Turtle Rock pseudokarst caves, Queensland.

The caves form a set of horizontal, joint-controlled passages that alternate with open joint-fissures at the surface.

Genesis is uncertain: Solution of the ignimbrite? Erosion by seeping water with joint and bedding-plane guidance?

Additional work is needed to determine the exact nature of the host rock (e.g. its porosity), and whether there are differences between the petrology of the beds hosting the caves and those above and below.

Selected photographs and diagrams

Map of the Turtle Rock caves, showing collapsed sections as well as roofed cave.

Diagrammatic cross section of Turtle Rock and Ships Stern, showing geology.

Surface trench in bedded ignimbrite. This trench leads to the largest of the caves (below).

The largest cave - looking out the northern cliff entrance.

Side chamber of the big cave. Note scupltured surfaces, the joint-fissure to left and the main entrance chamber to right.

Entrance to the second cave. This is a smaller, but more complex system of rectilinear joint-controlled passages (see other photos below)

Small passage following a joint in the ignimbrite It almost looks solutional!

Window in cliff, looking out from a joint-controlled passage.