strange mortar damage, 100 year old house

[John Arnold]

Anyone familiar with this type of damage?

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[Jerry Peck]

Hard to tell what I'm looking at, but what I think I am looking at is mortar spanning extra wide openings (to big to call them "joints"). In doing, the masons left air pockets behind the mortar and, for whatever reasons, the mortar bridging over the air spaces has either been knocked in or has come loose and is falling out.

[John Arnold]

Jerry, Thanks. You gave me an idea for wording, anyway.
What you're looking at is pretty typical of many older homes in Philadelphia. The stone and mortar, I mean, not the holes.

[Lon Henderson]

Hmmmm, one of the holes looks like it's in the stone. Another looks chipped around the edge. Is this all the holes or is the wall covered in these holes? If this is all, it looks like someone chipped them out with a chisel. If these kind of holes cover the wall, then it's probably, something else

[John Arnold]

Hmmmm, one of the holes looks like it's in the stone. Another looks chipped around the edge. Is this all the holes or is the wall covered in these holes? If this is all, it looks like someone chipped them out with a chisel. If these kind of holes cover the wall, then it's probably, something else

No, the picture is just an example. It's more like all over the front of the 3 story rowhouse.

[Jerry Peck]

I first looked at that on my phone, now on my computer (the bigger screen makes a big difference) ... but my reply would be the same, except that now I can see the air pockets and air space behind the thin mortar used to fill between the stones.

The raised white lines are, I think, supposed to 'look like" "mortar joints" with the brown mortar used to fill the gaps between the stones being used to make it look like the stones were not too small or were not spaced too far apart, or both.

Over time, settlement and other movement will cause/allow the thinner and not adhered mortar areas to crack out, especially if in a freeze/thaw area.

[Mark Reinmiller]

Anyone familiar with this type of damage?

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The stone looks like Wissahickon Scheist. It often deteriorates and is patched with mortar. The holes may be random areas where stone was exposed after patching, but later deteriorated.