River channels on three worlds reveal a history of shifting landscapes
vendredi 19 mai 2017, 21:15 , par Ars Technica
Enlarge / Ligeia Mare, the second-largest body of liquid hydrocarbons on Titan. (credit: NASA/JPL-Caltech/ASI/Cornell)
At this point, we’ve worked out the basics of the processes that produced the topography around us here on Earth. But other worlds in our solar system have very different landscapes that could partly be the result of foreign processes. The distant glimpses we get of these worlds make revealing those landscape histories a real challenge. Reconstructing a crime from a detailed inspection of a crime scene is one thing, doing it through a telescope is another.
Rivers are, in a way, topography bystanders that always flow downhill. The channels they carve certainly modify the landscape, but their paths reflect the elevations around them. They can also tell you about past topography if you know how to look. A team led by City University of New York researcher Benjamin Black sought to apply this concept not just to the Earth, but also to the two other worlds where we see river channels—Mars and Titan.
The researchers distinguished between long-wavelength topography (think continents and ocean basins on Earth) and short-wavelength topography (think mountain ranges within continents). The differing scales signify different processes, with smaller features resulting from local interactions between Earth’s tectonic plates rather than the fundamental difference between continental and ocean crust.
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