The greatest length of the _Valley of the Missouri_ is twelve hundred miles, its greatest breadth seven hundred. In the direction of the western rivers, the inclined plain of the Missouri extends eight hundred miles from the Chippewayan Mountains, and rather more than that distance from south to north, from the southern branches of the Kansas, to the extreme heads of the northern confluents of the valley. Ascending from the lower verge of this widely extended plain, wood becomes more and more scarce, until one naked surface spreads on all sides. Even the ridges and chains of mountains partake of these traits of desolation. The celebrated valley called the _American Bottom_ extends along the eastern bank of the Mississippi to the Piasa Hills, four miles above the mouth of the Missouri. It is several miles in width, and has a soil of astonishing fertility. It has all the disadvantages attending tracts of recent alluvion, the most valuable parts of it being liable to be swept away by the current of the Mississippi. ‘But the inexhaustible fertility of its soil,’ says Major Long, ‘makes amends for the insalubrity of the air, and the inconvenience of a flat and marshy situation, and this valley is undoubtedly destined to become one of the most populous parts of America. We were formerly shown here a field that had been cultivated, without manure, one hundred years in succession, and which when we saw it, (in August, 1816,) was covered with a very luxuriant growth of corn.’ The _Ohio Valley_ is divided by the river into two unequal sections, leaving on the north-west side eighty thousand, and on the south-east one hundred and sixteen thousand square miles. The river flows in a deep ravine five hundred and forty-eight miles long in a straight line, and nine hundred and ninety-eight by the windings of the stream. In its natural state the Ohio valley, with the exception of the central plain, was covered with a dense forest. Open savannahs commence as far east as the sources of the Muskingum. Like the plain itself, those savannahs expand to the westward, and on the Illinois open into immense prairies. This valley may be regarded as a great plain inclining from the Apalachian system of the north-west, obliquely and deeply cut by the Ohio and its numerous confluents, into chasms from an elevation of four hundred feet to nearly the level of the streams. On the higher parts of the valley, the banks of the river rise by bold acclivities which wear almost a mountainous aspect. This boldness of outline imperceptibly softens in descending the Ohio, and on approaching the Mississippi, an extent of level woodland bounds the horizon. Ascending the rivers of the south-east slope, the scenery becomes more and more rugged, until it terminates in the ridges of the Apalachian chains: if the rivers of the north-west slope are followed, on the contrary, we find the landscape broken and varied near the Ohio, but around their sources flat and monotonous.