'It emerges frothing from that unseen darkness to fall like a tumbling cascade of brilliants into a deep rounded cauldron enclosed by rock walls on three sides, black water in whorled black rock, with the fleecy white spume ringing the blackness of the pool. Up above the black sides of the pot there are dark-green watery mosses growing deep and cushioned wherever there is a finger-hold for soil; the domed nest that the dippers build here every year is distinguishable from the other moss cushions by nothing but its symmetry. The sun reaches the waterfall for only a short time in the afternoon; it forms a rainbow over the leaping spray, and at the top of the fall between the boulders it gives to the smooth-flowing, unbroken water the look of spun green glass.'
from Ring of Bright Water
by Gavin Maxwell