The wild recesses of these hills, like those of the Rocky Mountains, are retreats and lurking-places for broken and predatory tribes, and it was among them that the remnants of the Cheyenne tribe took refuge, as has been stated, from their conquering enemies, the Sioux.

The Black Hills are chiefly composed of sandstone, and in many places are broken into savage cliffs and precipices, and present the most singular and fantastic forms; sometimes resembling towns and castellated fortresses.  The ignorant inhabitants of plains are prone to clothe the mountains that bound their horizon with fanciful and superstitious attributes.  Thus the wandering tribes of the prairies, who often behold clouds gathering round the summits of these hills, and lightning flashing, and thunder pealing from them, when all the neighboring plains are serene and sunny, consider them the abode of the genii or thunder-spirits who fabricate storms and tempests.  On entering their defiles, therefore, they often hang offerings on the trees, or place them on the rocks, to propitiate the invisible “lords of the mountains,” and procure good weather and successful hunting; and they attach unusual significance to the echoes which haunt the precipices.  This superstition may also have arisen, in part, from a natural phenomenon of a singular nature.  In the most calm and serene weather, and at all times of the day or night, successive reports are now and then heard among these mountains, resembling the discharge of several pieces of artillery.  Similar reports were heard by Messrs. Lewis and Clarke in the Rocky Mountains, which they say were attributed by the Indians to the bursting of the rich mines of silver contained in the bosom of the mountains.

In fact, these singular explosions have received fanciful explanations from learned men, and have not been satisfactorily accounted for even by philosophers.  They are said to occur frequently in Brazil.  Vasconcelles, Jesuit father, describes one which he heard in the Sierra, or mountain region of Piratininga, and which he compares to the discharges of a park of artillery.  The Indians told him that it was an explosion of stones.  The worthy father had soon a satisfactory proof of the truth of their information, for the very place was found where a rock had burst and exploded from its entrails a stony mass, like a bomb-shell, and of the size of a bull’s heart.  This mass was broken either in its ejection or its fall, and wonderful was the internal organization revealed.  It had a shell harder even than iron; within which were arranged, like the seeds of a pomegranate, jewels of various colors; some transparent as crystals; others of a fine red, and others of mixed hues.  The same phenomenon is said to occur occasionally in the adjacent province of Guayra, where stones of the bigness of a man’s hand are exploded, with a loud noise, from the bosom of the earth, and scatter about glittering and beautiful fragments that look like precious gems, but are of no value.