The Courts of the Morning by John Buchan

Black slept soundly all night, and next morning rose renewed in body and mind. The party set out down the glen of the stream, one of the Indians carrying food and blankets, while the other remained behind with the horses. Black had his pistol, but he had left his police carbine at the bivouac, while the newcomer had no weapon at all. "What do I want with a gun? " he had said lightly in reply to his companion's question. "We are going into the Poison Country -- El País de Venenos -- where lead and powder are trivial things. A gun is of as little use as a single lifebelt would be to a man proposing to cross the Atlantic in a skiff. We are now in the hands of the older gods."

It was a strange land which they entered, when the stream which they were descending plunged into the shadow of the high peaks. It was fed by many affluents, and presently became a considerable river, running in a broad grassy vale on which the dew lay like hoarfrost. Suddenly the hills closed in like a wall, and the stream leaped in a great spout into a profound ravine, where in potholes and cascades it poured its way from shelf to shelf of the mountain ribs. The sides of the glen were cloaked with bush, which in the lower levels became tall timber trees. In the woody recesses the freshness went out of the air, mosses and creepers muffled the tree-trunks, gaudy birds and butterflies flitted through the branches, and a hot, headachy languor seemed to well out of the sodden ground.