The Paleocontinent Euramerica
Euramerica (sometimes referred to as Laurussia) was formed during the Silurian with the joining of two earlier continents, Laurentia (cratonic North America) and Baltica (European Russia, Scandinavia, parts of Central Europe and most of the British Isles). Most of the Euramerican landmass (northeast Canada, Greenland and most of Baltica) has often been referred to as the "Old Red Sandstone Continent".
There are two major competing recontructions of the Paleozoic continents. They both broadly agree with respect to the shape, orientation and equatorial position of Euramerica. However, they differ dramatically in the positions and orientations of Gondwana (including South America, Africa, India, Southern Europe, Antarctica and Australia). For example, Dalziel et. al. (1994) propose a Gondwana in which central Africa lies at the South Pole and northwestern South America obliquely collides with eastern North America. The Gondwana proposed by Scotese and McKerrow (1990) doesn't lie as far south and the areas closest to Euramerica include northwest Africa and southwest Europe. A more recent investigation by Streel et. al. (2000) based on palynomorph distributions indicated that Euramerica was located at a slightly lower latitude than is generally accepted in the above reconstructions.
Reconstructions of paleocontinents prior to the breakup of Pangea (beginning in the Triassic) are substantially more difficult than reconstructions for the Mesozoic and Cenozoic. Radioisotopic the rocks formed via sea-floor spreading is the most reliable method of positioning continents, but there are no substantial sea-beds older than the Triassic. Consequently, scientists must rely on paleomagnetism, similarities of geologic formations and fossil organisms among continents. Paleomagnetism only yields paleolatitudes and the readings can be conflicting, while similarities in organisms and geological formations are subject to multiple interpretations. It shouldn't be surprising that the reconstructions differ.
The Acadian Orogeny is a salient geologic feature of Euramerica during the Devonian. It started during the Middle Devonian and was centered in New England and the Maritime Provinces of eastern Canada. It apparently extended southwest to Alabama by the Late Devonian or Early Carboniferous. Explanations for the cause of the Acadian Orogeny vary, but most theories involve some form of continental collision. In any case, these once impressive mountains have since been greatly reduced by erosion; vestiges are still visible in New England and Canada, but the southern extent lies under the modern-day Atlantic Coastal Plain.
Donald Woodrow has generated a series of climatic models for the Devonian. Although the results are subject to a number of qualifications, they indicate that latitudinal temperature gradients were modest (i.e., differences between polar and tropic temperatures were not as great as they are today). There are also indications that the Catskill Delta received strongly seasonal rainfall. A strong seasonality in rainfall is corroborated by the presence of vertisols at Red Hill.
- National Park Service (US) web page on Devonian paleogeography:
- Palaeos.com's web page on Euramerica:
- Paleoportal.org's web page on Devonian paleogeography:
- Christopher R. Scotese's reconstruction of the Middle Devonian paleogeography and Late Devonian Climate:
- Scientific Papers:
- Dalziel, I.W.D., L.H. Dalla Salda, and L.M. Gahagan. 1994. "Paleozoic Laurentia-Gondwana interaction and the origin of the Appalachian-Andean Mountain systems." Geol. Soc. Amer. Bull. 106:243-252.
- F.R. Ettensohn. 1985. "Controls on develoment of Catskill Delta complex basin-facies." pp. 65-77. In: D.L. Woodrow and W.D. Sevon (eds.). The Catskill Delta. Geological Soc. America Special Paper 201.
- Steel, M, M.V.Caputo, S. Loboziak, & J. H.G.Melo. 2000. "Late Frasnian-Famennian climates based on palynomorph analysis and the question of Late Devonian glaciations." Earth Science Reviews 52:121-173.
- Scotese, C.R. and W.S. Mckerrow. 1990. "Revised world map and introduction." In: W.S. McKerrow and C.R. Scotese (eds.). Paleozoic Paleogeography and Biogeography. Geol Soc. London Memoirs 51: 1-21.
- Woodrow, D.L. 1985. "Paleogeography, paleoclimate, and sedimentary processes of the Late Devonian Catskill Delta." pp. 51-63. In: D.L. Woodrow and W.D. Sevon (eds.). The Catskill Delta. Geological Soc. America Special Paper 201.
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