jaskinie: Waterfall

Evidence: 100 • authority: 72

A waterfall is any point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls can be formed in several ways, but the most common method of formation is that a river courses over a top layer of resistant bedrock before falling onto softer rock, which erodes faster, leading to an increasingly high fall. Waterfalls have been studied for their impact on species living in and around them. Humans have had a distinct relationship with waterfalls since prehistory, travelling to see them, exploring and naming them. They can present formidable barriers to navigati…

Evidence: 68 • authority: 72

The Niagara Escarpment is an approximately 1,050-kilometre-long (650-mile) discontinuous, arc-shaped, but generally northward-facing escarpment, or cuesta, in Canada and the United States. The escarpment begins south of Lake Ontario and circumscribes the top of the Great Lakes Basin running from New York through Ontario, Michigan, and Wisconsin. The escarpment is the cliff over which the Niagara River plunges at Niagara Falls, for which it is named. The escarpment is a UNESCO World Biosphere Reserve. The reserve has the oldest forest ecosystem and trees in eastern North America. The Niagara Escarpment is not a fault line but the result of unequal erosion. The cliff-forming rock exposed alon…

Evidence: 57 • authority: 88

A Mechanistic Model of Waterfall Plunge Pool Erosion into Bedrock. Abstract Landscapes often respond to changes in climate and tectonics through the formation and upstream propagation of knickzones composed of waterfalls. Little work has been done on the mechanics of waterfall erosion, and instead most landscape‐scale models neglect waterfalls or use rules for river erosion, such as stream power, that may not be applicable to waterfalls. Here we develop a physically based model to predict waterfall plunge pool erosion into rock by abrasion from particle impacts and test the model against flume experiments. Both the model and experiments show that evolving plunge pools have initially high ve…

Evidence: 38 • authority: 72

The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, they include: the Atlantic Plain Province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachian Province, and the Central Lowlands Province. A majority of the rocks in Pennsylvania exposed at the surface are sedimentary and were deposited during the Paleozoic Era. Almost all of the metamorphic and igneous rocks are confined…

Evidence: 37 • authority: 88

Mass balance controls on sediment scour and bedrock erosion in waterfall plunge pools. Abstract Waterfall plunge pools experience cycles of sediment aggradation and scour that modulate bedrock erosion, habitat availability, and hazard potential. We calculate sediment flux divergence to evaluate the conditions under which pools deposit and scour sediment by comparing the sediment transport capacities of waterfall plunge pools (Qsc_pool) and their adjacent river reaches (Qsc_river). Results show that pools fill with sediment at low river discharge because the waterfall jet is not strong enough to transport the supplied sediment load out of the pool. As discharge increases, the waterfall jet s…

Evidence: 37 • authority: 88

Design and Application of Softer Formation Tungsten Carbide Rock Bits. ABSTRACT Life of the tungsten carbide tooth rock bit was greatly increased by the introduction to the industry of the O-ring sealed journal bearing design in 1969. With this development greater emphasis was then placed on cutting structure development. Innovative tooth shape designs and metallurgical improvements have allowed the application of carbide tooth rock bits to be extended into softer and softer formations. Continued bearing development has resulted in more consistent bit performance and a greater tolerance for higher rotary speed. This and the introduction of softer carbide tooth cutting structures have provid…

Evidence: — • authority: 72

A mushroom rock, also called a pedestal rock, rock pedestal, or gour, is a naturally occurring rock whose shape, as its name implies, resembles a mushroom. The rocks are deformed in a number of different ways: by erosion and weathering, glacial action, or from a sudden disturbance. Mushroom rocks are related to, but different from, yardang.

Evidence: — • authority: 72

A valley is an elongated low area often running between hills or mountains and typically containing a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas. At lower latitudes and altitudes, glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In areas of limestone bedrock, dry valleys may result from drain…

Evidence: — • authority: 72

Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called "risers". These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness. River terraces are the remnants of earlier floodplains that existed at a time when either a stream or river was flowing at a higher elevation before its channel downcut to creat…

Evidence: — • authority: 72

The geology of Minnesota comprises the rock, minerals, and soils of the U.S. state of Minnesota, including their formation, development, distribution, and condition. The state's geologic history can be divided into three periods. The first period was a lengthy period of geologic instability from the origin of the planet until roughly 1,100 million years ago. During this time, the state's Precambrian bedrock was formed by volcanism and the deposition of sedimentary rock and then modified by processes such as faulting, folding and erosion. In the second period, many layers of sedimentary rock were formed by deposition and lithification of successive layers of sediment from runoff and repeated…

Evidence: — • authority: 72

Kuntala Waterfall is a waterfall of Telangana state in India, located on Kadam river in Neradigonda mandal of Adilabad district. It is the highest waterfall in the state with a height of 150 feet. There is a story behind the name of this waterfall as 'Kuntala'. It is said that Dusyanthu's wife Shakuntala was mesmerized by the beauty of nature here and she used to bathe in this waterfall all the time. Locals say that the name of 'Shakuntala' has changed to 'Kuntala'. These waterfalls are in the dense forests inhabited by the Gonds. Kunta in Gondi and Telugu means pond. Kuntalu means several ponds. The waterfall originates from a confluence of several ponds that lead to the river Kadem. Forme…

Evidence: — • authority: 72

"Waterfalls" is a song by American girl group TLC, released on May 29, 1995, by LaFace and Arista as the third single from the group's second album, CrazySexyCool (1994). The song addresses the illegal drug trade, promiscuity, and HIV/AIDS. "Waterfalls" was the first number-one song to refer to AIDS, according to BMG's Jarett E. Nolan. Often considered one of the group's signature songs, "Waterfalls" was an international hit, topping the charts in many countries. The song spent seven weeks at No. 1 on the Billboard Hot 100, giving the group their second US No. 1; it was the No. 2 song of the year on the Billboard 1995 year-end chart. "Waterfalls" also peaked at No. 1 in New Zealand, Switzer…