Hi Joanna. This is a unique structure. What is the main rock type of the dome? Is it carbonate or silicate? What kind of minerals that fill these fractures? These domical fractures seemes to be almost equally spaced. Please can you provide more information about the history of this area? It seems to me like a wall !!!!!!!!

It looks like someone went bonkers with a drill. Is this an old quarry?

They seem drillings; probably the rock has been drilled to produce equally spaced holes along a line to detach a big portion.

vertical fractures are drillings for sure and they not interesting, I'm focused on these domical fractures. They are visible in whole quarry but they they limited to almost one very thick-bed. @Richard here is another photo from this part of quarry.

Hy.

I know this kind of structure very well. It appears in various kind of hard rocks. In France, we call them "Baraminoceras"...

The result of a short drilling in a quarry in order to detach a block or tu put explosives inside. In French, a "barre à mine" is the tool used in the past to manually drill such holes.

I hope it was a joke...

Thanks Richard I for any hint :) I will looking further... The Research Gate not allows to put more pictures than one in one comment this is the reason why I put them so slow, but I have more photos of these structures. @Patrick as I wrote I focused not on "Baraminoceras" as you nice explained :) but this strange domical convex structures/fractures/cracks - or what it is. Here is another photo from the opposite wall of the quarry.

I guess this structure due to surface pressure decline.

The photos indicate the fractures are related to post-depositional processes. Others here suggested they are exfoliation features, but that seems improbable since the fractures are concentrated in one bedding unit. You need to focus on the sedimentary structures present within this bedding unit to determine if porewater migration, and hence cementation, was controlled by variability in clast size or variability in cement composition and/or structure. For instance, might these be dunes that formed in an area where the water table was fluctuating between the peak and trough of the "domes"? If so, then you'd see this in the clast size and sedimentary structure (i.e. crossbedding). If the unit appears massive (i.e. no discernible sedimentary structures), then cement will likely have variability in composition and/or texture. For instance, porewater migration may have been laterally of vertically limited, leading to localized cementation within flow channels.

Thank You, I will follow this idea.

A few of us seem to be concerned about the drill scars - these are the result of either "pre-splitting" or "feathering" to break the rock - but Joanna is not interested in these. The domed structure is unusual but it appears (in the first image at least, that the original primary sedimentary fabric is horizontal and not disturbed. That being the case I thnk this is a product of "Core - stone" weathering. One point just needing confirmation - can you confirm the way -up? The fisrt image appears more "normal" upside down.

If it is a genuine domed structure I would supspect some form of carbonate bioherm - any fossils apparent?

To me all three photographs could be pseudonodules or cycloids similar to the flame type structure of Dzulynski and Walton (1965), and ball-and-pillow

structure of Potter and Pettijohn (1963), or pseudonodules

of Hempton and Dewey (1983).

Maybe these references can help

Dzulynski, S.,Walton, E.K., 1965. Sedimentary Features in Flysch and Greywackes. Developments in Sedimentology, vol. 7. Elsevier, Amsterdam. 274 pp.

Potter, P.E., Pettijohn, F.J., 1963. Palaeocurrents and Basin Analysis. Springer, Berlin. 296 pp.

Hempton, M.R., Dewey, J.F., 1983. Earthquake induced deformational structure in young lacustrine sediments: East Anatolian Fault, Southeast Turkey. Tectonophysics 98, T7–T14.

Singh, S. and Jain, A.K., 2007. Liquefaction and fluidization of lacustrine deposits from Lahaul-Spiti and Ladakh Himalaya: geological evidences of paleoseismicity along active fault zone. Sedimentary Geology, 196, 47-57.

I am not suggesting that they are Earthquake induced structure rather they are sedimentary structures.

First of all, I am happy to have a discussion with my former student!

You have found something really interesting, in my opinion. You were very perceptive to observe these structures. I agree with Daniel - they might be diagenetic features like concretions, but giant ones and coalesced. The domical line might be parting between concretions (below) and the host rock (above). They do not stick out of the wall, as usually concretions do, because this is not a natural outcrop. In fact mechanical and chemical properties of concretions and surrounding rocks are sometimes very similar anyway. You can see this paper:

http://onlinelibrary.wiley.com/doi/10.1111/sed.12098/abstract

where we described calcite concretions in calcite-cemented graywackes that only differ in calcite content, being somewhat higher in the concretions. You need to compare mineralogy/petrography of the rock below and the rock above the domical line. Good luck!

the is because of a pre-splitting  blasting