Horizon

soil isn't dirt. it's a layered history that decides what a state grows.

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

Every soil is a stack of horizons — a surface layer of decayed organic matter, a topsoil where roots feed, a subsoil where minerals collect, and the broken parent rock underneath. What varies from place to place is what filled that stack: silt from a flooding river, weathered volcanic rock that swells and cracks, iron-stained bedrock, or monsoon rain that has leached one soil for millennia. That history is why one state grows cotton and its neighbour grows millets — the ground itself is a record, not a blank surface.

Concepts: geology, ecology.

An interactive you play with one thumb, on Wundr.