The northwest part of Kenya has three main geographic zones running in parallel north to south. There is the highland plateau, which rises gradually to 3,350 meters above sea level, on the Cherangani Hills. In the intermediate zone is the Elgeyo Escarpment which rapidly gives way to the lower Kerio Valley. The yearly rainfall in the escarpment area ranges between 100–140 cm.
- Shacleton, Robert Millner (1950). "A contribution to the geology of the Kavirondon Rift Valley". Quarterly Journal of the Geological Society. 106: 345. doi:10.1144/GSL.JGS.1950.106.01-04.18.
- Julius Muchemi, Wangu Mwangi & Heinz Greijn. "GIS in support of participatory land use planning in the Districts Keiyo & Marakwet, Kenya". www.gisdevelopment.net. Retrieved 2008-03-16.