. "Geological time is divided into useful segments that are then further sub-divided. A well known example is the Jurassic, which is a Period, part of the (much longer) Mezosoic Era. The Jurassic Period is sub-divided into the Early, Mid and Late Jurassic Epochs. Some Eras are divided into sub-eras, similarly, Periods, Epochs and Ages can have sub-divisions."@en . . "This schema defines named divisions of geological time."@en . "2011-02-10" . . . "http://data.bgs.ac.uk/ref/Geochronology/Division"@en . "2010-02-12" . . "BGS Geological Time Divisions"@en .