Groundbreaking discovery finally proves rain can move mountains

Post by OlympusMonds » Sun, Oct 18, 2020, 12:34 AM UTC

geoid wrote: post #10

tomrod wrote: post #8

Earlier quoted context omitted.

Crust 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 geol…

This 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.

Post by raws » Sun, Oct 18, 2020, 2:31 AM UTC

geoid wrote: post #13

tomrod wrote: post #11

Earlier quoted context omitted.

I love your username. I spend a lot of time with Census Tigerfiles. GEOID is life!

Thanks. There's another meaning of geoid, which is the shape of mean sea level of the globe. The height of sea level varies according to the local strength of gravity. When they first put up satellites that could accurately map sea level, it gave us the amazing maps of the sea floor. Basically, the sea surface subtly mimics the features of the sea floor.

Post by adolph » Sun, Oct 18, 2020, 3:05 AM UTC

philipkglass wrote: post #4

adolph wrote: post #2

Study 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 landsc…

He'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 You can see how this beryllium isotope was…

Post by OlympusMonds » Sun, Oct 18, 2020, 3:16 AM UTC

bigbubba wrote: post #15

OlympusMonds wrote: post #12

Earlier quoted context omitted.

Yes, you're right, it is the isostatic unloading that they're referring to - but in regards to the 'sucking', they seem to mean that the semi-localised unloaded of the top of crust (via rain, river incision) creates a zone of lower lithostatic pressure, and so that area ends up getting pushed up to maintain isostatic equilibrium. Not truly a 'sucking', but as an analogy, I think it's OK. It's more easily seen as part…

Does anything truly 'suck'? When you drink a milkshake with a straw, the milkshake is pushed up your straw by the atmosphere..

Post by emosenkis » Sun, Oct 18, 2020, 6:07 AM UTC

raws wrote: post #14

geoid wrote: post #13

Earlier quoted context omitted.

Thanks. There's another meaning of geoid, which is the shape of mean sea level of the globe. The height of sea level varies according to the local strength of gravity. When they first put up satellites that could accurately map sea level, it gave us the amazing maps of the sea floor. Basically, the sea surface subtly mimics the features of the sea floor.

I think I recall being thaught that water followed the gravity pull which was greater around the equator than the poles which would explain why with the poles melting, the equatorial regions would be the most affected by the subsequent seas rise. Is this wrong? Where can I see a good sea map? Thanks! Guess I just went and looked at a Geoid map and I was lied to, EU is in big trouble!