What's in a Wall?

St Paul’s church at Peel, Little Hulton has a very large graveyard containing some magnificent memorials. Running alongside the right hand side of the building are a large number of small headstones which are closely packed. They are for cremated remains. It works well until a portion of the supporting wall collapses, tipping headstones and cremains [an awful word] over the edge. Worse still, it provides an opportunity to discover what the retaining wall is constructed from . . . Sorry, but I just don’t like it and I keep coming across path kerbs and walls made of the same thing!