The very morphology (shape) of this passage is characteristic of caves formed along faults which are virtually all tall and linear. The Middle Cave entrance is located in the fault and is the highest point in the cave system, over 100 ft above the entrance to Hansen Cave. The Middle Cave fault is a "normal" fault, meaning that it is formed by tensional (pulling apart) rather than compressional (pushing together) forces. In normal faulting the "head wall" moves down and the "foot wall" moves up. When you are in a fault cave the "head wall" is the rock over your head while the "foot wall" is the rock under your feet. Middle Cave fault records about nine feet of vertical displacement (slip) between the head and footwalls. Although, that doesn't sound like a lot of movement it is important to remember that in some places normal faulting can displace rock beds by miles.

Near the end of this passage, if you look way up, part of an old wooden ladder is visible in the darkness. This ladder was used by surveyors in the 1930's, to enter this part of the cave, when they were blasting the tunnels. Definitely not a feat for the feint- hearted!

Visitors must now pass through a very narrow, tall passage which follows the Middle Cave fault line. These pictures look up toward the ceiling of the cave showing direct evidence of the fault itself.