Patch and repair in large old stone wall?

[Flospel]

On our property line, there is an older (and tall, in some places 4 meters from the ground) stone wall that has lost stones in places. It doesn't appear to be dry stone built. I don't assess that there's an imminent risk of collapse, but small stones are loose in places. How would you proceed to both reduce the risk of future collapse and make the damaged areas less unsightly?

Anyone with experience with this type of wall...? Will it work to slap on cement mortar (or something else?) in the areas where stones have fallen off?

I've marked in red the areas where stones have come loose!

 

[Victor Akerlund]

On our property boundary, there is an older (and high, in some places 4 meters from the ground) stone wall that has partially lost stones. It doesn't seem to be dry-stacked. I don't assess that there is an imminent risk of collapse, but small stones are partially loose. How would you reduce the risk of future collapse and make the damaged areas less unsightly?

Anyone with experience of this type of wall...? Will it work to slap on cement mortar (or something else?) in spots where stones have come loose?

I have highlighted areas where stones have come loose!

Hi, unfortunately, I can't contribute an answer, but I have essentially the same question. Up to a 4m high wall that seems to be constructed in a similar way to yours, where old mortar has deteriorated and smaller stones have started to come loose.

In my case, there is a level difference so behind the wall at the top is my garden. Below the wall runs a road. I'm a bit afraid that the pressure from the masses is pushing out larger stones so that the entire wall over time risks collapsing?

Attached are some pictures.
Grateful for tips and advice on how this can be repaired!

Some pictures show the entire wall, others how it looks inside where larger stones have fallen out.