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Groundbreaking discovery finally proves rain can move mountains
- adolph 6y agoStudy of Himalayan erosion. "When a cosmic particle from outer space reaches Earth, it is likely to hit sand grains on hillslopes as they are transported toward rivers. When this happens, some atoms within each grain of sand can transform into a rare element. By counting how many atoms of this element are present in a bag of sand, we can calculate how long the sand has been there, and therefore how quickly the landscape has been eroding," Dr. Adams said.
- philipkglass 6y agoHe's referring to beryllium-10, which is mostly generated by cosmic ray interactions with nitrogen and oxygen in the atmosphere. The Be-10 subsequently washes out of the atmosphere with precipitation and tends to bind in surface soils. It has a half life of 1.39 million years so it is useful for dating various geological phenomena. https://en.wikipedia.org/wiki/Beryllium-10 https://en.wikipedia.org/wiki/Beryllium-10 You can see how this beryllium isotope was used in the original paper "Climate controls on erosion in tectonically active landscapes" (linked by sradman in comment https://news.ycombinator.com/item?id=24812181 https://news.ycombinator.com/item?id=24812181) within the Materials and Methods section of the paper.
- adolph 6y agoIt is beautiful how the study of the very small (cosmic ray interacting with nitrogen and oxygen) can add so much to the study of the very large (monsoons and the Bhutan Himalaya).
- sradman 6y agoThe paper Climate controls on erosion in tectonically active landscapes [1]: > The ongoing debate about the nature of coupling between climate and tectonics in mountain ranges derives, in part, from an imperfect understanding of how topography, climate, erosion, and rock uplift are interrelated. Here, we demonstrate that erosion rate is nonlinearly related to fluvial relief with a proportionality set by mean annual rainfall. [1] https://advances.sciencemag.org/content/6/42/eaaz3166 https://advances.sciencemag.org/content/6/42/eaaz3166
- cblconfederate 6y ago"Earthshattering" would be a better word
- nielsbot 6y agoGroundbreaking works too :)
- mannykannot 6y ago"...scientists have also believed rain can erode a landscape quickly enough to essentially 'suck' the rocks out of the Earth, effectively pulling mountains up very quickly." I do not understand this, unless the point is that rainfall, by eroding valleys, reduces the weight of a mountain range, allowing tectonic forces to raise the ridges and peaks faster than otherwise.
- vhold 6y agoI'm confused as well. Another possibility is the "up" is relative? If there is a mountain already buried in looser soils, rain could wash away and expose the mountain, which will appear to be going up, because everything else is going down.
- tomrod 6y agoCrust floats on the mantle. Mountains are areas where the crust is thick and it goes down into the mantle further than less thick areas. As the weight from the top is removed, that can push up areas from down below. We tend to think of mountains as stable things with the constant stress underneath, rather than a layer of congealed fat on top of a warm stove (or, a lava lamp). But the latter is a better model for geologic behaviour over long periods of time.
- geoid 6y agoThis is correct. The earth is ductile at long time periods, and mountains maintain isostatic equilibrium as the tops are eroded away. The article quote is absurd. Source: my earth science PhD.