The Dalit Association is extensive with major developments:
in the west coast from Sipitang to Kota Belud,
in the interior plains notably between Keningau, Sook and Dalit and northeast of Ranau,
in the Mananam Plain,
in the Lokan Peneplain adjacent to the Ruku Ruku River,
in the Karamuak, Labuk Tungud and Ruku Ruku valleys, and
in between the Sungai Sugut and the Sungai Kanibongan.
It consists of low hills and alluvial flats with an amplitude of about 60 m at altitudes below 150 m. The hills are convex in shape with slopes ranging from 10-15°, but exceeding this on some incised lower slopes. The alluvial flats are often more than 400 m wide and are dissected by shallow gullies. They are poorly drained and often swampy.
Parent materials comprised interbedded reddish brown sandstone and mudstone on the low hills and mainly coarse-textured alluvium on the flats. In addition, in the Mananam Plain some low hills are composed of medium-textured old alluvium representing terrace remnants.
Lowland dipterocarp forest covers the low hills, except in the Mananam Plain, where large areas are either under shifting cultivation or have reverted to secondary forest following cultivation. Poor forest often with small trees and an undergrowth of sedges occurs on many of the wet alluvial flats.