Figure 3. Schematic diagram showing stages of development of a coalesced, collapsed-paleocave system. Multiple cave-system development at a composite unconformity may be necessary in order to produce a high density of passages. As the multiple-episode cave system subsides into the deeper subsurface, wall and ceiling rocks adjoining open passages collapse and form breccias that radiate out from the passage and intersect with fractures from other collapsed passages and older breccias within the system. The collapsed-paleocave systems are prime exploration targets. Modified from Loucks (1999).