A view at the tunnel floor near the ventilation shaft – note the circular spot on the floor. This is probably made by rain mixing with the inches thick layer of bat guano – although it did smell as if another excretory liquid from our mammalian cousins contributed to the sticky, wet floor directly below the ventilation. As usual, one can spot the bats by the ‘headlamps’ staring back at you. The black dots you probably see in the crown of the tunnel end are the flying bats. Inside the tunnel, short stones mark the permanent way on either side. Often, these stones are hidden under the clay and it is all too easy to trip on them and end up with a mouth full of guano - or worse, get intimate with a dead bat. As mentioned before, our torches are just not adequate to light up the tunnel and all these details and fine thoughts were possible only after seeing the pics on the computer screen.
We believe that the tunnel roof slopes up towards the ventilation shaft (that is located in the center of the tunnel) to encourage a natural flow of the smoke.