High Ranges (above 750m MSL)
The mountainous land (elevation: 750 m to 2500 m above MSL) along the Western Ghats with jutting rocks and loamy soils constitutes the High Ranges. The two districts of Wayanad and Idukki and the eastern parts of the other districts bordering the Western Ghats come under this class. Most of the reserve forests of the state are in this tract. The important peaks in the Western Ghats are Anamudi (2690 m), Mukunti (2550m) and Nilgiris (2470m). The Palakkad gap with a width of 32 km is the largest pass in the Western Ghats. In addition, there are a few other passes in the Ghats such as Aramboli, kumali, kambam, Thevaram,Bodinaikannuur, karkken, periya and Perambadi. Plantations of tea, coffee, rubber and cardamom dominate the High Range region.
High land (75-750m above MSL)
This hilly tract on the western side of Western Ghats, comprising about 43 per cent of the land and supporting 14 per cent of the population, is covered with forests and small streams. Plantations of tea, coffee, cardamom and rubber are common. The soils are generally forest loams, which show wide variation in depth with a very high percentage of organic matter. A large percentage of the population of hill tribes lives in this region.
Midland (7.5-75m above MSL)
The midland plains comprising about 42 per cent of the land mass have an undulating terrain intersected by numerous rivers, small hills and valley and 59 per cent of the state's population live in this tract. The soil is mainly laterite and supports an intense diversity of seasonal, annual and perennial crops like rice, sugarcane, tapioca banana, ginger, coconut, arecanut, pepper, cashew, rubber etc.
Lowland (Up to 7.5m above MSL)
The lowland bordering the Arabian Sea is a strip of land running along the coast. This region comprises about 10 per cent of the total area, supports 26 per cent of the population and is characterized by marine landforms consisting of beach ridges and beaches with swamps and lagoons. During monsoons, several places are liable to be flooded, particularly 'Kuttanad' area which is situated below the sea level. This region is noted for its picturesque backwaters with extensive paddy fields interspersed with plantation of coconut and arecanut. The soil is generally sandy to sandy loam but alluvial along the banks of rivers.