topic Page
Cirques are glacially eroded features characteristic of mountain glaciation, and are also known as corries or cwms.
Drumlin: Topic Page
A drumlin is a subglacial landform that appears as a distinctive streamlined hill of sediment in the postglacial landscape. The term is derived from a Gaelic word meaning a mound or rounded hill.
Eskers: Topic Page
Eskers are ridges of glaciofluvial sediment deposited in ice-walled channels or subglacial tunnels.
Glacial Erratic
In The Dictionary of Physical Geography
A rock or boulder that has been carried to its present location by the action of a glacier. I
Hanging Valley: Topic Page
A tributary valley whose floor is discordant with the floor of the main valley. Hanging valleys are a hallmark of glacial erosion in mountains.
Kames: Topic Page
A kame is an ice contact glaciofluvial landform. It is composed of sediment deposited by water in contact with glacier ice either at the side of, or on the surface of a glacier.
Moraines: Topic Page
A moraine is a glacial landform created by the deposition or deformation of sediment by glacier ice.

Water Formations

Alluvial Fans: Topic Page
A fan-shaped, low-angle depositional landform of predominantly fluvial origin, characterised by a distributary pattern of channels, and composed of alluvial deposits.
Beach: Topic Page
Strip of land bordering the sea, normally consisting of boulders and pebbles on exposed coasts, or sand on sheltered coasts.
Delta: Topic Page
River sediments deposited when a river flows into a standing body of water with no strong currents, such as a lake, lagoon, sea, or ocean.
Floodplains: Topic Page
A floodplain is one of the ubiquitous fluvial features found along major rivers. It is a wide, flat plain of alluvium on either side of a river extending to the base of a valley that is seasonally inundated.
Lake: Topic Page
A large area of still fresh or salt water, surrounded by land and lying in a depression in the Earth’s surface, which receives water from rivers, streams, springs, etc.
Ocean: Topic Page
Interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean.
River: Topic Page

Large body of water that flows down a slope along a channel restricted by adjacent banks and levees. A river starts at a point called its source, and enters a sea or lake at its mouth.
Waterfalls: Topic Page
A stream that falls from a height. Waterfalls are often the sites of greatest concentration of energy dissipation along the course of a stream and have generally been regarded as forming where a soft rock is eroded from beneath a harder rock (the caprock model).

Land Formations

Caldera: Topic Page
Calderas are volcanic depressions, roughly circular in surface plan, with a diameter greater than depth, and representing roof collapse into shallow underlying magma reservoirs.
Continent: Topic Page
Largest unit of landmasses on the earth. The continents include Eurasia (conventionally regarded as two continents, Europe and Asia), Africa, North America, South America, Australia, and Antarctica.
Cuestas: Topic Page
An asymmetric ridge characterized by a short, steep escarpment on one side, and a long, gentle slope on the other. The steep side exposes the edge of erosion-resistant rock layers that form the cuestas.
Desert: Topic Page
Arid region, usually partly covered by sand, having scanty vegetation or sometimes almost none, and capable of supporting only a limited and specially adapted animal population.
Hogbacks: Topic Page
A sharp-crested ridge with steep slopes on both sides, formed by the erosion of steeply tilted rock layers. Hogbacks are commonly formed along the eroded flanks of large, tightly folded anticlines and synclines
Island: Topic Page
A piece of land, smaller than a continent, which is completely surrounded by water, eg Britain, Cyprus, Greenland, etc.
Mountain: Topic Page
High land mass projecting conspicuously above its surroundings and usually of limited width at its summit.
Nunatak: Topic Page
A nunatak is an upland surface that protrudes above the surface of an ice sheet, ice cap, or ice field. The term nunatak derives from the Inuit language and was initially used by Greenlanders to refer to the mountains that protruded above the surface of the Greenland Ice Sheet.
Pingos: Topic Page
Pingos are ice-cored hills, typically conical in shape, covered by soil and vegetation with a core of massive ice produced primarily by the injection of water to the base of aggrading permafrost.
Tor: Topic Page
An exposure of bedrock rising above its surroundings and formed by (1) subaerial weathering causing spheroidal modification to the form of outcrops; (2) differential weathering and removal of weathered debris by mass wasting and stripping; (3) slope retreat of larger inselbergs or (4) frost weathering in periglacial conditions followed by solifluction.
Volcano: Topic Page
Any of various vents in the Earth’s crust through which magma is or has previously been forced out onto the surface, forming various structures but usually taking the form of a conical hill due to the build up of solidified lava.
Yardang: Topic Page
Streamlined and parallel hills, knobs or ridges of rock (or other consolidated material), often with steep or undercut sides. Some remarkable examples exhibit parallelism for many tens of kilometres.