Abstract
Many of the national parks in East Africa are equally as famous for their iconic landforms as they are for their diversity and concentrations of fauna and flora. The newly formed Ngorongoro-Lengai Geopark in northern Tanzania is the first geopark to be established in the region, but there is remarkable potential for geotourism in the majority of the national parks. The most spectacular landforms have been shaped by the East African Rift System. Formation of the two major rifts in the region, the Albertine Rift (or western branch) and the Gregory Rift (or eastern branch), was accompanied, or in some cases preceded, by extensive alkaline volcanism. The rifting and volcanism are primarily Late Cenozoic phenomenon that dissected and overprinted the older regional plateaus. Rifting impacted the regional drainage and captured major rivers, including the Victoria Nile. Chains of ribbon lakes formed in the rift valleys. The Albertine Rift consists of a sequence of sedimentary basins with deep freshwater lakes, but the shallow soda lakes of the Gregory Rift are associated with mostly volcanic terrains. Plateau-style volcanic outpourings smoothed out the older land surfaces, created near-lunar landscapes in parts of the rift valley, and built up rift shoulders to tremendous elevations. Magma erupted from central conduits formed giant stratovolcanoes which reveal evidence of explosive, Plinian-style volcanic activity. East Africa includes some of the largest and best preserved calderas on Earth. The Ngorongoro Caldera is a world heritage site. The ice-capped peaks of the two largest volcanoes in the region, Kilimanjaro and Mount Kenya, are among the highest free-standing mountains on Earth. The region includes active volcanoes, several of which are potentially hazardous as they are located near urban centres. Examples include Longonot-Hells Gate (Kenya), Mount Meru (Tanzania) and Nyiragongo (Democratic Republic of Congo). East Africa is renowned for the unusual rapidity of Darwinian evolution during the past thirty million years, including evolution of primates and hominins, and it is not a coincidence that significant palaeoanthropological discoveries have been unearthed from the Oldupai Gorge and Laetoli sites in northern Tanzania. The evolutionary period coincides with the onset and persistence of rifting and volcanism. Speciation is following an island-style pattern in East Africa, despite the continental setting, as regional plateaus are being dissected by the ongoing rifting and volcanism into smaller and smaller geological terrains. This is illustrated by restriction of the endangered Mountain gorilla to regions where afromontane forests developed in rift-related uplands isolated by extensive savannah grasslands.
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