Heat created in this chamber (or in a firebox close by) is contained there and so builds up to high temperatures. The ceramic ware undergoes the firing and cooling process. While clay can be fired in an open fire and does not require a kiln, kilns must be used to attain high temperatures.
The Colorado Plateau, a series of flat lands, gorges, mountains and valleys, extends south into Arizona, and covers most of northern half of the state. The Black Mesa, Painted Desert, and Monument Valley in northeastern Arizona are some of the plateau's most interesting areas. Scattered tree-covered ranges of the Rocky Mountains wind through the Plateau, including the Black, San Francisco and White Mountains. Humphreys Peak is the highest point at 12,633 ft.
The point where Utah, Colorado, New Mexico, and Arizona meet is called  Four Corners and is unique among the states. Arizona base map, Courtesy of Maps.com. This elevation map of Arizona illustrates the number of feet or meters the state rises above sea level. The lowest areas of the state are along the Colorado River where a low point of 70 feet above sea level is reached. The highest point in Arizona is in the northern part of the state.