The beach or sloping part of the immediate bank of the Ohio, throughout its whole extent, is of rather gradual ascent, and covered with timber a considerable distance below high-water mark. The average rapidity of the current of the Ohio is about two and a half miles per hour, and the descent of its surface nine inches per mile, as estimated by Dr. Drake of Cincinnati. The annual inundations happen in the spring. The range between extreme high and low water, in the upper part of the river, is more than 60 feet; but below, where it is not confined by high banks, it is much less.
About the falls of Ohio, the cane, (myegia macrosperma of Persoon,) begins to be seen, and increases in quantity thence westward to the Mississippi. The "Cave Inn Rock," or "House of Nature," which we have before mentioned, is an immense cavern penetrating horizontally into a stratum of compact limestone, which forms the river bank for some distance above Golconda in Illinois. Its entrance is a large and regular arch, placed immediately on the brink of the river, and a similar form is preserved in some degree through its whole extent. The Battery Rock is a high mural precipice of the same stratum, running in a straight line, and forming the northern bank of the river which washes its base. The face of this precipice is smooth and naked, and it is surmounted { 40} by a heavy growth of timber. This limestone is compact, entirely horizontal in its position, and filled with organic remains. It is traversed by veins containing sulphuret of lead; and at several places near Golconda, this is accompanied by fluat of lime, in beautiful yellow and violet-coloured crystals. Fluat of lime is also found disseminated in small and irregular masses throughout the rock. At Golconda, six miles below the cave, a coarse gray flinty sandstone is found, extending some distance to the west. This rock forms broad hills on the Kentucky side, between the Cumberland and Tennessee rivers; where it abounds in iron ore of several kinds. Perhaps these hills ought to be considered as a spur from the Cumberland hills. At the mouth of the Tennessee river, is a locality of the columnar argillaceous oxide of iron, which rises from the surface in pyramidal and columnar masses, somewhat resembling the cypress knees.