1.   Intermittent drainage, underground watercourses and vast cave systems are features of the karst.

2.   Another cave system, Ozark Caverns, is within its boundaries, and naturalists present summer programs in an open-air pavilion.

3.   From China to Europe, elaborate cave systems that have provided shelter to those on the run are not uncommon.

4.   He said he did not have information confirming reports that bin Laden had personally emerged from the cave system to lead his troops.

5.   Rumsfeld acknowledged the difficulty of locating and penetrating cave systems, deep in the mountains of Afghanistan, that are multilayered, sophisticated and self-sustaining.

6.   Stretching through the southwestern corner of the state, Mammoth Cave is a series of chambers and passageways on five different levels that connect to two other cave systems.

7.   The discovery in the deepest part of Sterkfontein, a cave system northwest of Johannesburg, was made by Witwatersrand University palaeo-anthropologists Ron Clarke and Phillip Tobias.