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right Tower Fall in Yellowstone National Park
A waterfall is usually a geological formation resulting from water, often in the form of a stream flowing over an erosion-resistant rock formation that forms a sudden break in elevation. Waterfalls may also be artificial, and they are sometimes used for garden and landscape ornament.
Some waterfalls form in montane environments where erosion is rapid and stream courses may be subject to sudden and catastrophic change. In such cases, the waterfall may not be the end product of many years of water action over a region, but rather the result of relatively sudden geological processes such as thrust faults or volcanic action.
Most waterfalls are the result of many years of action of water on the underlying strata. Typically, a stream will flow across an area of formations, and more resistant rock strata will form shelves across the streamway, elevated above the further stream bed when the less erosion-resistant rock around it disappears. Over a period of years, the edges of this shelf will gradually break away and the waterfall will steadily move upstream. Often, the rock strata just below the more resistant shelf will be of a softer type, and will erode out to form a shallow cave-like formation known as a rock shelter (also known as a rock house) under and behind the waterfall.
Streams often become wider and more shallow just above waterfalls due to flowing over the rock shelf, and there is usually a deep pool just below the waterfall due to the kinetic energy of the water hitting the bottom.
Waterfalls are a hindrance to river transportation. For instance the Welland Canal was built in 1829 to allow ships to pass Niagara Falls in the Great Lakes.
1 Types of waterfalls
Certain terms describe several common types of waterfalls:
- Block, where the water descends from a relatively wide stream or river;
- Cascade, where the water descends a series of rock steps;
- Fan, where the water spreads horizontally as it descends while remaining in contact with bedrock;
- Horsetail, where descending water maintains some contact with bedrock;
- Plunge, where the water descends vertically, losing contact with the bedrock surface;
- Punchbowl, where the water descends in a constricted form, then spreads out in a wider pool;
- Segmented, where distinctly separate flows of water form as it descends; and
- Tiered, where water drops in a series of distinct steps or falls.
2 Examples of large waterfalls
A partial list of waterfallsList of waterfalls Africa Burkina Faso Tagbaladougou Falls Democratic Republic of the Congo Boyoma Falls (Stanley Falls) Lofoi Falls Central African Republic Matakil Falls Chad Gauthiot Falls Ethiopia Blue Nile Falls Guinea Tinkisso Falls Lesotho Maletsun is available; the world's largest waterfalls include:
- South America's Angel FallsAngel Falls or Salto Angel is the world's highest free-falling waterfall at 978 metres (3,212 feet) with an uninterrupted drop of 807 metres (2,647 feet). It is located on an unnamed tributary of the Rio Caroni in Venezuela. Although first sighted in the, the world's highest at 979 m (3230 ft), in VenezuelaThe Bolivarian Republic of Venezuela (Spanish: Republica Bolivariana de Venezuela "Bolivarian Republic of Venezuela") is a country in northern South America. 1 It borders the Caribbean Sea and the Atlantic Ocean to the north, Guyana to the east, Brazil to ;
- Africa's Victoria FallsVictoria Falls, by Michael W. Carroll, original in Victoria Falls or Mosi-oa-Tunya as it is also known locally, is the world's largest waterfall and is considered by many one of the world's seven natural wonders. 6 km wide with a maximum drop of 128 m (42, the world's largest, on the Zambezi River;
- Africa's Boyoma FallsBoyoma Falls formerly known as Stanley Falls consists of seven cataracts extending over 100 km on the Lualaba River near Kisangani (formerly Stanleyville) in the Democratic Republic of the Congo. At the bottom of the falls the Lualaba becomes the Congo., with the world's highest volume, 17,000 m³/s (600,000 ft³/s), on the Congo RiverThe Congo is the largest river in Western Central Africa. Its overall length of 4,380 km (2,720 mi) makes it the second longest in Africa (after the Nile). If the Chambeshi River is taken as the source, the overall length increases to 4,670 km (2900 mi).;
- Yosemite FallsYosemite Falls is the highest waterfall in North America. Located in Yosemite National Park in the Sierra Nevada mountains of California, it is a breathtaking sight best viewed in the late spring. The total 2425 foot distance from the top of the upper fal, the tallest in North America, located in Yosemite National Park; and
- Rhine Falls, Europe's largest, located in Switzerland.
