Earth Geology Geologic Time Scale Cambrian Period

Cambrian Period

The Cambrian time period lasted from 544 to 505 million years ago, a time span of 39 million years. The Cambrian is the first or oldest period of the Paleozoic Era. The term Cambrian was first used in the 1830s to describe a sequence of rocks in Wales. The name Cambrian was the ancient name for Wales. These Cambrian rocks were defined based on a particular type of fossil assemblage contained within them. They are located above the rocks of the Precambrian System and below the rocks of the Ordovician System.