* O Horizon: This is the top layer, composed of organic matter like leaves, twigs, and decomposing plant and animal material.

* A Horizon: This is the topsoil layer, rich in minerals and nutrients due to the decomposition of organic matter from the O horizon. It's usually darker in color than the layers below.

* B Horizon: This is the subsoil layer, which is usually richer in clay than the A horizon and may have accumulated minerals leached from the layers above.

It's important to note that not all soils have all three horizons, and the exact composition and appearance of each horizon can vary greatly depending on the soil type, climate, and other factors.