Course of the Colorado River into the Virgin River, which ran southward through what is now Overton Arm to join the Colorado River near the now-ghost town of St. Thomas, Nevada. At Hoover Dam, the Colorado turns due south through Black Canyon, a direction it will follow for the remainder of its course to the Gulf of California. It passes under the Mike O'Callaghan–Pat Tillman Memorial Bridge (Hoover Dam Bypass), the highest concrete arch bridge in the world, carrying U.S. Route 93 at a height of above the Colorado River. At the end of Black Canyon the Colorado widens into Lake Mohave, created by the
Black Rock Dam (Schuylkill River) crossings of the Schuylkill River Black Rock Dam (Schuylkill River) The Black Rock Dam is a low head dam in the Schuylkill River. Originally constructed as a stone filled, timber crib dam in the early 19th century by the Schuylkill Navigation Company, the dam was one of dozens built to create a slack water pools for the Schuylkill Navigation System. The dam is a contributing property of the "Schuylkill Navigation Canal, Oakes Reach Section" registered historic district. The dam is located between Phoenixville and Mont Clare in southeastern Pennsylvania, USA. The original dam structure is "L" shaped. There is the