animation courtesy of http://ucmp.berkeley.edu/geology/anim11.html
Map courtesy of James Wittke at http://vishnu.glg.nau.edu/people/jhw/GLG101/Tectonics.html
Folding in Cornwall
The Caledonides Mountain Range
This is an explanation of the massive Caledonides (also called the Appalachian-Caledonides) mountain range. The Caledonides are the ancient and formerly impressive mountain range that stretched from the Appalachians in North America, through the Atlantic plates, to Scandinavia. They are a remnant of a former age, the result of continental drift, and through exploration of the mineral makeup and geologic history of the mountains, a fascinating picture of a past world takes shape.
The Caledonides is the impressively long mountain belt that is part of the visible evidence of the assembly of the supercontinent of Pangea. The time span is thought to be primarily from the Ordovician through Silurian periods, and the remains can be found in the British Isles, Norwegian and East Greenland, North Greenland, and the Taconic and Acadian phases of the Appalachians.
The dominant geological process contributing to the present location of the Caledonian range is plate tectonics. The now worn range was created roughly 300 million years ago as landmasses collided in uplift during the formation of the supercontinent Pangea. The landmasses involved include Laurentia; the continent composed of North America and Greenland, Baltica; the continent composed of Northern Europe, Gondwana Land; which included South America and Africa, and Iapetus; which is the ocean closed during the collision of plates that formed the Caledonides.
Beginning roughly 200 million years ago, divergent boundaries opened up to create the Atlantic Ocean, disconnecting the once continuous mountain range. The founding premise of modern geology- that the processes that operate today are the same as those of the past- help to create a view of the Himalayas of what these ancient peaks looked like, and subsequently hypothesize as to what the Himalayas may look like in 200 million years.
Products of the Geologic Process
Remnants of the Caledonides can be found through the east coast of North America, notably in the form of the Appalachian mountain, through Newfoundland in Canada, Northern and Southern Ireland, and Scandinavia.
The rock terrane that was a direct result of the Caledonian orogeny has been worn down extensively but can still be found as base for much of the above mentioned regions. The subduction that caused the closing of the Iapetus resulted in igneous activity and metamorphism that left such distinct features as folding, deformation, and thrusts.
The understanding of the history of the Caledonides has most significantly furthered the evidence for continental drift and twentieth century theories about the formation of the earth's crust. Substantially, the Caledonides are of worldwide importance to the crucial development of key concepts in structural geology.
The completed view of the original mountain range has both broadened geologists understanding of the geologic timescale, and supported existing hypothesis' about continental change. This, along with the staggering size and continuity of the former range, are what marks the Caledonides relevance to modern views of natural history.
Author: Beirne Roose-Snyder
Creation/revision date: 26 March, 2002
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This website is part of a Geology 211 class project on Processes in Physical Geology.
Copyright ©-2001 Earlham College. Revised 25 February 2002. Send corrections or comments to firstname.lastname@example.org