Enlisted personnel are identified by way of their various 'E' grades ranging from E-1 to E-9. For those service branches recognizing a Warrant Officer rank, 'W' grades range from W-1 to W-5. Likewise Officers are scaled from O-1 to O-10.
China has quite a collection of natural bridges, including one that experts say has the longest span of any natural bridge in the world. The Fairy Bridge (Xianren Qiao), in southwestern China's Guangxi Zhuang Autonomous Region near the border with Vietnam, has a 400-foot span.
Postcard of Arch Rock in 1898. Arch Rock is a geologic formation on Mackinac Island in Michigan. It is a natural limestone arch formed during the Nipissing post-glacial period, a period of high Lake Huron levels following the end of the Wisconsin glaciation. To this day Arch Rock stands on the Lake Huron shoreline 146 feet (45 m) above the water. Limestone breccia is not an ideal material for natural bridges, and this type of formation is quite rare in the North American Great Lakes region.