d85ee3fe-c7dd-4fe2-bef9-3e8e37b5c399 urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-10-17T04:55:34 creation ISO 19115 2016 Geological Timescale Bookmark d85ee3fe-c7dd-4fe2-bef9-3e8e37b5c399 A simple geological timescale suitable for printing at A4 size; the one-page version has both sides of the bookmark together. The geological timescale is one of the major achievements of geoscience over the last two centuries. The timescale subdivides the 4.6 billion years since the planet formed into a series of time units (e.g. Jurassic Period). Rocks and particularly the fossils within them have been compared across the world to work out their age relative to each other. This information has been calibrated against an absolute ages of rocks are usually calculated by measuring the natural radioactive decay of minerals. The international standard timescale allows geoscientists to determine the ages of events in Earth history and so understand the evolution of the planet from its formation to the present day. For the most up to date International Chronostratigraphic Chart head to www.stratigraphy.org. Earth Sciences Educational Product Published_External Download the A4 one page print (pdf) [523 KB] documentDigital Download the A4 one page print (pdf) [523 KB] PDF Download the print ready file (pdf) [662 KB] documentDigital Download the print ready file (pdf) [662 KB] PDF Unnamed resource documentDigital HTML