In 1685, part of a rock, forming one of the impending cliffs, became so undermined by wind and rain, that loosing its hold, it fell in several immense masses, and in its passage down a steep and craggy cliff, dislodged some thousands of other stones. The largest piece of the falling rock continued its motion through a small meadow, and rested on the further side of the river Ogwen. In the winter of 1831, another part of the rock gave way, when upwards of one thousand tons fell from near the summit of Benglog, a little below the Ogwen cataracts; part rolling straight across the road, fell into the valley and river at the bottom; while another part having acquired a less momentum, rested on the road; the intercourse of travellers was for some time impeded, although one hundred miners were engaged in clearing the surface of the road. A gentleman from the vale of Llanrwst had just passed along in his carriage, on his way to Bangor, when the terrific sound of the dissolving mountain fell upon his astonished ear.
The mountains at the upper end of this vale form a scene singularly grand; on each side the hollow appears guarded by a huge conical rock, Trivaen on the right, and Braich-dû on the left. These, with the Glyder-vach and the Glyder-vawr, and some other mountains, fill up the distance, and apparently close the vale.
Near this place, beside a little gothic cottage, is a small hone quarry, Y Trivaen, which received its name from three tall stones standing in an upright position on its summit, and from below had the exact resemblance of three men. Of these only two remain.
One mile from Ogwen lake, in a deep valley, lies a dark pool, called
Llyn Idwal.
The gloomy horrors of the surrounding scenery exceed even those of Ogwen; the encircling cliffs are overhanging, broken, and dark; in one part the whole mountain is rent asunder, and the chasm of Twll dû (or the Black Cleft) gapes between the terrific masses. The solitude of Cwm Idwal proved favourable to the perpetration of a deed of blood, and it was here that young Idwal, the infant heir of Prince Owen Gwynedd, was treacherously assassinated, by order of his foster-father Nefydd, to whose care his father had consigned him.
Miss Costello gives the following description of this romantic region:—
“We were not induced to linger very long in the slate quarries, being more desirous to make ourselves acquainted with the undisturbed nature which invited us on the way to Capel Curig.
“The Vale of Nant Ffrancon is wild and stupendous in the extreme; it is an extensive marshy valley, filled with peat, whose black masses are piled in all directions in stacks; numerous alleys filled with the water which drains from it, are cut through the turf on whose surface the graceful cotton plant waves its feathery and snowy tresses, covering the swampy ground, and lending it beauty; numerous water flowers of bright colour give some life to the scene, which would otherwise be inexpressibly dreary. Huge masses of crumbling rocks bind in the narrow valley, and assume the strangest and most grotesque shapes, as though the visions of the Welsh bard, Davydd ap Gwilym, were realized, and
“‘There were in every hollow
A hundred wry-mouthed elves.’