Marks on the blocks of the Grand Gallery

[Jon101 180]

Hi, I hope you are all well.

I happened upon a picture of the GP Grand Gallery.

I see there are 'J',(or reversed 'L'), shaped striations on some of the blocks lower edges. I presume they might be rope or cutting marks. Can anyone tell me what they are?.

My Google must be having an off day as I can't find mention of them.

Thanks, as ever, to all replies.

Edit: There are far better pictures than this, but they are too large to upload.

Edited November 27, 2020 by Jon101
Adding stuff.

[Thanos5150 587]

They are metal braces installed in modern times to shore up cracking. 

[Jon101 180]

Thank you, I actually thought they looked like braces or brackets of some kind, but then I dismissed it as a trick of the light.

Really appreciate that you took the time to reply.

[Thanos5150 587]

7 hours ago, Jon101 said:

Thank you, I actually thought they looked like braces or brackets of some kind, but then I dismissed it as a trick of the light.

Really appreciate that you took the time to reply.

No worries.