It's pumped up sand from seafloor, and now that nearby sand is tapped out
                                
                                
                                    (Newser) -
                                    Sand may seem like an infinite natural resource, but as cities with beaches around the world know all too well, it's anything but. And Miami Beach, Fla., is standing at a crossroads now that it, along with the US Army Corps of Engineers, has spent years pumping up sand...