Quaternary glaciations in the East African mountains

Abstract

This chapter reviews that the three highest east African mountains, Kilimanjaro, Kenya, and Rwenzori, all over 5000m, still carry small but rapidly diminishing glaciers, have conspicuous Last Glacial Maximum (LGM) moraines and have some evidence of several extensive former glaciations. Two lower mountains of about 4000m, Elgon and Aberdare, have probably LGM moraines but no current glaciers, and evidence of only one glaciation. There is no reliable evidence of glaciation neither on Mount Meru nor on the Virunga volcanoes. The chapter also discusses a full account of Mount Kenya for comparative purposes of some data. The similar Ethiopian mountains are also described in the chapter. All these mountains are equatorial, with moderate to high annual precipitations, though on some this is sharply reduced at the highest levels. On the five high East African mountains that were glaciated at the LGM, the glacial extents and estimated equilibrium line altitudes (ELAs) at different times show remarkable differences and similarities between the mountains and between different aspects of each mountain. The areal extent of the LGM glaciers on the three highest mountains is in inverse order to their summit altitudes, reflecting partly their form and partly their humidity regime: the highest and driest, Kilimanjaro, has the smallest glaciated area. It also reviews that, at the LGM, the local equilibrium line altitudes (ELA) on the outliers was far below that on the main peaks and that the depression in ELA must either be assessed separately on the main and minor peaks or preferably by taking into account the form of the ELA profile or trend surface.