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.
Most Roman triumphal arches were built during the imperial period. By the fourth century AD there were 36 such arches in Rome, of which three have survived-the Arch of Titus (AD 81), the Arch of Septimius Severus (203-205) and the Arch of Constantine (312). Numerous arches were built elsewhere in the Roman Empire.