The formation of gypsum karst collapse-column and its hydrogeological significance

There are widely distributed collapse-columns in the Carboniferous and Permian rocks in North China. Since 1944, geologists and hydrogeologists have generally considered the collapse-columns as the products of collapsed limestone karst caves of Ordovician 1),2),[1]. In 1960, the author made a postulation that the collapsecolumns are gypsum karst features [2]. In this article, the author gives a detailed account of this view.