Titus Livius (Livy), The History of Rome, Book 21
Benjamin Oliver Foster, Ph.D., Ed.

36. They then came to a much narrower cliff, and with rocks so perpendicular that it was difficult for an unencumbered soldier to manage the descent, though he felt his way and clung with his hands to the bushes and roots that projected here and there. [2] The place had been precipitous before, and a recent landslip had carried it away to the depth of a good thousand feet.¹ [3] There the cavalry [p. 107]came to a halt, as though they had reached the end² of the road, and as Hannibal was wondering what it could be that held the column back, word was brought to him that the cliff was impassable. [4] Going then to inspect the place himself, he thought that there was nothing for it but to lead the army round, over trackless and untrodden steeps, however circuitous the detour might be. [5] But that way proved to be insuperable; for above the old, untouched snow lay a fresh deposit of moderate depth, through which, as it was soft and not very deep, the men in front found it easy to advance; [6] but when it had been trampled down by the feet of so many men and beasts, the rest had to make their way over the bare ice beneath and the slush of the melting snow. [7] Then came a terrible struggle on the slippery surface, for it afforded them no foothold, while the downward slope made their feet the more quickly slide from under them; so that whether they tried to pull themselves up with their hands, or used their knees, these supports themselves would slip, and down they would come again! Neither were there any stems or roots about, by which a man could pull himself up with foot or hand —only smooth ice and thawing snow, on which they were continually rolling. [8] But the baggage animals, as they went over the snow, would sometimes even cut into the lowest crust, and pitching forward and striking out with their hoofs, as they struggled to rise, would break clean through it, so that numbers of them were caught fast, as if entrapped, in the hard, deep-frozen snow.