The Cambrian is a geologic perio and system that began about 542± 0.3 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004). It was the first period of the Paleozoic era of the Phanerozoic eon. The Cambrian takes its name from Cambria, the classical name for Wales, the area where rocks from this time period were first studied.