Bauxite and Hematite Cappings in the Nilgiris, Tamil Nadu-Study from Geomorphic Angle

The Nilgiri plateau is marked by a number of bauxite and hematite cappings, the former over charnockites and the latter over magnetite quartzite, as products of residual chemical weathering. A study of disposition in space of about twenty groups of bauxite and six groups of hematite cappings indicates their Occurrence confined around 8000' and 7000' above M.S.L. and these conform to two surfaces already reported on geomorphic evidences.

In the absence of datable sediments overlying the cappings, it has not been possible to find the exact age of the laterites. Based on a general finding from worldwide occurrences of bauxite that gibbsite forms first and later transforms over a period of geological time into boehmite and diaspore, it is inferred that the Nilgiri bauxites could be of Tertiary age.