Walking in the Southern Uplands. Ronald Turnbull

      Just above the granite junction on Redstone Rig

      The granite of the Galloway Highlands melted its way up into the standard Southern Upland rock, which is the chunky deep-ocean sandstone called greywacke. Around the edges of the granite the country rock is cooked and crumbled, so all around Mullwarchar and Craignaw lie valleys such as the Silver Flowe. But a mile or two further out, the surrounding greywacke was baked and hardened, and this tougher rock rises in the hill ridges of Merrick and the Kells and Minnigaffs. The result is a ‘metamorphic areole’, also known as 50 miles of fine hill-walking in a ring around the granite heartland.

      The difference between the Merrick’s greywacke and the granite around Loch Enoch is fairly noticeable as you descend Redstone Rig. Dark, uniform grey gives way to paler speckles; layered sandstone gives way to rounded granite. To inspect the actual rock junction, take a leftward line down the ridge and look for a striking slab sloped towards you. The granite–greywacke junction crosses the downhill rockface below (NX 4343 8532).

      Approaching the granite, the heated greywacke loses its bedding structure. On the other side, approaching the magma chamber wall the granite forms only the smallest crystals, so the visible speckles are lost. Thus the difference between the two is less marked at the actual junction than across the hill as a whole.

      Descend south of east, with steep drops into Howe of the Caldron on your left. In clear conditions, once at the plateau edge it is possible to see Loch Enoch spread below; head for its right-hand corner. In mist, the wide, lumpy Redstone Rig provides no clear line – aim somewhat to the left (north) of the loch corner, and on reaching the loch turn right along a sketchy path. The loch’s southwest corner has a fence line running down to a tiny golden-sand beach. Here switch to Walk 6 for the Rig of Buchan descent.

      Continue along the loch’s south side on a sketchy path for 250 metres, then turn up to the right into a grassy gap between two hillocks. At once this becomes a little pass, just 15m higher up than the loch itself. The actual outflow is at the northwest corner, but here, and also the northeast and southeast corners, are almost outflows too.

      A peaty path forms in the little pass and leads down just west of south, with a small stream on its left, to reach the reed-infested western corner of Loch Neldricken, known as the Murder Hole.

      Like Doone valley on Exmoor, the Murder Hole is a fictional place that has made it onto modern maps. In The Raiders by SR Crockett, the evil Macaterick bandits murdered passing hill-walkers for our sandwich snacks then trampled our bodies into the bog. Old postcards show it as an oval enclosure quite separate from the main lake.

      Once past the soggy hollow put to such grim use by the fictitious (but very vicious) Macaterick clan, the path bends southeast across a flank of Meaul to reach the corner of Loch Valley. It runs along the loch’s western end, then down beside its outflow, the Gairland Burn. The path here can become very soggy; an alternative path is to the left of the stream.

      After 1km down the high hidden valley, the path contours out to the right – a ‘seat stone’ is alongside the stream here. The path, of peat puddles and tall rounded boulders, is tiring in descent. After passing behind a knoll there’s a view of Loch Trool ahead, and the path slants down through bracken to the track running through the woods beside the loch.

      Follow the track ahead, past Buchan farm, with its conical turret almost buried among the oaks, and across Buchan Burn below a waterfall. Where the uphill track bends right, take a small path ahead. The peat has eroded away to bare rock on the short pull up to Bruce’s Stone.