A vocabulary of landscape — a landscape of words
1083 entries
turbidite
A turbidite is the deposit left by a turbidity current: an avalanche of sediment-laden water that runs down a continental slope at speed, sometimes for hundreds of miles, and spreads out on the deep floor. Each event lays a single bed that is coarse at the bottom and fine at the top, because the heaviest grains settle first, and a sequence of them stacks like a set of pages.
Etymology
The word is built on the Latin for muddy or disturbed, the same root as turbid and turbulence. The standard internal sequence of divisions within one bed is called the Bouma sequence, after the Dutch geologist who described it in 1962, and reading a turbidite means identifying which of those divisions are present.
Notes
The mechanism was established by a cable break. In 1929, an earthquake on the Grand Banks off Newfoundland cut a series of transatlantic telegraph cables one after another, and the times at which each stopped working gave a speed for whatever was traveling down the slope. Working backward from the sequence, the current was moving at over forty miles an hour, which was the first hard evidence that such flows existed.