Sinkhole urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole. Sinkholes tend to occur in karst landscapes. Karst
A Star Is Bored he believes to be another gun (in reality it is HIS gun bent around so that it points at his hindquarters) sticks up through a hole in the ground just behind him! Daffy retracts his gun; the "other" gun does the same. Daffy does this two or three more times before he decides to try a small experiment. He ties a red ribbon around the barrel of his gun, then sticks it into the tree, and looks behind him. The ribbon on the gun in the ground is white with red polka dots, leading Daffy to believe it to be