Where a wall stops, it has to stop properly. The hill wall comes to an end at the rocky shoulder near the top of the slope, and that end is built differently from the rest. It is called a wall head, and it is something like a column built into the end of the wall: the stones at the very end are laid in long and short courses, one going across the end and the next running back into the wall, so that the corner is bound in both directions. It is the hardest part of a wall to build well, and wallers often save their best stones for it.
The other end, behind the doghouse, does not have a wall head. There the wall simply runs into the slope, getting lower as the ground rises around it, until the top stones are almost at the level of the grass and then disappear into it. It is hard to say exactly where it begins. That is common with old walls. They often start and end in places where the land made it unnecessary to build any further.
In between, along the line, there are a few small features. Near the spring, there is an opening at the foot of the wall, a square hole about a foot across with a flat stone over it, to let the water through instead of letting it build up behind the wall. A little farther up, there is a place where a few flat stones stick out from the face, one above the other, like a short ladder; this is called a stile, and it was built so that people could climb over without knocking the copes off. Higher still, where the path bends, there is a gap in the wall that was never filled, wide enough for a cart, with tall stones on either side where a gate once hung.
These are the kinds of things that make one wall different from another. The method of building is nearly the same everywhere: footings, faces, hearting, throughs, cover band, copes. But the stone is different in every place, and so are the slopes, the weather, the old purposes, and the people who did the building. Two wallers given the same gap and the same pile of stone will not build exactly the same thing, though both of their walls will stand.
When the gapping is finished, it is easy to see where it was done for the first few months. The new work is cleaner than the old, with sharp edges and no moss, and the stones have a slightly different color where their faces were turned to the inside for many years. Over the next couple of winters this fades. The rain and the frost get at the new stone, and the lichens start to come back, and the mended stretch begins to look like the rest of the wall.