Horizon

dig six soils. read what each one grows.

drag a spade along the ground — dig six Indian soils and read what each grows

Every soil is a stack of horizons: decayed matter on top, topsoil where roots feed, subsoil where minerals collect, rock beneath. What differs is what filled the stack, why one place grows cotton and another millets.

Concepts: geology, ecology.

An interactive you play with one thumb, on Wundr.