Fossil fish on mountains puzzled Greeks first
Geology studies Earth’s origin, history, and structure. Xenophanes noted fossil fish and shells on mountains in 540 BC; Herodotus echoed them about 490 BC. Aristotle watched slow change; Theophrastus’s On Stones catalogued ores from Laurium; Pliny later traced amber to tree resin via trapped insects.
Al-Biruni (973–1048) wrote early geology of India and guessed the subcontinent was once sea—medieval science extending Greek curiosity.
Origin-of-Earth debates and mineral handbooks, not field mapping, dominated antiquity. Practical mines and gem lore fed natural philosophy long before “geology” named a profession.
Medieval scholars pushed further. The Persian polymath Ibn Sina (Avicenna, 981–1037) folded geology into his encyclopedic Kitab al-Shifa, and in Song China Shen Kuo (1031–1095) built one of the first theories of landform change from what he saw of sediments lifted up, soil worn away and silt laid down. Only in the seventeenth century did geology emerge as its own branch of natural science, spurred partly by efforts to reconcile Earth's history with the biblical Flood. In his Principia of 1687, Isaac Newton made the first experimental estimate of Earth's age, reasoning from an Earth-sized iron ball cooling down, and arrived at 50,000 years. Speculation of this kind nevertheless sharpened the systematic identification of strata, the horizontal rock layers of roughly uniform make-up.
Eighteenth-century mining booms made knowledge of ores economically valuable, and the Earth's age became dinner-table controversy. The French naturalist Buffon's Histoire Naturelle of 1749 and Immanuel Kant's Universal Natural History of 1755 both described Earth's past without appeal to God or scripture. The word geology entered technical use through two writers from Geneva, and the subject slowly won a place in universities. By the 1770s chemistry had split the field into rival camps over how rock layers formed. One side credited a great watery flood; the other, championed before 1750 by the Abbé Anton Moro after studying volcanic islands and later developed by James Hutton, argued that heat had built the strata.
Source: History of geology
