Help required: Analysing the city walls. Main gateway to Dura Europos

            The walls are made from a sedimentary rock, described as crystalline gypsum. This block intrigued me because it shows a localised depression of the layers above a hole. (I am assuming that the block was laid in the wall the same way up as it was when it formed in the ground!)
I can only surmise that as the original sediments were hardening, a foreign body (e.g. a harder piece of rock such as a meteorite) landed on it, deforming the partially solidified layers, and penetrated this far.
The upper sediments were insuffieciently elastic to flow back over the foreign body afterwards but the depression was filled in by subsequent deposition of the normal sediments.
When the stonemason cut the block from the quarry, over 2000 years ago, he must have hit the foreign body and dislodged it. The fact that this "imperfect" block was still used in the construction of the main gateway to the city is also interesting. Did the builders appreciate its unusual form?
ANY OTHER IDEAS WOULD BE APPRECIATED!
   

Taken in: سوريا / دير الزور / As salihiyah (show map)

Taken on: October 9, 2010

Tags:

Syria

Syrie

Siria

SYJ

Doura Europos

Dura Europos

As Salihiye

Geology

gypsum

impact

layers

strata « less

Sets appears in: • Syria • Geology and Geomorphology

Groups appears in: • Geology Rockers • Geologists

Camera: Canon PowerShot SX120 IS, f/4.0, 1/100 sec, 28.1mm, ISO 100 (more info) (hide info)

Camera:	Canon PowerShot SX120 IS
Aperture:	f/4.0
Exposure Time:	0.01 sec (1/100)
Focal Length:	28.1mm
ISO:	100
Exposure Bias:	0 EV
Flash:	Off, Did not fire
Exposure Mode:	Auto
Metering Mode:	Multi-segment
White Balance:	Manual
Color Space:	sRGB
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