abyss seemed to be suddenly formed in the air.  The clouds followed each other into it with great velocity, till they attracted all objects around them, whilst such clouds as were too large and too far distant to feel its influence turned in an opposite direction.  The noise we heard in the air was like that of a tempest.  On beholding the conflict, we fancied that all the winds had been let loose from the four points of the compass.  It is very probable that if it had approached nearer, the whole caravan would have made an ascension into the clouds.  The spiral column moved majestically toward the north, and lighted on the surface of the Platte.  Then another scene was exhibited to view.  The waters, agitated by its powerful function, began to turn round with frightful noise, and were suddenly drawn up to the clouds in a spiral form.  The column appeared to measure a mile in height; and such was the violence of the winds, which came down in a perpendicular direction, that in the twinkling of an eye the trees were torn and uprooted, and their boughs scattered in every direction.  But what is violent does not last.  After a few minutes the frightful visitation ceased.  The column, not being able to sustain the weight at its base, was dissolved almost as quickly as it had been formed.

In proportion as we proceeded toward the source of this wonderful river, the shades of vegetation became more gloomy, and the brows of the mountain more craggy.  Everything seemed to wear the aspect not of decay, but of age, or rather of venerable antiquity.

The broad old Salt Lake Trail to the Rocky Mountains coincided with the Platte River about twenty miles below the head of Grand Island.  The island used to be densely wooded, and extended for sixty or seventy miles.  The valley at that point is about seven miles wide, and the stream itself, between one and two from bank to bank.

The South Platte was a muddy stream, and with its low banks, scattered flat sand-bars, and pigmy islands, a melancholy river, straggling through the centre of vast prairies, and only saved from being impossible to find with the naked eye by its sentinel trees standing at long distances from each other, on either side.

The Platte of the mountain region scarcely retains one characteristic of the stream far below.  Here, it is confined to a bed of rock and sand, not more than two hundred yards wide, and its water is of unwonted clearness and transparency.  Its banks are steep and the attrition caused at the time of spring freshets shows a deep vegetable mould reaching far back, making the soil highly fertile.  Here, too, the river forces its way through a barrier of tablelands, forming one of those striking peculiarities incident to mountain streams, called by the Spaniards a canyon; that is, a narrow passage between high and precipitous banks, formed by mountains; a common term in the language of the mountaineers describing one of these picturesque breaks through the range.