Nelson Rock and Mineral Club
The Devonian was a relatively long geological period, lasting from 417 to 354 million years ago. Globally, it was a time of great upheaval, as the two major continents of Euramerica and Gondwanaland drew closer together and the super-continent of Pangea began to form (see Figure 1). The associated tectonic activity gave rise to a number of major mountain zones, including the Appalachians in North America and the Caledonian mountains of northern Britain and Scandinavia. In Europe and North America, which straddled the Equator, arid conditions prevailed, and extensive areas of desert and shallow-water sandstones (the ‘Old Red Sandstone’) were laid down. Nevertheless, during this period, terrestrial life gained a more extensive foothold on land as vascular plants became abundant, and forests developed, while arthropods became widely established. In the seas, fish thrived, with the result that the Devonian has sometimes been called the ‘age of the fish’.