The Moon does have a layer of loose material on its surface, but it is not dirt or gravel as we know it on Earth. The lunar regolith is a layer of fine, dusty material that covers most of the Moon's surface. It is composed of broken rock and dust created by impacts of meteoroids, asteroids, and comets over billions of years. The regolith is very fine-grained, with particles that range in size from dust to small rocks. It is also very dark in color, due to the presence of iron and other heavy elements.