Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Differential denudation and flexural isostasy in formation of rifted-margin upwarps


MARGINAL upwarps are common features of rifted continental margins1,2, but tectonic models of the evolution of rifted margins have not adequately explained their form, or their persistence along some margins more than 100 Myr after continental rupture. Marginal upwarps not only significantly influence the geomorphological evolution of rifted margins and their adjacent continental interiors, but are also important in determining patterns of offshore sedimentation. Here we show that the contrast in denudation rates between the evolving coastal flanks of rifted margins and their interior hinterlands can promote significant marginal upwarps if the lithosphere responds flexurally to the resulting differential unloading2,3. Using data for the western margin of southern Africa, we demonstrate that upwarps of 600 m with respect to the adjacent continental interior can be generated by this process independently of the mechanics of rifting.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout


  1. Oilier, C. D. (ed.) Z. Geomorph. Suppl. 54 (1985).

  2. Summerfield, M. A. in Tectonic Geomorphology (eds Morisawa, M. & Hack, J. T.) 27–51 (Allen & Unwin, Boston, 1985).

    Google Scholar 

  3. Thomas, M. F. & Summerfield, M. A. in Int. Geomorph. 1985, Proc. 1st Int. Conf. on Geomorphology (eds Gardiner, V. et al.) 935–956 (Wiley, Chichester, 1987).

    Google Scholar 

  4. Buck, W. R. Earth planet. Sci. Lett. 77, 362–372 (1986).

    Article  ADS  Google Scholar 

  5. Buck, W. R., Martinez, F., Steckler, M. S. & Cochran, J. R. Tectonics 7, 213–234 (1988).

    Article  ADS  Google Scholar 

  6. McKenzie, D. P. Nature 307, 616–618 (1984).

    Article  ADS  Google Scholar 

  7. Braun, J. & Beaumont, C. Geology 17, 760–764 (1989).

    Article  ADS  Google Scholar 

  8. Weissel, J. K. & Karner, G. D. J. geophys. Res. 94, 13919–13950 (1989).

    Article  ADS  Google Scholar 

  9. Royden, L. & Keen, C. E. Earth planet. Sci. Lett. 51, 343–361 (1980).

    Article  ADS  Google Scholar 

  10. White, N. & McKenzie, D. P. Geology 16, 250–253 (1988).

    Article  ADS  Google Scholar 

  11. White, R. S. & McKenzie, D. P. J. geophys. Res. 94, 7685–7729 (1989).

    Article  ADS  Google Scholar 

  12. Cox, K. G. Nature 342, 873–877 (1989).

    Article  ADS  Google Scholar 

  13. Bohannon, R. G., Naeser, C. W., Schmidt, D. L. & Zimmermann, R. A. J. geophys. Res. 94, 1683–1701 (1989).

    Article  ADS  Google Scholar 

  14. Rust, D. J. & Summerfield, M. A. Mar. Petrol Geol. (in the press).

  15. Brown, R. W., Rust, D. J., Summerfield, M. A., Gleadow, A. J. W. & De Wit, M. C. J. Nucl. Tracks (in the press).

  16. Moore, M. E., Gleadow, A. J. W. & Lovering, J. F. Earth planet. Sci. Lett. 78, 255–270 (1986).

    Article  ADS  Google Scholar 

  17. Oelofsen, B. W. Geophys. Monogr. 41, 131–138 (1987).

    Google Scholar 

  18. Ahnert, F. Am. J. Sci. 268, 243–263 (1970).

    Article  ADS  Google Scholar 

  19. Gerrard, I. & Smith, G. C. Am. Ass. Petrol. Geol. Mem. 34, 49–74 (1980).

    Google Scholar 

  20. Stephenson, R. Geophys. J. R. astr. Soc. 77, 385–413 (1984).

    Article  ADS  Google Scholar 

  21. Lambeck, K. & Stephenson, R. Aust. J. Earth Sci. 33, 253–270 (1986).

    Article  ADS  Google Scholar 

  22. Moretti, I. & Turcotte, D. L. J. Geodyn. 3, 155–168 (1985).

    Article  Google Scholar 

  23. Culling, W. E. H. J. Geol. 73, 230–254 (1965).

    Article  ADS  Google Scholar 

  24. Nadai, A. Theory of Flow and Fracture of Solids (McGraw-Hill, New York, 1963).

    Google Scholar 

  25. Karner, G. D. & Watts, A. B. J. geophys. Res. 87, 2923–2948 (1982).

    Article  ADS  Google Scholar 

  26. Ebinger, C. J., Bechtel, T. D., Forsyth, D. W. & Bowin, C. O. J. geophys. Res. 94, 2883–2901 (1989).

    Article  ADS  Google Scholar 

  27. Speight, J. G. in The Age of Landforms in Eastern Australia: Tech. Memo. 87/2, 61–65 (CSIRO Div. Water and Land Resources, Canberra, 1987).

  28. Summerfield, M. A. Area 13, 3–8 (1981).

    Google Scholar 

  29. Partidge, T. C. & Maud, R. R. S. Afr. J. Geol. 90, 179–208 (1987).

    Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gilchrist, A., Summerfield, M. Differential denudation and flexural isostasy in formation of rifted-margin upwarps. Nature 346, 739–742 (1990).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing