Through the day, the weather had been fine but warm. At sunset a thunder-storm rose in the west; and the day was succeeded, almost without any interval of twilight, by the most impenetrable darkness. The wind soon rose to a tempest; and hailstones of uncommon magnitude began to fall, accompanied with thunder and lightning. Our first thought was to dismount from our horses, and shelter ourselves from the hail on the leeward side of their bodies. We were in the middle of an extensive prairie, where no other protection could be looked for. The hailstones, however, diminished in size, and soon ceased to fall; but such torrents of rain ensued, that the plain became inundated, and the frequent flashes of lightning were reflected to our eyes from the surface of a vast lake. The plains in many places having little inclination, the water of a sudden shower is drained off less rapidly than it falls. After raging with great violence for a short time, the storm ceased; but the darkness was so intense, that we did not arrive at the settlement, where we proposed to lodge, until a late hour in the night. Soon after crossing the Missouri, we had ascended so far as to reach the general level of the great woodless plain; and after travelling a few miles, we found the surface sloping to the north-east towards the Mississippi. In the afternoon, we crossed the Darden, which enters the Mississippi eight miles above the mouth of the Illinois; and on the following morning the Cuivre, tributary to the same river, ten miles above the other.[56] The point between the Missouri and Mississippi, near their confluence, is raised in the highest parts, probably less than one hundred and fifty feet above the water-table. It is of a deep and fine soil, which would appear rather to have subsided from the waters of a quiet ocean, than to have been brought down from above, and deposited {98} in its present situation by the rivers. Between the sources of the streams which descend from either side of this narrow cape, extends an irregular tongue of land, destitute of timber, and every where nearly of the same elevation; as if it had been a part of the great plain, left naked at the retiring of the ocean, and in which the vast vallies of the Missouri and Mississippi had since been excavated by the operations of those streams. The smaller rivers of this region appear, both in extent and direction, to have been wholly independent of any peculiar conformation of the original surface on which they commenced their course; and their present beds gradually deepening, and descending in the nearest direction towards the vallies of the great rivers, are in every respect such as we may suppose to have resulted from the wearing away of a great and uniform plain. At a house where we rested in the middle of the day, and which was in the highest part of the country between the Missouri and Mississippi, here sixty miles distant from each other, a well had been sunk sixty-five