The Hyakumeizan of relative height

A philosophical attempt to upset the established order

Height above sea-level isn’t everything, I realised while musing on the difficulty of defining a mountain – a topic touched on in the previous post. I mean, if you climb to 4,810 metres in western Europe, you are standing on top of Mt Blanc, with the world laid out at your feet. But the same altitude in Tibet hardly raises you above the level of the dusty plateau.

The view from relative altitude

Fukada Kyūya made a nod towards that resolving that awkwardness in the afterword to his One Hundred Mountains of Japan. A mountain’s height, he suggests, is one thing; its stature quite another. In the end, though, his choice of mountains is purely personal, based mainly on their aesthetic and historical appeal. Thus the Hyakumeizan author neatly sidesteps the philosophical question of what constitutes a mountain.

Others have taken a more rigorous approach to the problem. The other day I happened on a list of one hundred mountains of the world ranked by their “primary factor” or prominence. Prominence here is defined as the minimal vertical drop from the summit one has to descend before one can ascend a higher peak. In effect, it is a measure of how far a mountain stands proud of its surroundings.

Relatively high

In this ranking, Mt Everest is still Top Mountain; indeed, it has to be, by definition, for no higher peak can be ascended. What is interesting about this ranking by prominence is what happens lower down the table. Aconcagua (6962 metres) vaults over the heads of numberless Himalayan peaks into second place. And Mt Blanc, as befits its lordly eminence over the lesser Alps, makes it all the way up into 11th place.

Clearly, it helps to be an “island peak” if you want to make a good showing in this table. As a result, big volcanoes do well – some might say disproportionately so. Even modest Mt Fuji (3776 metres) is promoted to 35th place. For their part, Kilimanjaro (5895 metres) is up there in fourth place, Damavand (5610 metres) in 12th, and Mauna Kea (4205 metres), the roof of the Hawaiian islands, in 15th.

Mention of Mauna Kea made me wonder, though. Isn’t this ranking by prominence just as arbitrary as the traditional ranking of mountains by absolute height above sea level? For, in reality, Mauna Kea rises not from the sea’s surface but from the sea floor, which on average is more than 4,800 metres deep in these parts. So the real Mauna Kea is a structure that rises almost 9,000 metres from its base – higher than Everest.

Top of the world?

This doctrine of “real topographical relief” could dangerously subvert the established order. And, in the hands of Koaze Takashi, a professor of geography at Meiji University, it does just that. Measuring from the depths of the nearby Japan Trench, reckons the professor, Mt Fuji rises a breath-taking 12,000 metres above its base. And, he estimates, Everest could only rival that elevation if the sediments in the Ganges Basin were excavated down to the offshore bedrock.

Could it be that, in terms of true planetary topography, Mt Fuji is now the highest mountain in the world?

References

The Earth: an intimate history, by Richard Fortey, for the maunderings about Mauna Kea.

Yama wo yomu (Reading mountains) by Koaze Takashi, Professor of Geography at Meiji University.