<human>:  What are the different types of soil and how do they form?
<bot>: There are three main types of soil: sand, silt, and clay. Sand has the largest particles and clay the smallest, with silt falling in the middle. These different particle sizes are the result of how each type of soil is formed. Sand is mostly the result of rocks and minerals such as quartz, feldspar, and mica being eroded away by wind and water over a long period of time. Silt is formed when sand particles are split further by water and wind erosion, creating finer particles. Clay soil comes from the weathering of rocks and minerals, and the breaking down of them into their smaller particles.