We were somewhat surprised to see here a flock of black-headed terns. It is remarkable that these birds, whose ordinary range is in the immediate vicinity of the sea-coast, should ascend this river to so great a distance. They are not seen on the Delaware as high as Philadelphia, unless driven up by storms. In ascending from the mouth of the Missouri to Bellefontain, a distance of four miles, our boat grounded twice on the point of the same sand-bar, and considerable time was consumed in efforts to get her afloat. A military post was established at Bellefontain, under the direction of the government of the United States, by General Wilkinson, in 1803; but the soil on which his works were erected has disappeared, the place being now occupied by the bed of the river. A few fruit trees only, which stood in the end of his garden, are yet standing, but are now on the brink of the river. The first bank is here ten or twelve feet high, rising perpendicularly from the water. Near its base are the trunks of several trees with one end imbedded, and the other projecting horizontally over the surface of the water, affording an evidence of the recent deposition of the soil of the low plains, and an admonition of the uncertainty of tenure, on the first bank of the river. One of these projecting trunks is still in good preservation. It is {62} about three feet in diameter, and from its direction, must pass immediately under the roots of two large trees, now occupying the surface of the soil.[088] Similar appearances are frequent along the Mississippi and Missouri, and furnish abundant evidence that these rivers are constantly changing their bed, and, from the great rapidity of the stream, as well as from the appearances presented, we must suppose these changes are not very slowly produced; but their range is confined to the valley within the second banks, which are here raised about seventy feet. On this second bank, in the rear of the site of the former works, the buildings belonging to the present military establishment have been erected. They were commenced in 1810. The houses are of one story, constructed of logs, based upon masonry, and united in the form of a hollow square. At the foot of the second bank rises a fine spring of water, which has given name to the place. Cold Water creek, a very small stream not navigable, discharges itself a few hundred yards above; in times of high water its mouth might afford harbour to small boats. Before the recent change in the bed of the Missouri, this creek entered higher up than at present, and then afforded a good harbour for boats of all sizes. The sixth regiment were encamped here at the time of our arrival, waiting for the contractor's steam-boats, three of which we had passed at the mouth of the river.[089]