The quartz grains of sand are hard and do not absorb water. Sand, therefore, as a component of soil, plays a crucial role in keeping the soil aerated. Clay is made up of minerals like calcium carbonate, quartz, and oxides of aluminum and iron. The particles tend to be very fine-grained and pack together densely. Pure clay is a poor base for plant growth and is often all that is left after richer, humous soil is stripped away by erosion.
Silt is a general term for sediment washed away by running water.
Silts found in soils may be a mixture of sand, clay and other mineral particles. Anywhere soil is found, it has the same structure. His students gather around him at the edge of a pit, about 1.5 meters deep. You can lift off the underlying mineral soil, like you'd lift off a carpet from the living room floor. But it's not always like a piece of carpet.