Lateritization and landscape development in Kyagwe, Uganda

In Kyagwe the ‘high-level’ laterite capped mesas, the remnants of the Buganda Surface, do not belong to a monocyclic land surface. The nature of the ground-water laterite on the sloping summits of the remnants varies altitudinally. Vermiform laterite is followed downslope by spaced and then packed pisolithic laterite. Further downslope the sequence is repeated. Study of the ‘low-level’ ground-water laterites suggests that (1) the pisolithic laterites are immature and form in association with a gently lowering water-table and (2) the vermiform variety is a mature formation associated with a stable water-table. The development of the vermiform laterite of a planation surface is outlined. The ‘high-level’ laterite sequence on the mesas is interpreted as belonging to two erosion cycles. The two laterite profiles, consisting of vermiform overlying spaced pisolithic laterite, have been truncated and reworked to form continuous sheets • The immature spaced pisolithic laterite and mottled zone which underlies the vermiform laterite of a planation surface is believed to form as the water-table commences lowering upon initiation of the succeeding cycle. Each profile is therefore bi-cyclic. The formation of the underlying pallid zone is discussed in terms of a post-incision modification by leaching through the carapace. The two planation surfaces represented by the mesas of the Buganda Surface are discussed in relation to the denudation chronology of Uganda.