Devonian


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Devonian

Geology of, denoting, or formed in the fourth period of the Palaeozoic era, between the Silurian and Carboniferous periods, lasting 60–70 million years during which amphibians first appeared

Devonian

[di′vō·nē·ən]
(geology)
The fourth period of the Paleozoic Era, covering the geological time span between about 412 and 354 × 106 years before present.
References in periodicals archive ?
Trewin and Davidson (1996) considered that Pterygotus anglicus found in Early Devonian rocks of the Midland Valley of Scotland spent their whole life in fresh water.
Waters said that as plant communities expanded onto land to form the first forests, they depleted the carbon dioxide (CO2) that was in the atmosphere, asserting that CO2 levels dropped to 400 ppm toward the end of the Devonian.
Only 16 species, commonly represented by single specimens, of Silurian and Devonian scorpions were recognised in 15 genera by Jeram (1998).
This outcrop was mapped as Upper Devonian Ohio Shale by Reidel (1975) and lies stratigraphically above (immediately downstream of) a Middle Silurian dolostone.
Medium-crystalline, often cavernous dolomitic rocks occur only in the basal part of the Devonian section.
The young Paleozoic stage consists of Devonian rocks, which discordantly overlie the Silurian rocks.
Records at these sites suggested that the Late Devonian saw a prolonged drop in echinoderm diversity consistent with a mass extinction.
Keywords: Devonian, New Harmony Group, subsurface Indiana
Two outside operated Devonian wells in the neighboring section have combined to produce 350 MBO and 3.
Boundary intervals of chronostratigraphic units are always significant for correlation purposes, and the Middle--Upper Devonian boundary is no exception.