There are thousands of different soils around the world, but their basic makeup consists of sand, silt, clay, or a combination of any or all of these. Sand tends to quickly drain water and silt has intermediate drainage properties. Clay soil holds onto water better than sand or silt, which is why it is known as an expansive soil. Expansive clay soil can be found throughout the country, and it is prevalent in areas of Colorado including Denver, Colorado Springs, and Grand Junction.