TributaryA tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage basin of its surface water and groundwater, leading the water out into an ocean. The Irtysh is a chief tributary of the Ob river and is also the longest tributary river in the world with a length of . The Madeira River is the largest tributary river by volume in the world with an average discharge of .
GravelGravel (ˈɡrævəl) is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentary and erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gravel is classified by particle size range and includes size classes from granule- to boulder-sized fragments. In the Udden-Wentworth scale gravel is categorized into granular gravel () and pebble gravel (). ISO 14688 grades gravels as fine, medium, and coarse, with ranges for fine and for coarse.
ShoalIn oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It often refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars.
SavaThe Sava (ˈsaːvə; ˈsàːʋa, sǎːʋa; Сава, Száva) is a river in Central and Southeast Europe, a right-bank and the longest tributary of the Danube. It flows through Slovenia, Croatia and along its border with Bosnia and Herzegovina, and finally through Serbia, feeding into the Danube in its capital, Belgrade. The Sava forms the main northern limit of the Balkan Peninsula, and the southern edge of the Pannonian Plain. The Sava is long, including the Sava Dolinka headwater rising in Zelenci, Slovenia.
Illinois RiverThe Illinois River (Inoka Siipiiwi) is a principal tributary of the Mississippi River and is approximately long. Located in the U.S. state of Illinois, the river has a drainage basin of . The Illinois River begins with the confluence of the Des Plaines and Kankakee rivers in the Chicago metropolitan area, and it generally flows to the southwest across Illinois, until it empties into the Mississippi near Grafton, Illinois. Its drainage basin extends into southeastern Wisconsin, northwestern Indiana, and a very small area of southwestern Michigan in addition to central Illinois.
Missouri RiverThe Missouri River is the longest river in the United States. Rising in the Eastern Centennial Mountains of the Bitteroot Range of the Rocky Mountains of Southwestern Montana, the Missouri flows east and south for before entering the Mississippi River north of St. Louis, Missouri. The river drains a sparsely populated, semi-arid watershed of more than 500,000 square miles (1,300,000 km2), which includes parts of ten U.S. states and two Canadian provinces.
Meander cutoffA meander cutoff is a natural form of a cutting or cut in a river occurs when a pronounced meander (hook) in a river is breached by a flow that connects the two closest parts of the hook to form a new channel, a full loop. The steeper drop in gradient (slope) causes the river flow gradually to abandon the meander which will silt up with sediment from deposition. Cutoffs are a natural part of the evolution of a meandering river. Rivers form meanders as they flow laterally downstream, see sinuosity.
Sarasvati RiverThe Sarasvati River () is a deified river first mentioned in the Rigveda and later in Vedic and post-Vedic texts. It played an important role in the Vedic religion, appearing in all but the fourth book of the Rigveda. As a physical river, in the oldest texts of the Rigveda it is described as a "great and holy river in north-western India," but in the middle and late Rigvedic books it is described as a small river ending in "a terminal lake (samudra).
StratumIn geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either bedding surfaces or bedding planes. Prior to the publication of the International Stratigraphic Guide, older publications have defined a stratum as either being either equivalent to a single bed or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both bed and lamina.
Conglomerate (geology)Conglomerate (kənˈɡlɒmərɪt) is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts. A conglomerate typically contains a matrix of finer-grained sediments, such as sand, silt, or clay, which fills the interstices between the clasts. The clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay. Conglomerates form by the consolidation and lithification of gravel.
