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I’m currently reading John McPhee’s Annals of the Former World, which is discussing plate tectonics. He often gives figures for uplifts at subduction zones measured in tens of thousands of feet.

This got me wondering about how high the highest mountain in earth’s history must have been. At present, the highest mountain peak is Mt Everest, but perhaps at some time in the past another mountain exceeded its height. (Before India collided with the Asian mainland, it must have been somewhere else.)

Do we have any evidence of a specific mountain we believe was at some point higher than present-day Mt Everest? If so, what’s the speculated height, and what evidence leads us to conclude this?

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Any answer will have to be confined to speculation, because we'll never know the exact height of a mountain that's completely eroded away.

That said, it is likely that there were higher mountains. One good possibility is the mountain range created by the Alleghenian Orogeny during the Carboniferous Period, and which formed the backbone of Pangea until its breakup in the Triassic.

The Himalayas were formed by the collision of two continents, and it makes sense that such collisions create the highest mountains of all.

The Alleghenian collision between Euramerica and Godwana was much bigger. The mountains created by the collision were certainly much more massive than the Himalayas.

But higher? There's no way to tell for sure. We don't know what the rate of uplift was relative to the rate of erosion. The Himalayas' uplift (and erosion) is accelerated by a feedback loop involving the monsoon.


Expanding the definition of "highest mountain ", Earth has a mountain higher than Everest right now: The "Big Island" of Hawai'i, which is 10,000 meters (33,000 ft) from its base in the Pacific to its summit on Mauna Kea.

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  • $\begingroup$ Worth mentioning that Everest and Mauna Kea are close to the maximum feasible height for a mountain on Earth given the elastic strength of rock. So there may have been higher mountains, but they wouldn't have been much higher; rock wouldn't be strong enough to bear the weight. $\endgroup$
    – Andy M
    Commented May 13 at 15:14
  • $\begingroup$ @AndyM I've seen such wildly variable estimates for the maximum feasible height (10000-15000m) that I felt mentioning it would only confuse things. $\endgroup$
    – Spencer
    Commented May 13 at 17:51
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It would be difficult to identify an individual peak of former mountains. Mountain ranges are different, however.

Despite the highest peak of the Petermann Ranges, in Australia, being 1158 meters above sea level; the range, which extends for

320 km across the border between Western Australia and the southwest corner of the Northern Territory

is thought to once have been of equivalent height as the Himalayas.

The loss of height and mass was due to erosion over hundreds of millions of years. Some of the eroded material formed the sandstone that eventually lead to the formation of Uluru.

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Earth' orogeny (Mountain building) is unique process occured for eons. The Himalayas of which Everest is one, formed just shy 50 million years ago when tetonic plates of India and Asia folded over one another created the largest peak average heights. The geologic forces that erode mountains may have had higher peaks.

Mount denali in Alaska is 60 million years old, and 20,000 feet high, 9000 feet shorter than everest, but 10 million years older, such may eroded faster in time. Never the less the mountain continues to grow. Everest is getting taller (average fraction millimeter a year)

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