Call it an alluvial face-off.
On the southern end of Severny Island in the Russian Arctic, rivers rush down from rugged terrain flanking a broad valley.
Upon reaching flatter ground, the waters slow and distribute sediment into cone-shaped features calledalluvial fans.
Several appear in opposing orientations alongside a braided river in this Landsat 9image.
Severny Island is a mountainous, uninhabitedlandmass in the frigid high latitudes of the Northern Hemisphere.
Part of the Novaya Zemlyaarchipelago, the island is largely covered in glacial ice.
Some glaciers, especially in the north, terminate in the sea, while others end on land, feeding meltwater into glacial streams.
Sediment-laden streams, along with the island’s topography, create favorable conditions for the formation of alluvial fans.
The features typically appear at the base of steep mountain ranges, where narrow river channels open onto flatter terrain.
There, rivers can slow, divide into smaller channels, anddeposit sediment.
Over time, the channels migrate back and forth to build up fan-shaped deposits.
Dueling fans line several northwest-southeast-trending valleys in the wider view below.
Seasonal snowmelt andglacial runofflikely keep Severny’s rivers supplied with ample fan-building material.
Hydrologists notethat higher river flows during the warmer months, driven by snowmelt, can carry more sediment out of the mountains.
Glaciers also produce large volumes of eroded material as they grind downslope, some of which flushes out in meltwater.
Smaller, land-terminating mountain glaciers, like those on southern Severny Island, are particularly prone to melting as theatmosphere warms.
Severny’s ice is relatively understudied due to its remoteness, but satellite observations give scientists an understanding of its health.
Recent analyses incorporatingdigital elevation modelsfound that land-terminating glaciers across the Novaya Zemlya archipelago thinned during the2000sand2010s, especially at lower elevations.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from theU.S. Geological Survey. Story by Lindsey Doermann.
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Małecki, J.Recent contrasting behaviour of mountain glaciers across the European High Arctic revealed by ArcticDEM data.The Cryosphere, 16, 2067–2082.
Melkonian, A.K.,et al.Recent changes in glacier velocities and thinning at Novaya Zemlya. Remote Sensing of Environment, 174, 244-257.
NASA Earth ObservatoryNovaya Zemlya. Accessed July 13, 2026.
National Geographic SocietyAlluvial Fan. Accessed July 13, 2026.
Science Education Resource Center, Carleton CollegeCold climate conditions as a driver of alluvial fan deposition in the Lost River Range, Idaho, USA. Accessed July 13, 2026.
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