Geology

Early observations on rocks were greatly conditioned by man's rather few means of access to the interior of the earth. In Italy notes had been made on volcanoes from Leonardo onwards ; in Germany, notes on mines from Agricola onwards ; in most countries, notes on fossils. In France about 1750, extinct volcanoes began the train of decisive discoveries. In Germany, not much later, mining provoked the serious classification of rocks. In Great Britain the surface cuttings and canals of the agricultural and industrial revolutions aroused the curiosity of Hutton and W. Smith. In the early work, partly palaeontological as it was, botanists bore a large share.

Leonardo da Vinci, Giordano Bruno, Stevinus, and other men of the Renaissance, with their vivid freedom from tradition, at once reached such common-sense conclusions as, that the rivers had sculptured the valleys, that some rocks had once been molten, that the sea, which is (Bruno) always near active volcanoes, must have some connection with them, that the land and the sea may not always have been in their present positions. But the clarity of these early views was soon lost. It was unsupported by work in the field, and put side by side with pre- scientific ideas. Fossils, for example, were Sports of Nature played on mankind, or the earth's imperfect successes in its efforts at the (spontaneous) generation of life.

Agricola (1494—1558) was a recognised mining expert. He made observations on crystals, their cleavage, lustre, colour, hardness, and was among those whose imagination was struck by those columnar formations of basalt (such as the Giant's Causeway in Ireland) which were to prove crucial later on.

Regularly stratified rocks and their faults have always been a central theme for geological curiosity. Steno (1638-86), a Dane, was an early worker on this (Italy, 1669). Men began to dream of geological maps, though ordinary ones were still of the crudest.