A short history of nearly everything - Bill Bryson [31]
Among the questions that attracted interest in that fanatically inquisitive age was one that had puzzled people for a very long time—namely, why ancient clamshells and other marine fossils were so often found on mountaintops. How on earth did they get there? Those who thought they had a solution fell into two opposing camps. One group, known as the Neptunists, was convinced that everything on Earth, including seashells in improbably lofty places, could be explained by rising and falling sea levels. They believed that mountains, hills, and other features were as old as the Earth itself, and were changed only when water sloshed over them during periods of global flooding.
Opposing them were the Plutonists, who noted that volcanoes and earthquakes, among other enlivening agents, continually changed the face of the planet but clearly owed nothing to wayward seas. The Plutonists also raised awkward questions about where all the water went when it wasn't in flood. If there was enough of it at times to cover the Alps, then where, pray, was it during times of tranquility, such as now? Their belief was that the Earth was subject to profound internal forces as well as surface ones. However, they couldn't convincingly explain how all those clamshells got up there.
It was while puzzling over these matters that Hutton had a series of exceptional insights. From looking at his own farmland, he could see that soil was created by the erosion of rocks and that particles of this soil were continually washed away and carried off by streams and rivers and redeposited elsewhere. He realized that if such a process were carried to its natural conclusion then Earth would eventually be worn quite smooth. Yet everywhere around him there were hills. Clearly there had to be some additional process, some form of renewal and uplift, that created new hills and mountains to keep the cycle going. The marine fossils on mountaintops, he decided, had not been deposited during floods, but had risen along with the mountains themselves. He also deduced that it was heat within the Earth that created new rocks and continents and thrust up mountain chains. It is not too much to say that geologists wouldn't grasp the full implications of this thought for two hundred years, when finally they adopted plate tectonics. Above all, what Hutton's theories suggested was that Earth processes required huge amounts of time, far more than anyone had ever dreamed. There were enough insights here to transform utterly our understanding of the Earth.
In 1785, Hutton worked his ideas up into a long paper, which was read at consecutive meetings of the Royal Society of Edinburgh. It attracted almost no notice at all. It's not hard to see why. Here, in part, is how he presented it to his audience:
In the one case, the forming cause is in the body which is separated; for, after the body has been actuated by heat, it is by the reaction of the proper matter of the body, that the chasm which constitutes the vein is formed. In the other case, again, the cause is extrinsic in relation to the body in which the chasm is formed. There has been the most violent fracture and divulsion; but the cause is still to seek; and it appears not in the vein; for it is not every fracture and dislocation of the solid body of our earth, in which minerals, or the proper substances of mineral veins, are found.
Needless to say, almost no one in the audience had the faintest idea what he was talking about. Encouraged by his friends to expand his theory, in the touching hope that he might somehow stumble onto clarity in a more expansive format, Hutton spent the next ten years preparing his magnum opus, which was published in two volumes in 1795.
Together the two books ran to nearly a thousand pages and were, remarkably, worse than even his most pessimistic