Near the summit of Mount Everest, at an altitude where airliners cruise, climbers cross a band of grey-yellow limestone. Look closely at that rock and you find the remains of sea creatures — fragments of crinoids and other marine life that once lived on the floor of a warm ocean. The highest point on Earth is made of seabed. It is the single most eloquent fact in geology, and the story behind it is still in motion: the Himalayas are growing to this day, and the mountains keep issuing receipts in the form of earthquakes.
The story begins with a runaway continent. Over a hundred million years ago, the landmass that is now India broke away from the southern supercontinent of Gondwana and set off northwards across an ocean geologists call the Tethys. It moved absurdly fast by tectonic standards — at times perhaps fifteen to twenty centimetres a year, several times normal continental drift. Around fifty million years ago it ran into Eurasia. Continental crust is too buoyant to be swallowed into the mantle, so instead of one plate sliding neatly beneath the other, the two crumpled. The Tethys seabed, with all its shells and sediments, was squeezed, folded and thrust skywards; the crust beneath the collision zone doubled in thickness, floating the Tibetan Plateau — the "roof of the world" — to an average height of around four and a half thousand metres.
Still rising
The collision has never stopped. India continues to push into Asia at a few centimetres a year, and satellite positioning shows the High Himalaya rising by roughly five millimetres annually — a fraction of the rate fingernails grow, applied to a mountain range. Rivers and glaciers grind the peaks down almost as fast as tectonics lifts them, which is why the range's height is a running battle rather than a simple ascent. Everest's official height has itself been a diplomatic saga: after years of competing figures, China and Nepal jointly announced a measurement of 8,849 metres (8,848.86, to be precise) — settling, at least for now, a number first fought over in the nineteenth century.
That first fight is a great story in its own right. In 1852, Radhanath Sikdar, a Bengali mathematician working for the Great Trigonometrical Survey of India, computed from distant theodolite readings that the obscure "Peak XV" was the highest mountain in the world. The result, announced in 1856, was 29,002 feet — and a beloved tale claims the surveyors added two feet so the figure would not look like a lazy rounding of 29,000. The story is endlessly repeated and quite possibly embellished; the published number, at least, is a matter of record. The peak was then named after Sir George Everest, the survey's former chief — who by most accounts never saw the mountain, objected to having his name attached to it, and pronounced that name "EEV-rest". Tibetans had long called it Chomolungma, often rendered "Goddess Mother of the World"; Nepal's official name, Sagarmatha, was adopted in the twentieth century.
Earthquakes as receipts
If the uplift is the invoice, the earthquakes are the receipts. India's push does not feed smoothly into the mountains: strain accumulates for decades or centuries along the great faults at the range's base, then releases in seconds. In April 2015 the magnitude-7.8 Gorkha earthquake struck Nepal, killing roughly nine thousand people, toppling historic towers in Kathmandu and triggering a deadly avalanche on Everest itself; the ground beneath the Kathmandu region lurched southwards by well over a metre. The 1934 Bihar–Nepal earthquake was deadlier still, and the 1950 Assam earthquake at the range's eastern end, around magnitude 8.6, ranks among the most powerful continental quakes ever recorded. Each catastrophe is the collision doing in an instant what it usually does imperceptibly.
The range the collision built holds nearly every terrestrial superlative. Its name is Sanskrit — hima and alaya, "abode of snow". All fourteen of the world's peaks above eight thousand metres stand in the Himalaya and the neighbouring Karakoram — a distinction worth remembering, since K2, the second-highest, is a Karakoram peak, not strictly a Himalayan one. And in the Kali Gandaki gorge of Nepal, which cuts one of the deepest valleys on Earth between the giants Dhaulagiri and Annapurna, pilgrims still gather black ammonite fossils — spiral shells from the vanished Tethys, venerated as sacred shaligram stones.
That is the Himalaya in a single image: a wall of former ocean floor, pushed a little higher every year, worshipped with the fossils of the sea it replaced.
Quiz nuggets
- Marine fossils, including crinoid fragments, occur in the limestone near Everest's summit — remnants of the ancient Tethys Ocean floor.
- India collided with Eurasia around fifty million years ago and still pushes north, raising the High Himalaya by roughly five millimetres a year.
- China and Nepal jointly fixed Everest's height at 8,848.86 metres; Radhanath Sikdar first computed Peak XV as the world's highest in 1852.
- The 2015 Gorkha earthquake in Nepal, magnitude 7.8, killed roughly nine thousand people and shifted the ground beneath Kathmandu by over a metre.
- K2 stands in the Karakoram, not the Himalaya proper; "Himalaya" is Sanskrit for "abode of snow".