A coral reef is made of thin layers of calcium carbonate A coral reef is made of thin layers of calcium carbonate National Ocean Service National Oceanic and Atmospheric Administration U.S. Department of Commerce
Arches is located in northeastern Utah, near the city of Moab. The park is famous for over 2,000 natural stone arches and offers much to the outdoor traveler. There is a 40-mile paved loop tour of the park with numerous trailheads and outlooks.
inï¬ uence of the Roman development of the arch, a supporting structure in. building construction that could carry a lot of weight. An arch is a curved structure that is usually made of stone, brick, concrete, or, more recently, steel. Its purpose is to support or strengthen a building. Most arches consist of wedge-shaped blocks. The top center stone, called the keystone, is the last block to be inserted. During construction, arches are often supported by a wooden frame. When the frame is removed, both sides of the arch press against the keystone and thereby support the arch. The Romans did not invent the arch. Indeed, arches have been used since prehistoric times. The ancient Egyptians, Babylonians, and Greeks all used it. The purpose of the arch in these cultures, however, was limited to