Taxonomy term

river

Humans accidentally created new rivers in Europe

Meandering rivers that flow through and transport sediment to deltas often split off from their main courses and flow in different directions. This process, called avulsion, happens naturally when a river overflows its banks and the floodwaters carve out a new course for the river to follow. But humans can also trigger avulsions by changing the shape of the landscape, and in a new study, scientists report that people have been doing this for a very long time.

15 Feb 2019

Mighty Mekong cut by monsoon, not tectonics

The rivers draining the Tibetan Plateau are some of the largest, longest and most deeply incised waterways in the world. For decades, most geologists assumed that these river canyons were cut as the plateau was uplifted following the initial collision of the Indian subcontinent with Asia. However, recent studies have found that the plateau was already elevated by 40 million years ago — roughly 20 million years before the deep canyons formed. 

06 Feb 2019

Night lights reveal that people move as rivers rise

Flooding is one of the most damaging natural hazards, so it’s no surprise that many people resettle farther from rivers after catastrophic flooding. A new study finds that the distance that people move from a given river depends on the degree of flood protection in place, with people rebuilding closer to rivers that offer high levels of structural flood protection, such as levees and dams, than they do to rivers without such protections.

28 Dec 2018

Dry rivers secretly star in carbon cycle

In arid environments, some seasonal rivers and streams spend more time as dry riverbeds than they do as flowing waterways. A new study is giving scientists a clearer understanding of how these intermittently dry streambeds contribute to the global carbon cycle.

02 Oct 2018

Charting 500 years of Mississippi floods

The Mississippi River is notorious for flooding its muddy banks, with many critical areas actively managed by the Army Corps of Engineers to control flooding. But despite all the controls, major floods still occur. 

01 Aug 2018

Diamonds and the Eocene climate of the Bell River Basin

Diamonds mined from the kimberlite pipes of the Lac de Gras diamond field in Northwest Territories, Canada, are among the world’s youngest known diamonds, dating from 75 million to 45 million years ago. In some cases, when the magmas that carried these diamonds to Earth’s surface encountered water-saturated rock at shallow depths, violent steam explosions called phreatomagmatic eruptions resulted. Such explosions can form volcanic craters known as maars, which often fill with water and accumulate lake sediment, along with soil and vegetation that collapse into them from their margins. In the case of the Panda kimberlite pipe at the Ekati Mine in the Lac de Gras area, maar sediments accumulated far below the surrounding terrain, such that they were later buried under glacial deposits rather than being eroded away by ice sheets during the past million years. Wood and other organic materials were entombed and preserved in their natural state, thereby preserving shreds of the Paleo-Bell River Basin.

25 Jul 2018

Saglek Basin sediments suggest a Grand Canyon connection

Pollen makes an ideal fossil. Pollen grains — each only a few tens of microns in diameter — are produced in astronomical quantities by plants and record information about the ecosystem from which they came, thus providing a way to reconstruct past environments. Additionally, pollen is composed of a highly stable organic substance, sporopollenin, which resists decay as well as the high heat and pressure associated with deep burial, lithification and tectonism. It is so resistant, in fact, that it can be eroded from rock and recycled into younger sediments, a process recognized in the 1980s by V. Eileen Williams of the University of British Columbia in her studies of Paleo-Bell River sediments deposited in the Labrador Sea.

25 Jul 2018

The Paleo-Bell River: North America's vanished Amazon

With similar geologic and tectonic histories, including a continuous mountain cordillera along their western margins, why does South America have a massive river draining a continentwide basin but North America does not? Before the Pleistocene, it did.
25 Jul 2018

Travels in Geology: Rafting the Salmon River through the Idaho Batholith

Rafting down the Main Salmon River, which courses north and then west across northern Idaho, takes you by Precambrian metamorphics and the granites of the Idaho Batholith. Six to eight days later, your trip concludes as you float past what was once the edge of North America, and over former island arcs sutured onto the continent during the Mesozoic.
06 Jun 2018

From farm to filter: Restored wetlands remediate nitrogen pollution

The early 20th-century invention of a nitrogen-fixation process revolutionized agriculture and made it possible to feed the planet’s growing population. But nitrogen runoff is polluting our waterways and suffocating aquatic life. Now, researchers looking for ways to reverse that trend are turning farmland into wetlands to filter nitrogen from streams and rivers.
20 Apr 2018

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