We thus find that the name, which has now become so celebrated, descends to us, through two translations, from those native races whose immemorial dwelling-place had been along the stream which it describes. What it was that led them to use the name is easily discoverable. The Yellowstone River is pre-eminently a river with banks of yellow rock. Along its lower course “the flood plain is bordered by high bluffs of yellow sandstone.” Near the mouth of the Bighorn River stands the noted landmark, Pompey’s Pillar, “a high isolated rock” of the same material. Still further up, beyond the mouth of Clark’s fork, is an extensive ridge of yellow rock, the “sheer, vertical sides” of which, according to one writer, “gleam in the sunlight like massive gold.” All along the lower river, in fact, from its mouth to the Great Bend at Livingston, this characteristic is more or less strikingly present.
Whether it forms a sufficiently prominent feature of the landscape to justify christening the river from it, may appear to be open to doubt. At any rate the various descriptions of this valley by early explorers rarely refer to the same locality as being conspicuous from the presence of yellow rock. Some mention it in one place, some in another. Nowhere does it seem to have been so striking as to attract the attention of all observers. For this reason we shall go further in search of the true origin of the name, to a locality about which there can be no doubt, no difference of opinion.
Seventy-five miles below the ultimate source of the river lies the Grand Cañon of the Yellowstone, distinguished among the notable cañons of the globe by the marvelous coloring of its walls. Conspicuous among its innumerable tints is yellow. Every shade, from the brilliant plumage of the yellow bird to the rich saffron of the orange, greets the eye in bewildering profusion. There is indeed other color, unparalleled in variety and abundance, but the ever-present background of all is the beautiful fifth color of the spectrum.
So prominent is this feature that it never fails to attract attention, and all descriptions of the Cañon abound in references to it. Lieutenant Doane (1870) notes the “brilliant yellow color” of the rocks. Captain Barlow and Doctor Hayden (1871) refer, in almost the same words, to the “yellow, nearly vertical walls.” Raymond (1871) speaks of the “bright yellow of the sulphury clay.” Captain Jones (1873) says that "about and in the Grand Cañon the rocks are nearly all tinged a brilliant yellow." These early impressions might be repeated from the writings of every subsequent visitor who has described the scenery of the Yellowstone.
That a characteristic which so deeply moves the modern beholder should have made a profound impression on the mind of the Indian, need hardly be premised. This region was by no means unknown to him; and from the remote, although uncertain, period of his first acquaintance with it, the name of the river has undoubtedly descended.
Going back, then, to this obscure fountain-head, the original designation is found to have been
Mi tsi a-da-zi, [E] Rock Yellow River.
And this, in the French tongue, became
Roche Jaune and Pierre Jaune;
and in English,