ABSTRACT
When a telegraph cable was to be laid for the first time between Great Britain and the United States, it was immensely important to know the exact nature of the bottom of the sea so as to guard against the costly cable being frayed or cut. So in 1857 the Admiralty commissioned a survey of the seabed over the whole line of the cable. Thomas Huxley had specimens from the survey sent to him for analysis, and found that almost the whole of the central plain beneath the North Atlantic, from Valentia on the west coast of Ireland to Trinity Bay in Newfoundland, was covered by a fine chalky mud that, when brought to the surface, dried into a greyish-white substance. If you are so inclined, you can write with it on a blackboard, as he did in his 1868 lecture, On a Piece of Chalk. Huxley said that when he examined a section of this substance under the microscope, he saw congregated together innumerable minute chambered skeletal bodies, beautifully constructed of calcium carbonate in a variety of coccolith forms and on average not larger than a hundredth of an inch across.
