Taxonomy term

geomorphology

Spawning salmon engineer landscapes

All animals depend on their ecosystems for habitat. And, in turn, many animals impact their ecosystems by engineering the landscape to suit their needs. Beavers provide an iconic example of ecosystem engineering when they build dams, which influence streams and wetlands. The engineering efforts of salmon, meanwhile, can even shape the bedrock of the watersheds in which they live, according to a recent study that modeled the evolution of those watersheds over several million years.

23 Feb 2018

Searching for the ancestors of meandering rivers

It might be difficult to imagine Earth devoid of vegetation, but for billions of years the sun shone, winds blew and rivers flowed on a planet without any plants.

21 Jun 2016

Due diligence in river incision data

As great equalizers of topography, rivers and streams whittle down landscapes by alternately scouring away broad flat swaths of sediment and rock, and incising deeply through them. If a landscape — a mountain range, for example — is being uplifted by tectonic forces, this whittling occurs even faster. River incision rates in particular are thus often used to infer past rates of rock uplift. But determining incision rates themselves is not clear-cut. In a new study in Geology, scientists look at one complicating factor in such calculations, what the authors call the “unappreciated effects of streambed elevation variability” on measuring river incision rates.
 
21 Nov 2015

Wormholes may limit landslides

When Emma Harrison, a graduate student at the University of Pennsylvania, began digging trenches in the Luquillos Mountains of Puerto Rico to study how the soil mantle responds to rapid changes in erosion, she couldn’t help but notice that the thick soils were chock-full of wriggling worms. Intrigued by the worms’ abundance and prodigious activity at her field site, Harrison wondered whether their presence could be influencing weathering and erosion in the Luquillos. 

09 Nov 2015

Sculpting the Alps

Mountains typically get steeper the higher you climb. The European Alps are an exception: Beginning at altitudes between about 1,500 and 2,000 meters, most slopes in the range tend to become less steep with increased elevation. This is largely caused by ancient glaciers, which scoured away much of the rock from the tops of the Alps. However, the steepness of alpine slopes also decreases in areas beyond the reach of glaciers, although the reasons why have remained elusive. New research is revealing how tectonic and fluvial forces have also helped shape the Alps’ unusual topography.
 
04 Oct 2015

Sediment load shapes rivers

The amount of sediment carried in meandering rivers influences how quickly the bends in those rivers migrate back and forth, according to recent research in Nature Geoscience addressing a longstanding question regarding river evolution. Meanders form when flowing water erodes one riverbank while simultaneously depositing sediment on the opposite bank, gradually creating more and more pronounced U-shaped bends. Sometimes, the rivers cut new channels across the narrow necks of such bends, isolating the abandoned meanders to form distinctive oxbow lakes. 
 
04 Jul 2015

Pre-settlement erosion rates illuminated

Humans are one of the most powerful erosive agents on Earth, moving copious amounts of sediment to and fro, mainly through agriculture and development. But quantifying how much we actually move — often a necessary step for developing sustainable land management practices — hinges on determining erosion rates in an area before humans intervened. A new study using surface exposure dating to estimate pre-colonial erosion rates in the southeastern U.S. has now clarified the natural background rate in more detail than ever before, revealing the dramatic human impact on the regional landscape.

 
31 May 2015

Down to Earth With: David Montgomery

From the length and breadth of his body of work, you might assume that David Montgomery, a geomorphologist at the University of Washington in Seattle, is approaching the end of a highly successful career. After all, among other accomplishments, he pioneered our understanding of how river channels shape landscapes, explored how glaciers and climate determine the height of the world’s highest mountain ranges, and helped elucidate how erosion has shaped human civilizations through time. 

 
15 Nov 2013

Down to Earth With: Geomorphologist Gregory Tucker

As an undergraduate anthropology student, Gregory Tucker thought math was a boring subject with abstract rules that didn’t relate to his life. Today, that “boring” subject provides the foundation for Tucker’s innovative research involving numerical modeling and unique field studies that recently earned him the European Geosciences Union’s 2012 Ralph Alger Bagnold Medal, one of the highest prizes in geomorphology.

13 Jul 2012