We came up to the broad, marshy floor of Cwm Eigiau the other day, just as the clouds were breaking to let sunbeams dance across the heathery shoulders of what is, in my opinion, a sombre hollow.

Part of the trouble is that for a large part of the day the light is contre jour as you go up towards the crags - you are looking at the shaded sides of Pen Llithrig y Wrach and Pen yr Helgi Du and so they appear as great, dark wedges threatening this constricted, rushy head of hollow. When rain is falling or about to fall, Cwm Eigiau isn't a favourite spot, but on this morning we were soon up above the abandoned slate workings and sloshing up the virtually pathless eastern flank of Carnedd Llewelyn, and the fitful sun was shining.

A path marked on the map hardly exists on the ground, so you must make your own way up to the broad, grassy top of the ridge. There's a fine view down into crag-girt Cwm Dulyn if you're lucky. Here is a hollow which contains a lake so forbidding that it was traditionally avoided by all wild swans and ducks and contained nothing but deformed fish. A causeway was said to run down into its bottomless waters and its farthest stone was called the Red Altar. It was believed that someone brave enough to stand on the causeway and throw water on the Red Altar could ensure rain before nightfall, even in the hottest weather.

We continued up to the lonely crest of the ridge as wet mist blew in from the west. It could well have been midwinter as we turned towards the south, towards the stony top of Foel Grach, and took temporary shelter in the refuge hut just below the 3,195 feet summit. Later in the day we traversed the broad top of Foel Fras (the rough hill) and turned down under brighter skies where Carneddau's wild ponies were grazing the steep ground above the Garreg-wen, turning their bright eyes on us in causal gaze as we passed on down towards the marshy valley floor.

There were more sunbeams now and soon we watched the heather slopes of Clogwynyreryr come alight as the clouds dissipated. The pale, clipped ewes and their maturing lambs shone, too, in their royal purple setting as we turned down the track beside the ancient sheep pens that made such a wonderful pattern of light and shadow as the sun fell towards the high ridge behind us.