Mike B</a> wrote:
>The second picture shows nothing of value to this
<img src=" [www.geology.ohio-state.edu] ">
<img src=" [www.viewzone.com] ">
Take a closer look at the sandstone unit in the center of the 1st image (i.e. above the shale), do you not see the joint bounded concentric erosion morphology present there? Other than the size difference these two photos appear somewhat similar to me in their general morphology, and I would think that that should show something of value to this discussion. The 1st photo is an example of spheriodal weathering of a cliff face and it appears to be producing concentric separation bands bounded by joint planes.
>but I am very intrigued by the bottom picture.
>This does indeed show a natural formation that shows
>concentric rings in the rock. You asked whether I think this
>is spherical weathering and I have to say no. I think what
>we are looking at here is something else, but that isn't
If it is not spheriodal weathering than what is it, what geologic mechanism is producing it?
>What is important is the fact that you have shown
>a precedent for the concentric formations. This is obviously
>not manmade, so whether it is spherical weathering is really
>arbitrary. No matter what process caused the formation they
>found we know that there are completely natural examples, so
>unless they can come up with some kind of evidence of
>habitation there appears to be nothing manmade about the
>One final comment I have is: take a close look at the
>details of your first and third picture and tell me what
>differences stick out. There are a couple of them that imply
>that these formations may not be entirely similar.
I am sure there is... no two outcrops ever are the same especially when they are different rock types potentially exposed to different erosion mechanisms.
>In the top picture look at how the tops of those rings have
>sharp edges as opposed to the smooth ones in the bottom pic.
So... they show varying degrees of weathering along the concentric fractures of separation due to erosion...
>Also as you state, the weathering of the "furnace" is still
>controlled by jointing. This will only hold true for a while
>and then the erosion will eat through the side and bottom
>joints as well.
That has not happened yet in the "Phoenician Furnaces" site. just as it has not happened in the sandstone outcrop in the first photo above.
>Both of these facts signify to me that this
>formation became exposed to weathering at a relatively recent
>date. Would you agree or disagree with that?
Yes most of the weathering and erosion appear to be recent in a geological sense.
> You must admit
>that the erosion is not very extensive so far. This also
>eliminates spheroidal weathering as the cause of the rings.
Which ring... the coloured ones or the separations? The coloured ones are the Liesgang rings. The concentric separations would be the spheriodal weathering.
>Keep in mind that I believe it is natural, I just think we
>are looking at a different process.
You will need to present a weathering mechanism that produces concentric separations of the host rock bounded by joint planes.
>> Mike B