Paleozoic Era: Stratigraphy

You can find out more about the Paleozoic by clicking on the chart below!

A favorite exercise in introductory paleontology courses is to invent mnemonics for the periods of the Paleozoic. These mnemonics all stand for the seven time periods into which the Paleozoic is divided: Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian. Note that European geologists lump the Mississippian and Pennsylvanian into a single time period, the Carboniferous.

Most of these names derive from locations where rocks of these ages were first studied. Cambria was the Latin name for Wales, and the Ordovices and Silures were two Welsh Celtic tribes. The Devonian is named for Devonshire, England. The Mississippian is named for the upper Mississippi River valley, NOT the state of Mississippi, which has very few rocks of this age. The Pennsylvanian is named for Pennsylvania, surprisingly enough, while the Permian was described from rocks in the region of Perm, a town in the Ural Mountains of Russia. The exception to this rule is the Carboniferous Period; its name means "coal-bearing," and this period is in fact the time when extensive coal beds were formed around the world.

Find out more about the Paleozoic paleontology and geology of North America at the Paleontology Portal.