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
Tiny (Once Upon a Time) Anton concludes that all humans are liars and resumes his attacks. David offers to surrender himself if Anton will spare everyone else. When Anton leaps towards David, he crashes through the ground into a sinkhole just as the mushroom wears off, leaving him human-sized and clinging to a pipe. David leads the townspeople in rescuing a despondent Anton from the pit, restoring his faith in humans. Anton is welcomed by the townspeople. He reveals the beanstalk stems and is brought to fertile farmland where he could grow beans, making it possible to return to the Enchanted Forest. He warns that