laterite

noun

1. (countable, uncountable)A red hard or gravel-like soil or subsoil formed in the tropics that has been leached of soluble minerals leaving insoluble iron and aluminium oxides and hydroxides; used to make bricks and roads.

   “Although the track is ballasted, it does not prevent clouds of reddish dust from the laterite soil blowing about when the train is in motion; after a journey with the windows open a bath is a necessity!”

   “Constant tropical rain makes a mush of hard old lavas. The end product is a brick red soil called laterite.”