Baudolino crosses the Sambatyon

It was indeed the river of stone, as they realized when they arrived at its banks, dazed by the great din that almost prevented them from hearing one another's words. It was a majestic course of rocks and clods, flowing ceaselessly, and in that current of great shapeless masses could be discerned irregular slabs, sharp as blades, broad as tombstones, and between them, gravel, fossils, peaks, and crags.

       Moving at the same speed, as if driven by an impetuous wind, fragments of travertine rolled over and over, great faults sliding above, then, their impetus lessening, they bounced off streams of spall, while little chips now round smoothed as if my water in their sliding between boulder and boulder, leaped up, falling back with sharp sounds, to be caught in those same eddies they themselves had created, crashing and grinding. Amid and above this overlapping of mineral, puffs of sand were formed, busts of chalk, clouds of lapilli, foam of pumice, rills of mire.

       Here and there sprays of shards, volleys of coals, fell on the back, and the travelers had to cover their faces so as not be be scarred. . . . By then, for two days, they had seen above the horizon an impervious chain of high mountains, which loomed, almost blocking their view of the sky, crammed as they were in an ever narrower passage, with no exit, from which , way, way above, could now be seen only a great cloud barely luminescent, that gnawed the top of those peaks.

       Here, from a fissure, like a wound between two mountains, they saw the Sambatyon springing up: a roiling of sandstone, a gurgling of tuff, a dripping of muck, a ticking of shards, a grumbling of clotted earth, an overflowing of clods, a rain of clay, a gradually transformed into a steady flow, which began its journey towards some boundless ocean of sand. . . . Then, more and more impetuous, the Sambatyon subdivided into myriad streamlets, which penetrated among mountainous slopes like the fingers of a hand in a clump of mud; at times a wave was swallowed by a grotto, then from a sort of rocky passage that seemed impassable, it emerged with a roar and flung itself angrily toward the valley . . .

       There were cataracts that plunged down from dozens of rocky eaves arranged like an amphitheater, into a boundless final vortex, an incessant retching of granite, an eddy of bitumen, a sole undertow of alum, a churning of schist, a clash of orpiment against the banks. And on the matter that the vortex erupted towards the sky, but low with respect to the eyes of those who looked down as if from the top of a tower, the sun's rays formed on those silicious droplets an immense rainbow that as every body reflected the rays with varying splendor according to its own nature, had many more colors than those usually formed in the sky after a storm, and, unlike them, seemed destined to shine eternally, never dissolving.

       It was a reddening of haematrites and cinnabars, a glow of blackness as if it were steel, a flight of crumbs of aureopigment from yellow to bright orange, a bluness of armenium, a whiteness of calcinated shells, a greening of malachite, a fading of liothargirium into saffrons ever paler, a blare of risigallam, a belching of greenish earth that faded into dust of crusocolla and then transmigrated into nuances of indigo and violet, a triumph of aurum musivum, a purpling of burnt while lead, a flaring of sandracca, a couch of silvered clay, a single transparence of alabaster.

Umberto Eco, Baudolino: A Novel.  Translated by William Weaver. (from pp. 357-360)