Cᵉ siècle av. J.-C.
Sub-Saharan Africa
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The African planation surfaces are extensive erosion surfaces formed during prolonged phases of stability after regional uplift. The most widespread, known as the African surface, mid-Tertiary surface, or Miocene peneplain, consists characteristically of flat grassland or bushland interrupted by residual inselbergs. Later Miocene and Pliocene uplift caused renewed river incision and produced post-African or end-Tertiary valley-floor surfaces.
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Le récit
Long intervals of stability following uplift allowed erosion to flatten broad areas of sub-Saharan Africa. The most extensive surface is variously called the African surface, the mid-Tertiary surface, or the Miocene peneplain. It is typically represented by flat grassland or bushy terrain, with resistant remnants surviving above it as blocks or inselbergs.
In East Africa, Miocene lavas and fossiliferous sediments accumulated on an erosion surface often termed the sub-Miocene surface. Subsequent Miocene uplift rejuvenated drainage and caused rivers to incise and dissect the older surface. The resulting landscape included younger, less extensive surfaces known as post-African or end-Tertiary surfaces.
During the Pliocene, further uplift intensified river incision. Headward erosion remained especially important, so valleys widened only slowly while upper streams continued to flow across older planation surfaces. These surfaces provide a useful regional framework, but their ages are not uniform, making correlations between different parts of Africa uncertain.
The extract associates widespread uplift since the Cretaceous with major changes in African relief and climate. In sub-Saharan Africa, the total uplift may have reached roughly 900 to 1,200 metres, with about half occurring since the middle Tertiary. Differential warping complicates the estimate and limits confidence in simple continent-wide correlations.
Cᵉ siècle av. J.-C.
Sub-Saharan Africa
Traduction non disponible · Original (anglais) · français indisponible
The African planation surfaces are extensive erosion surfaces formed during prolonged phases of stability after regional uplift. The most widespread, known as the African surface, mid-Tertiary surface, or Miocene peneplain, consists characteristically of flat grassland or bushland interrupted by residual inselbergs. Later Miocene and Pliocene uplift caused renewed river incision and produced post-African or end-Tertiary valley-floor surfaces.
Poursuivre l’exploration
Le récit
Long intervals of stability following uplift allowed erosion to flatten broad areas of sub-Saharan Africa. The most extensive surface is variously called the African surface, the mid-Tertiary surface, or the Miocene peneplain. It is typically represented by flat grassland or bushy terrain, with resistant remnants surviving above it as blocks or inselbergs.
In East Africa, Miocene lavas and fossiliferous sediments accumulated on an erosion surface often termed the sub-Miocene surface. Subsequent Miocene uplift rejuvenated drainage and caused rivers to incise and dissect the older surface. The resulting landscape included younger, less extensive surfaces known as post-African or end-Tertiary surfaces.
During the Pliocene, further uplift intensified river incision. Headward erosion remained especially important, so valleys widened only slowly while upper streams continued to flow across older planation surfaces. These surfaces provide a useful regional framework, but their ages are not uniform, making correlations between different parts of Africa uncertain.
The extract associates widespread uplift since the Cretaceous with major changes in African relief and climate. In sub-Saharan Africa, the total uplift may have reached roughly 900 to 1,200 metres, with about half occurring since the middle Tertiary. Differential warping complicates the estimate and limits confidence in simple continent-wide correlations.