The Amazonis quadrangle is of great interest to scientists because it contains a big part of a formation, called the Medusae Fossae Formation. It is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. The surface of the formation has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them and demonstrate the erosive power of Martian winds. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Using a global climate model, a group of researchers headed by Laura Kerber found that the Medusae Fossae Formation could have easily been formed from ash from the volcanoes Apollinaris Mons, Arsia Mons, and possibly Pavonis Mons. Another evidence for a fine-grained composition is that the area gives almost no radar return. For this reason it has been called a stealth region. Layers are seen in parts of the formation. Images from spacecraft show that they have different degrees of hardness probably because of significant variations in the physical properties, composition, particle size, and/or cementation. Very few impact craters are visible throughout the area so the surface is relatively young. Researchers found that nearly all the dust in that coats everything and is in the atmosphere has its origin in the Medusae Fossae formation. It turns out that the chemical elements (sulfur and chlorine) in this formation, in the atmosphere, and covering the surface are the same. The amount of dust on Mars is sufficient to form a 2 to 12 meters thick layer over the entire planet. Since there are relatively few depositional features in the Medusae Fossae Formation, most of the materials being eroded are probably small enough to be suspended in the atmosphere and transported long distances.