In China, the polymath Shen Kuo (1031–1095) formulated a hypothesis for the process of land formation: based on his observation of fossil animal shells in a geological stratum in a mountain hundreds of miles from the ocean, he inferred that the land was formed by erosion of the mountains and by deposition of silt.
Nicolas Steno (1638–1686) is credited with the law of superposition, the principle of original horizontality, and the principle of lateral continuity: three defining principles of stratigraphy.
It is publicly important for the prediction and understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change.
Geology plays a role in geotechnical engineering and is a major academic discipline.
Estimates varied from a few 100,000 to billions of years.
By the early 20th century, radiometric dating allowed the Earth's age to be estimated at two billion years.
The first shows the entire time from the formation of the Earth to the present, but this compresses the most recent eon.William Smith (1769–1839) drew some of the first geological maps and began the process of ordering rock strata (layers) by examining the fossils contained in them.James Hutton is often viewed as the first modern geologist.Hutton published a two-volume version of his ideas in 1795 ( Vol. Sir Charles Lyell first published his famous book, Principles of Geology, in 1830.The book, which influenced the thought of Charles Darwin, successfully promoted the doctrine of uniformitarianism.This theory states that slow geological processes have occurred throughout the Earth's history and are still occurring today.