The geology, geomorphology and soils of the Kulubi area,rnin eastern Ethiopia, are described.rnThe succession of rocks in the region comprises Precambrianrnrocks consisting of gneisses, granites, and raigraatit - es overlainrnby a trachyte flow; Lower Sandstone Unit (Triassic to LowerrnJurassic) consisting of a lov/er arenaceous and an upper calca-^rnreous sub-units; Limestone Unit (Lower Jurassic to Middle-Cretaceous)rnconsisting of sandy and fossiliferous carbonate rocks;rnUpper Sandstone Unit (Middle Cretaceous) consisting of a crossbedded,rnparallel-bedded, calcareous, and massive and laminatedrnsub-units with Mesozoic volcanic intercalations; Tertiary basaltsrnand Quaternary sediments.,rnThe three stages in the geomorphological evolution of thernarea include a Late Cretaceous-early Cenozoic peneplatation;rnTrappean tectonics and formation of basin-plains; and renewedrnerosion associated with the rift tectonics*rnThe major soils in the region are Vertisols, Entisols, andrnMollisols.rnThe Vertisols occupy depressions in alluvial plains andrnscattered spots on Hie'uplands and are developed on basalt andrnalluvium. They are ddep, clayey soils with low chromas andrnvalues. Chemically, they are very slightly alkaline, very lowrnto medium- .in organic matter, low in total nitrogen, and veryrnlow to low in phosphorous. These are the least productivernsoils.The Entisols occur on alluvium and on steep slopes of basalts,rnsandstones and gneisses.rnrrnThey are dark grayish and reddish brown, shallow and discontinuous,rnloamy soils. They are slightly acid to very slightlyrnalkaline, low to medium in organic matter and total nitrogen,rnand medium to high in phosphorous. Their occurrencernon either actively eroding or flooding surfaces significantlyrnreduces their agricultural productivity.rnThe Idollisols are the dominant soils occupying flat torngentle slopes on all theparent materials excepting the basalt.rnThose are brownish-blaclc and reddish-brown, shallow to deep,rnclay, clay loam, and sandy clay loam soils. They are stronglyrnacid to slightly alkaline. The organic matter and availablernphosphorous contents differ widely. They have a low to mediumrntotal nitrogen. These are the most productive soils.rnComparison of these soils in terms of their textures, pHs,rnand organic-matter contents indicates that topography is thernmain soil-forming factor controlling the morphological, physical,rnand chemical properties of these soils.