In one caving trip some time ago we stumbled upon a small cave that was (and still is :) ) filled with sediments. The gallery shape indicates that it was an exurgence. The gallery slope is around 35 degrees and when we first found it, it was filled to the ceiling after the first 5 meters in length and around 2 meters in depth. After a few digging trips we managed to move forward about another 5 meters and approx. 2 meters in depth. The sediments removed were: a thick layer of dry clay followed by some gravel and small stones mixed with a moister clay. The gallery slope is constant and seems that it will go on like this for a while.
I tried to figure out how did this cave get filled up with sediments but I didn't come to any conclusion. The presence of the small gravel could be explained by the fact that the cave was an exurgence and it transported this material but it seems to be quite high on the slope. Moving on to the thick layer of dry clay that fills the rest of the gallery up to the ceiling, I can't explain how it got there. I don't think it could have been transported by water because the lower parts of the gallery would become filled to the ceiling first thus obstructing the transport from that point up. I first thought that the filling came from outside the cave but I also ruled out this option since the deposits were to compact to me organic material from the surface (we found no air pockets). Another possibility that the clay could have infiltrated from the surface with rain water in the course of many thousands of years.
I am not an expert in cave sedimentation and until now I found no relevant material to fit this specific case. So if anyone has an idea on how sedimentation occurs in this kind of settings or can point me to a helpful resource it would be great.
Here is also a picture of the cave entrance to give an idea on how steep the slope is: http://www.speotimis.ro/galerie/Cheile-Garlistei-oct-2009/noua-pestera.jpg
Thanks in advance!