Abstract
THE recent report by Girdler et al.1 on the rift system of East Africa is of great interest because it presents a crustal model, based on new gravity observations, which suggests an intrusion of low velocity mantle material rising to the base of the sialic crust which underlies the eastern and western rift valleys of East Africa between 3° N and 9° S over an east–west width of about 1,000 km. The crustal model proposed is thus in a general way comparable with the postulated to underlie the worldwide mid-ocean ridge2 and the Upper Rhinegraben3. Studies of seismicity, age of faulting, age of volcanoes and short and long wavelength gravity anomalies are interpreted by the authors as indicating attenuation of the African crustal plate and the early stages of its breakup. The structural behaviour of East Africa is compared with the conveyor belt mechanism of sea floor spreading from mid-ocean ridges as recently reviewed by Vine4 and rates of movement away from the rift axis of 0.5–2.0 cm yr−1 are said to be indicated.
Similar content being viewed by others
Article PDF
References
Girdler, R. W., Fairhead, J. D., Searle, R. C., and Sowerbutts, W. T. C., Nature, 224, 1178 (1969).
Talwani, M., Le Pichon, X., and Ewing, M., J. Geophys. Res., 70 341 (1965).
Illies, J. H., Tectonophysics, 8, 5 (1969).
Vine, F. J., Proc. Amer. Phil. Soc., 112, 325 (1968).
Walker, G. P. L., Phil. Trans. Roy. Soc., A, 258, 199 (1965).
Baker, B. H., UMC/UNESCO Seminar on East African Rift System Nairobi, 2, 1 (1965).
Mason, P., Geol. Surv. Kenya Rep., 31 (1955).
Pulfrey, W., Geol. Surv. Kenya Bull. (second ed. revised by Walsh, J.), 9 (1969).
Holmes, A., Principles of Physical Geology (Thomas Nelson, London, 1965).
McConnell, R. B., Geol. Soc. Amer. Bull., 80, 1775 (1969).
McConnell, R. B., Masson Smith, D., and Berrangé, J. P., Geol. en Mijnb., 48, 189 (1969).
Cratchley, C. R., and Jones, G. P., Overseas Geol. Surv. Geophys., Div. Pap. No. 1 (1965).
Bullard, E., Everett, J. E., and Smith, A. G., Phil. Trans. Roy. Soc., A, 258, 41 (1965).
McConnell, R. B., Nature, 215, 578 (1967).
Baker, B. H., Nature, 224, 359 (1969).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
MCCONNELL, R. Evolution of Rifting in Africa. Nature 227, 699 (1970). https://doi.org/10.1038/227699a0
Received:
Issue Date:
DOI: https://doi.org/10.1038/227699a0
Comments
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.