The surface is quite flat - it was inside what would have been a dwelling at one time. The trough you can see is not a groove as the 'wall' is perfectly smooth.
I was not intending to give a detailed analysis with the post, more a layman's version, as most members come to the site from a biological perpective as you will have noticed.
I understand what you are saying, but even so, the formation here is highly debateable.
Thanks for your comments,
Desert Abstract - False Bedding Planes (56) *