Along the eroding edge of the Southern California coast, nature has reasserted its claim on what humans have long tried to hold. Hurricane Marie's relentless surf carved a 30-by-30-foot sinkhole beneath the driveway of Nicolas Cage's $10.5 million Malibu oceanfront home in the early hours of Tuesday, exposing the structural beams beneath and rupturing a gas line that prompted authorities to red-tag five neighboring properties. The event is less a celebrity curiosity than a warning written in concrete and sand — one that Malibu's officials fear may be only the opening chapter of a punishing coa