ABSTRACT
SINKHOLES These are all forms of closed surface depression with drainage sinking underground; also known as dolines, and ubiquitous in karst terrains. Different types have different implications for engineering activity. Solution sinkholes develop slowly like blind valleys; slow rates of formation create no subsidence threat. Collapse sinkholes are not common, and events of rock failure are rare. Collapse processes contribute to forming many sinkholes; over geological time, they can create zones of broken unstable ground in limestone. Buried sinkholes provide potential differential settlement over compacting fill. Conical, cylindrical or irregular; isolated or clustered; 1-50 m deep, 1-200 m wide. Effectively represent an extreme form of rockhead relief with short buried valleys.
