The visual aspects of a rammed earth wall differ distinctively from any other wall . Rammed earth is compressed, rammed, in a steel frame when it is slightly moist. The horizontal lines which are then to be seen in the surface resemble the layers in the earth that appear over many years. The material and its appearance create the idea of an earth-linked structure, built geology. As a base material a 'rich' type of earth is needed, in which there should be a part stones, a material that could resemble concrete in grading of particles. As few types of earth will lend themselves for ramming as they are found, often sand andstones are added. Just as with clay plaster, it is possible to add colors to the rammed earth. In this way coloured horizontal lines are created