© Robert E. Gentet 2015
James Hutton (1726-1797) is the one most credited with overthrowing a belief in a young Earth. It was once commonly taught and believed that fossils and rock formations were the result of the great Flood described in Genesis. However, as geologic data accumulated, it became harder and harder to correlate the findings with a singular event such as the Flood.
Nicolaus Steno (1631-1687) properly identified fossils as belonging to once-living organism and more importantly came to understand how sediments form when they accumulate in horizontal layers in bodies of water (the bottom-layer being older than the one on top). Steno invoked other cataclysms besides the Flood to explain the Earth's geology.
Robert Hooke (1635-1703) advocated violent upheavals in the Earth's past that would uplift buried sediments under the sea and form land. Like Steno, Hooke still held to a young Earth.
Leibnitz (1646-1716) also saw the need to acknowledge that more than the Flood waters of Noah formed the earth's strata. He said the initial waters that covered the Earth in Creation Week were the source of many strata.
Benoit de Maillet (1656-1738) was the first to estimate an ancient Earth perhaps as old as two billion years. This was based upon the dubious idea that a universal ocean covering the entire Earth would take that long to recede into "vortices." He also believed "seeds" found throughout the universe accounted for life on Earth. Interestingly, some scientists today are speculating that life came to the Earth on a comet or other source from Outer Space.
By Hutton's time, there was already a ripe atmosphere for new ideas on the origin of the Earth's strata and life forms. Hutton filled this void by invoking very slow natural processes. Hutton resided from 1754 to 1767 on his farm in Berwickshire, Scotland. Here, instead of watching the sea, he looked at the slow erosion of his farmland. He assumed all sedimentary rocks are the result of erosion and all the Earth's surface is being eroded. The slow erosion he observed would take enormous amount of time to account for the thick layers of sediment worldwide. Thus, a very ancient age of the Earth became his conclusion. This began what is termed uniformitarianism. It dominated geological thinking due to the works of Charles Lyell who popularized Hutton's thoughts. This original form of uniformitarianism, only slightly modified, dominated mainline geological thinking until the early 1960s. Since then, episodes of catastrophic events are included in geologic time. But, it is thought, most of geologic time is relatively quiet.