DEVONIAN PERIOD

Table 4: Geologic time scale. To see more information about a period, select one from the chart. interval of the Paleozoic Era that follows the Silurian and precedes the Carboniferous. It is thought to have covered the span of time between about 408 and 360 million years ago (see Table). The Devonian is often divided into the Early Devonian Epoch (408 to 387 million years ago), Middle Devonian Epoch (387 to 374 million years ago), and Late Devonian Epoch (374 to 360 million years ago). The rocks that were formed or deposited during this interval make up the Devonian System. Rocks of this system are known on all continents both at outcrop and in the subsurface. Extensive areas of North America, South America, Europe, and the Soviet Union are underlain by Devonian rocks at depth. Subsequent folding has made such rocks common in many of the ancient fold belts.