This photo was taken looking down what D terms. “The overflow shelf”. At the last open crevice before our cave tunnel disappears completely there is a big pile of organic debris. It blocks what appears to be the logical progression of the water down a tube shaped passage deeper and deeper into the earth.
A small tunnel drains to this spot. There is also a large (human sized) tube and some kind of surface flow that must run during a rainstorm or snow melt. In all the crevice receives water from three separate sources and for this reason one might imagine that the tunnels from here onward would be larger than those that preceeded them. Unfortunatly the downstream passage is blocked by a plug of organic matter; it is not possible to see a tunnel beneath the debris. Some digging will be required.
Things likely drained quite well until the land nearby was cleared. This would have upset the flow patterns that had facilitated cave development here. Water runs from a bare field in great muddy torrents, dragging with it sand, mud and gravel. Conversely, a forest holds a great deal of water and then releases it slowly. The debris that blocks the tunnel is likely a result of the land’s clearance some 100 – 150 years ago.
What you are seeing to the left of the photo is a log wedged into the overflow shelf. It would appear that as the floodwater pools at the organic plug, backing up and filling the crevice from whence it churns forward along this shelf. The shelf leads onward to a sizeable joint some 8 feet inwards. I suspect that the tunnels below also meet the joint and from there the water is likely ferried downward to some impervious layer deeper down.
From the underside of this log a progression of fungal shoots sprout upward. In the absence of sunlight photosynthesis is not possible and so by way of bat’s guano or flood-deposited organic debris, fungus grows and forms the basis of the cave food pyramid. Tiny glistening bugs the size of pinheads swarm up the shoots, no doubt a symbiosis of some type exists.
The decaying log is an important part of the cave food system. With so few imputs this type of water-washed debris is a source of both nutrient and energy in the underworld. As it decays the fungus and bacteria harvest their life’s requirements from it. Its chemicals are passed up through the food chain though the amount of energy is constantly diminishing. (lost to heat and movement). Cave dwellers are especially efficient in their movements and habits. Unlike the chemicals, the energy is not recycled.