Happy Birthday, William
Today in Oxfordshire, England, William Smith - the "Father of English Geography" - was born. (I can heartily recommend The Map That Changed the World by the brilliant Simon Winchester.)
Wikipedia summarizes his life's work thus: As he observed the rock layers (or strata) at the pit, he realised that they were arranged in a predictable pattern and that the various strata could always be found in the same relative positions. Additionally, each particular stratum could be identified by the fossils it contained, and the same succession of fossil groups from older to younger rocks could be found in many parts of England. Furthermore, he noticed an easterly dip of the beds of rock- small near the surface (about three degrees) then bigger after the Triassic rocks. This gave Smith a testable hypothesis, which he termed The Principle of Faunal Succession, and he began his search to determine if the relationships between the strata and their characteristics were consistent throughout the country. During subsequent travels, first as a surveyor (appointed by noted engineer John Rennie) for the canal company until 1799 when he was dismissed, and later, he was continually taking samples and mapping the locations of the various strata, and displaying the vertical extent of the strata, and drawing cross-sections and tables of what he saw. This would earn him the name "Strata Smith". As a natural consequence, Smith amassed a large and valuable collection of fossils of the strata he had examined himself from exposures in canals, road and railway cuttings, quarries and escarpments across the country.