Lloyd - thanks for the link, a lot to digest
MGmirkin - the "Grey Rock" I have called them is slightly misleading I realise, this unique grey is a covering or plating on these special rocks but is only a few mm thick
. Underneath the grey layer it appears to be "normal" limestone. Grey Rocks don't appear to be like a Dike of different material.
I think it is a plating because this image looks like one part has been plated but then again it may have been transformed or the material inside has been transformed and extruded out.
The lines seem to melt into the ground
or have been formed of the ground around it being drawn up (similar to Lichtenberg mountains?). Of course anything else could have happened to them...
I have thought about digging under the lines but there are a couple of spots where you can see into them. The mineral inside looks fairly normal white limestone. It does have "large" crystals for a limestone though.
I am also waiting until, somehow, I can get what I dig up analysed to see if/how different it is.
With the idea that these lines may not be something that happened ages ago, that they might still be "discharging" slowly or part of some sort of active exchange mechanism (the covering appears to show no signs of being eroded or breaking down) I am trying to find a way to take electrical measurements.
There is an interesting geological puzzle involving Malta that might be related to these and other lines. The islands are formed of 5 layers of limestone. The first and the last layers are identical in chemical composition AND fossils...
These Grey Rock lines are found at Pembroke, which is on the Eastern end of the Great Fault line that divides the island of Malta. This escarpment rises sharply out of the ground. Along the Great Fault line there are sections of the "oldest" limestone "exposed" as they say.
Along the fault line escarpment you can also find some larger lines that also look like discharge lines. At the other end is a stunning sandstone syncline.