ScienceNow: For a few months in history, world domination depended on a bridge built upon sand. To conquer the almost impenetrable island of Tyre in 332 B.C.E., Alexander the Great had his engineers construct a land bridge across a kilometer of open water. Given that his army had only basic tools and was under constant attack, the feat seems almost miraculous. But was it? After analyzing the past 10,000 years of coastal sediment deposits, a team of researchers concludes that Mother Nature--not the renowned Greek military commander--was the primary bridge builder.