(1) The trip passes by waterfalls, forests, canyons, valleys, sinkholes and caves.(2) Karst is an area of irregular limestone in which erosion has produced fissures, sinkholes , underground streams, and caverns.(3) The enclosed depressions are complex forms of dolines or sinkholes , which act as centripetal drainage basins.(4) The wells at Chichu00e9n Itzu00e1 are actually large limestone sinkholes - known in Spanish as cenotes (underground pools) - and they are one of the singular aspects of the site.(5) This is the process by which rainwater erodes limestone cliffs and creates limestone caves and sinkholes .
