Here's why:

* Laterization: The humid climate and high rainfall in the Western Ghats leads to intense leaching of nutrients and minerals from the soil. This process, called laterization, leaves behind iron and aluminum oxides, which give the soil its distinctive reddish-brown color.

* Formation: Lateritic soils are formed from the weathering of crystalline and metamorphic rocks, which are abundant in the Western Ghats.

* Characteristics: Lateritic soils are typically:

* Poor in nutrients: Due to leaching, they lack essential plant nutrients like nitrogen, phosphorus, and potassium.

* Acidic: They have a low pH.

* Porous and well-drained: The high iron and aluminum content makes them porous, allowing for good drainage.

* Hard and compact: They can be difficult to work with, especially when dry.

While lateritic soils are the predominant type in the Piedmont zone, you might also find pockets of other soil types depending on the specific location within the zone.