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Speleogenesis question

PostPosted: Sep 19, 2007 7:32 am
by stefan

I'm not shure this is thr right place to post this question but i'll give it a try.

We're exploring and studying a vertical cave in Romania for some time now and we came upon some features that we don't know for shure how they were formed. We searched the web and browsed trough books but .. nothing.

Here is the thing :

The cave has several passages that look like the one in the attached photo. They can be found at the base of almost all the shafts. I hope my drawings are good enough. They look like a ramp tilt at an angle that varies between 20 and 25 degrees. The ramp is separated in two in the middle.

We know that they were formed by water coming down the shafts but we can't figure out a relationship between the volume of water, the height of the shafts and the genesis of these ramps.

What kind of watter flow would it take to form something like this ?
Can someone explain how exactly can something like this be formed ?

Did any of you come across anything similar ?

P.S. Sorry for spelling and grammar errors :D


PostPosted: Sep 19, 2007 9:17 am
by Dwight Livingston
Seems like an interesting question. Unfortunately, I find your drawing is tough to understand. First, the two views are not aligned, so I don't know which end of the Top View corresponds to what side of the section view. Second, the hatching of one view does not seem to correspond to the hatch of the other. If the hatching of the Top View indicates empty space, then it seems the wrong size, but if the hatching of the Top View indicates the formation, then where are the passage walls? As to the Profile section, it might be important to see what happens to the wall of the pit below the formation.

It would help to 1) draw a section line through the plan view to the section to see where the section is cut; 2) use hatching consistantly; and 3) draw all the walls.

So, is the formation a slab-like thing with a notch cut in it, or a more rod-like projection hanging above the lower pit?



PostPosted: Sep 19, 2007 9:36 am
by stefan
You are right, the drawing is no good (I made it in a hurry using mspaint at work, but it made sense to me :) ). I'll make a better one and post it.
The hatched part of the plan view is the floor and the corresponding hatch in the profile of the gallery shows the positioning of the tilted floor and the depth of it. Anyway i'll make a new drawing...

The formation looks like the floor was tilted and a notch cut in it.

Thanks for your interest,

PostPosted: Sep 19, 2007 9:25 pm
by fuzzy-hair-man
I might not understand your drawing either but I though what you might be describing is what I call a rimstone pool or rimstone dams or gours the bottom of which has sprung a leak and been re-disolved or eroded causing the hole in the bottom.

PostPosted: Sep 21, 2007 10:18 am
by stefan

I'm back with a new drawing. I spent a little more time drawing this one so that you can figure out the situation. So, the red area is the area of interest. This area is at the bottom of a shaft. The shaft starts with a section like the brown one shown.
As you can see in the red area we have the start of another shaft. You can go down this one only by climbing to the two slopes, because the space between them is to narrow. The corresponding red dotted figure in the section view represents a vertical section trough one of the slopes.

It is clear to me that the slopes were formed by water sitting at the bottom of the shaft and corroding away the limestone. While making the cut longer the small puddle of water standing at the bottom of the shaft would get smaller and the surface corroded to. In this way step by step the slopes were formed.

The thing I'm not sure about is the amount of water that came down the shaft at that time - the water flow that created the gap ... Was it just a film of water that accumulated slowly at the bottom of the shaft before going further ? Or was it a strong water flow ?



PostPosted: Dec 11, 2007 4:36 pm
I think I can visualize that fairly well now, I have no definite comment or expertise in these realms. I will say it is a good thing you European cavers invented rebelay techniques because this would be an ovious rope trapper.