Based on the texture, colour, depth and chemical composition soil has different layers.
∙ Uppermost layer is top soil which is soft and porous. It is rich in humus.
∙ Second layer is subsoil which is hard and compact. It is rich in minerals.
∙ Third layer is parent rock which is made of lumps of rocks with cracks and crevices.
∙ Last layer is bedrock which is the hardest layer. It is very difficult to dig this layer with a spade.