highest mountain ever
November 9, 2016 7:57 PM Subscribe
Mount Everest is 29,029 ft. Mauna Kea is something around 33,000 ft from base to peak. Since Olympus Mons is 69,650 ft about the mean for Mars, these are not absolutes for Earth. What is the highest mountain in Earth's history,and how high was it?
This is a fascinating question, and since I'm not a geologist I'm not qualified to answer it. But since there's only one other answer, I'd say that there were potentially far higher mountains in Earth's history, but that we have no real way of calculating their height.
Mt Everest was formed by the ongoing collision between the Eurasian and Indian continental plates. It continues to grow, as they collide, but it's also being eroded. So all other things being equal, faster collisions give less time for erosion. I think the consensus used to be that plate tectonics has been slowing as the Earth cools, but recent research has thrown doubt on that. In any event, the average speed doesn't tell you what the maximum speed and maximum displacement was. I would expect that over the past billion-odd years there have been more rapid collisions with greater displacement, and therefore higher mountains induced by plate movement. The only intrinsic constraint is probably the angle of repose.
As for volcanic mountains, like Mauna Kea, I expect that volcanoes have a maximum height that depends on the maximum pressure of the magma that forms them. But consider the Deccan Traps, that once covered about half of India with a shield two kilometres thick. We really have no idea how powerful volcanoes can be, or have been in the past.
Another way mountains may have been formed is by meteor impacts. There's a pretty substantial theory that the Moon was created by just such an impact - if so, the landscape must have been so chewed up that there may have been short-lived mountains of almost any height. Leaving that aside, the Chicxulub Crater is more than 180 km wide and is thought to have been formed by a bolide more than 10km across. Very briefly, then, at the moment of impact Earth had a mountain at least 10 km high. I don't know what height the walls or central peak would have reached, but I suspect someone knows how that could be calculated.
Anyway, I think the best answer I can give is: we don't know, but our knowledge of geology implies that there may have been much higher mountains in Earth's past.
posted by Joe in Australia at 9:21 PM on November 10, 2016
Mt Everest was formed by the ongoing collision between the Eurasian and Indian continental plates. It continues to grow, as they collide, but it's also being eroded. So all other things being equal, faster collisions give less time for erosion. I think the consensus used to be that plate tectonics has been slowing as the Earth cools, but recent research has thrown doubt on that. In any event, the average speed doesn't tell you what the maximum speed and maximum displacement was. I would expect that over the past billion-odd years there have been more rapid collisions with greater displacement, and therefore higher mountains induced by plate movement. The only intrinsic constraint is probably the angle of repose.
As for volcanic mountains, like Mauna Kea, I expect that volcanoes have a maximum height that depends on the maximum pressure of the magma that forms them. But consider the Deccan Traps, that once covered about half of India with a shield two kilometres thick. We really have no idea how powerful volcanoes can be, or have been in the past.
Another way mountains may have been formed is by meteor impacts. There's a pretty substantial theory that the Moon was created by just such an impact - if so, the landscape must have been so chewed up that there may have been short-lived mountains of almost any height. Leaving that aside, the Chicxulub Crater is more than 180 km wide and is thought to have been formed by a bolide more than 10km across. Very briefly, then, at the moment of impact Earth had a mountain at least 10 km high. I don't know what height the walls or central peak would have reached, but I suspect someone knows how that could be calculated.
Anyway, I think the best answer I can give is: we don't know, but our knowledge of geology implies that there may have been much higher mountains in Earth's past.
posted by Joe in Australia at 9:21 PM on November 10, 2016
The isostatic limit on Mars allows for greater mountains... there's simply less gravity there. There's no way to know what the highest mountain ever was, but they can estimate the theoretical highest possible on earth, which varies for continental crusts and oceanic.
posted by yeti at 12:35 PM on November 12, 2016
posted by yeti at 12:35 PM on November 12, 2016
This seems relevant, and surprisingly timely: Dinosaur-killing asteroid turned planet Earth inside-out
posted by Joe in Australia at 6:32 PM on November 22, 2016
[...] First the [Chicxulub] asteroid blasted through almost all of Earth’s crust, propelling rocks from the bottom of the crust and lifting them 25 kilometres within 10 minutes. At the rim of the newly forming crater, a mountain range higher than the Himalayas lifted and collapsed within three minutes, leaving a halo of basement rock in a geological feature called a peak ring. At the centre, a massive peak of rock splashed upward, fluid-like, before collapsing again – much like the splash of a sugar cube in a cup of hot tea.So the Chixculub impact was about 65 million years ago; that's about one and a half percent of Earth's age; you'd have to think there have been many more and larger impacts than that in the deep past. And if it's impact created a range higher than the Himalayas, then larger ones could, as I said, have been almost any size.
posted by Joe in Australia at 6:32 PM on November 22, 2016
Response by poster: Another way mountains may have been formed is by meteor impacts.
The central peak of Rheasilvia on Vesta is 20 to 25 km high!
posted by the man of twists and turns at 10:49 PM on March 28, 2017
The central peak of Rheasilvia on Vesta is 20 to 25 km high!
posted by the man of twists and turns at 10:49 PM on March 28, 2017
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posted by nickggully at 9:41 AM on November 10, 2016