International "Old Rock Day"

History of “Old Rock Day”

The study of rocks was first introduced by the Ancient Greek Theophrastus in his work, “Peri Lithon” (“On Stones”), and became the cornerstone of geology for other interested scientists. The study was advanced by Pliny the Elder, who recorded numerous minerals and metals in great detail, with a particular focus on their practical use. Although working without the tools we use today, Pliny was able to correctly identify the origin of amber as fossilized tree resin.

It wasn’t until 1603 when the word ‘geology’ was used for the first time by Italian naturalist Ulisse Aldrovandi. It took a further 150 years for the first geological maps to be drawn by British geologist William Smith, whose work began the process of ordering rock layers by examining the fossils contained in them.

Then, in 1785, James Hutton wrote and presented a paper to the Royal Society of Edinburgh called ‘Theory of the Earth’, which outlined his belief that the world was far older than previously thought. His breakthroughs make him widely considered the first modern geologist.

In 1809 William Maclure produced the first geological map of the USA, a task he completed thanks to two painstaking years spent personally traversing the country. With the invention of radiometric dating in the early 20th century, scientists could finally provide an accurate figure for the age of the earth by tracing the radioactive impurities found in rocks. It helped scientists to see that the Earth is one very old rock indeed!

Rocks have been essential for human development, which is why we celebrate Old Rock Day and the wonder of the geological world.