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4 - The Americas

Published online by Cambridge University Press:  05 June 2012

E. M. Bridges
Affiliation:
University of Wales, Swansea
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Summary

The Americas consist of fragments of the former continents of Laurasia and Gondwana, rifted apart in the late Mesozoic and moved westwards away from Europe and Africa. The two separate lithospheric plates of North and South America only became linked together in the late Cretaceous by the orogenic activity which produced the Central American mountain chains (Figure 4.1). Thus, the Americas fall naturally into three parts and it is convenient to discuss their geomorphology under the headings of North, Central and South America.

Information about landforms in the Americas is uneven in amount. Much less research has been done and little has been written about Central and South America compared with North America. This disparity is reflected in the text which follows.

NORTH AMERICA

The work of American geomorphologists has made the geomorphology of North America widely known, and examples from North America have illustrated geomorphological textbooks to the exclusion of comparable examples from other parts of the world. The area of North America is approximately 21.5 million km2, and includes the countries of Canada, USA, Mexico and Greenland. It extends from 25°N latitude to beyond 80°N (over 6000 km) and from longitude 60°W to 170°W, although the main part of the USA lies between 70°W and 125°W, a distance of 4200 km.

The eastern margin of the North American lithospheric plate is a constructive margin, the mid-Atlantic ridge, extending from approximately 20°N to the Azores and then to Iceland.

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World Geomorphology , pp. 66 - 118
Publisher: Cambridge University Press
Print publication year: 1990

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  • The Americas
  • E. M. Bridges, University of Wales, Swansea
  • Book: World Geomorphology
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9781139170154.005
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  • The Americas
  • E. M. Bridges, University of Wales, Swansea
  • Book: World Geomorphology
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9781139170154.005
Available formats
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To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • The Americas
  • E. M. Bridges, University of Wales, Swansea
  • Book: World Geomorphology
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9781139170154.005
Available formats
×