{147} CHAPTER VIII {VI}
The Platte—Desert Plains—Mirage—Arrival at the Rocky Mountains.
The Platte, called by the Otoes Ne-braska, (Flat river, or water,) is, as its name imports, almost uniformly broad and shoal. It is fordable at almost any place, except when swollen by freshets, which occur in the spring season, from the melting of snow, and occasionally during the other portions of the year, from excessive rain. Its bed is composed almost exclusively of sand, forming innumerable bars, which are continually changing their position, and moving downward, till at length they are discharged into the Missouri, and swept away to the ocean by that rapid and turbulent river.
The range of the Platte, from extreme low to extreme high water is very inconsiderable, manifestly not exceeding six or eight feet. This is about the usual height of its banks above the surface of the sand which forms its bed. The banks are sometimes overflowed, but evidently to no great extent. The rapidity of the current, and the great width of the bed of the river, preclude the possibility of any extensive inundation of the surrounding country. The bottom lands of the river rise by an imperceptible ascent on each side, extending laterally to a distance of from two to ten miles, where they are terminated by low ranges of gravelly hills, running parallel to the general direction of the river. Beyond these the surface is an undulating plain, having an elevation of from fifty to one hundred feet, and presenting the aspect of hopeless and irreclaimable sterility.
The Missouri, in compliance with the usage of boatmen, hunters, &c., has been usually considered under two divisions; the lower extending from the {148} Mississippi to the confluence of the Platte, and the upper, comprehending all above that point. As might be expected, the influx of so large and so peculiar a river as the Platte, gives a new character to the Missouri below. It is more rapid, more difficult of navigation, and the water more turbid than above.
Among other plants observed about our encampment, was the wild liquorice, (glycyrhiza lepidota, N.) which is believed to be the plant mentioned by Sir A. Mackenzie,[97] which is used as food by the savages of the north-west. The root is large and long, spreading horizontally to a great distance. In taste it bears a very slight resemblance to the liquorice of the shops, but is bitter and nauseous. The leaves are frequently covered with a viscid exudation.
We were prevented from continuing our astronomical observations, in the afternoon, the weather becoming cloudy, and at evening a thunder-storm commenced, which continued with short intermissions during the night. The lightning exhibited an incessant glare, and peals of thunder which seemed to shake the earth to its centre, followed each other in rapid succession.
On Monday the 19th, we moved on, and ascending the Platte about thirty miles, arrived in the evening at a place where the hills on the north side close in, quite to the bed of the river. On both sides they became more broken and elevated, and on the north, they approached so near to the bed of the Platte, that we were under the necessity of travelling across them. We were glad, however, of any change of scene. The monotony of a vast unbroken plain, like that in which we had now travelled nearly one hundred and fifty miles, is little less tiresome to the eye, and fatiguing to the spirit, than the dreary solitude of the ocean.[98]
With this change of the surface, some change is observed in the vegetable products of the soil. Here {149} we first saw a new species of prickly poppy,[99] with a spreading white flower, as large as that of the common poppy of the gardens. The aspect of this plant is very similar to that of the common poppy, except that the leaves are covered with innumerable large and strong prickles. When wounded it exudes a thick yellowish sap, intensely bitter to the taste. On the summits of some of the dry sandy ridges, we saw a few of the plants called Adam's needles, (yucca angustifolia) thriving with an appearance of luxuriance and verdure, in a soil which bids defiance to almost every other species of vegetation. Nature has, however, fitted the yucca for the ungenial soil it is destined to occupy. The plant consists of a large tuft of rigid spear-pointed leaves, placed immediately upon the root, and sending up in the flowering season, a stalk bearing a cluster of lilliaceous flowers as large as those of the common tulip of the gardens. The root bears more resemblance to the trunk of a tree, than to the roots of ordinary plants. It is two or three inches in diameter, descending undivided to a great depth below the surface, where it is impossible the moisture of the earth should ever be exhausted, and there terminates in numerous spreading branches. In some instances, the sand is blown from about the root, leaving several feet of it exposed, and supporting the dense leafy head, at some distance from the surface.[100]