Rescue workers in Tampa, Florida have called off their search for Jeff Bush, 36, who is presumed dead after a sinkhole opened under his house and swallowed his bedroom on February 28. Local authorities say Bush’s home will be demolished. Two neighbouring houses have been evacuated for fear the hole may be growing. Hillsborough County Administrator Mike Merrill said, “The sinkhole is very large. It’s a huge chasm, extending down 50-60 feet. With all the equipment we’ve brought in, and specialist help, we’ve just not been able to locate Mr. Bush, and so for that the rescue effort has been discontinued.” The phenomenon is believed to be caused by progressive corrosion of porous, acidic ground. As rainwater filters through the soil it dissolves the rock beneath – creating underground caverns, which cause sinkholes when they collapse.