Jenolan Caves

Underground Karst Features

We learn about the way caves were formed by looking at the shape of caves and of bedrock solution features in them. Major features found in caves are described below.


Bellholes are small domes, which have developed in the roof of caves. They are often found rising above the level of flat epiphreatic roofs, though the specific process that forms them is still debated.


Breakdown is rubble produced by the collapse of cave roofs. The floor of the Exhibition Chamber in the Lucas Cave is made of breakdown. Breakdown often occurs in cones associated with cave sediments.

Channel Incuts

Channel incuts are curved, roughly horizontal, indentations, in the wall of vadose passages.  They are produced by successively lower stream levels.


Flutes are elongate, vertical, current markings, found on cave walls. They are produced by water flowing at a velocity higher than that which forms scallops.

Pressure Tubes

Pressure tubes are phreatic cave passages, with circular or elliptical cross-sections.

Roof Pendants

Roof pendants are unusual-shaped pieces of rock that project from cave roofs. They are remnants of rock left behind by solution. Many have the form of blades, and are wedge-shaped, with their thin side pointing towards the direction of flow.


Scallops are hollows in cave walls, produced by the flow of turbulent water. They can be used to indicate the direction of flow when they were formed.


Spongework is where the rock has been dissolved away in three dimensions, to leave behind bedrock that looks like a sponge or Swiss cheese. Roof pendants, blades, and rock bridges are common features of spongework.

Wall and Ceiling Pockets

Wall and ceiling pockets are curved depressions in cave walls and ceilings. They are the result of solution taking place in three dimensions, in a cave filled with water. Wall and ceiling pockets develop as a result of solution in still, phreatic (nothephreatic) conditions.

Vadose Canyons

Vadose canyons are deep, narrow cave passages produced by cave streams, as they cut down through limestone. Vadose canyons often have channel incuts, and they frequently meander.

 A good example of flutes.

This is a great example of a roof pendant.

 This image shows perfect examples of scallops.  The hand shows their size.

 This blade is a type of spongework.

 This is a good example of a wall pocket, caused by solution in still conditions.









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