One hundred seventy-three sinkholes have been reported since 1665, but most (80%) reported sinkholes postdate 1965.
Sinkhole dimensions provided information on the type of collapse. Seven large sinkholes, displacing a total sediment volume of 480,000 m3, resulted from large-scale roof breakdown after pillar failure. The smaller sinkholes were the result of fall of the overburden into galleries after local roof collapse or suffosion of a solution pipe.