the rivers in question are bounded on both sides, as they often are, by perpendicular cliffs of sandstone or limestone {323} in horizontal strata, the seams and markings on one side correspond with those on the other, indicating the stratifications to have been originally continuous. A ride of a few miles in a direction passing obliquely from the river, brought us to a point which overlooked a large extent of the surrounding country. From this we could distinguish the winding course of a small stream, uniting numerous tributaries from the ridge we occupied, and pursuing its course towards the south-east, along a narrow and well-wooded valley. The dense and verdant foliage of the poplars and elms contrasted strongly with the bright red of the sandstone cliffs, which rose on both sides, far surpassing the elevation of the tallest trees, and disclosing here and there masses of sulphate of lime of a snowy whiteness.[68] Looking back upon the broad valley of the river we had left, the eye rested upon insulated portions of the sandy bed disclosed by the inflections of its course or the opening of ravines, and resembling pools of blood, rather than wastes of sand. We had been so long accustomed to the red sands, that the intensity of the colouring ceased to excite any attention until a distant view afforded us the opportunity of contrasting it with the general aspect of the country. The elevated plains we found covered with a plenteous but close-fed crop of grasses, and occupied by extensive marmot villages. The red soil is usually fine and little intermixed with gravel and pebbles, but too sandy to retain moisture enough for the purposes of agriculture. The luxuriance and fineness of the grasses, as well as the astonishing number and good condition of the herbivorous animals of this region, clearly indicate its value for the purposes of pasturage. There can be little doubt that more valuable and productive grasses than the native species can with little trouble be introduced. This may easily be effected by burning the prairies at a proper season of the year, and sowing the seeds {324} of any of the more hardy cultivated gramina. Some of the perennial plants common in the prairies will undoubtedly be found difficult to exterminate, their strong roots penetrating to a great depth and enveloping the rudiments of new shoots placed beyond the reach of a fire on the surface. The soil of the more fertile plains is penetrated with such numbers of these as to present more resistance to the plough than the oldest cultivated pastures.