All the other left-hand tributaries of the Dnieper flow in broad valleys, with high right slopes and low left slopes, covered with stagnant waters, marshy meadows and areas of sand. But, altho they all look very imposing at the time of the spring floods, yet, neither the Sula with its high wooded banks, nor the Psiol with its 670 km. of length, neither the Vorscla flowing along between sandbanks and dunes, nor the Orel sliding slowly along with its twisted course—none of these have any significance for [82]navigation. Only the steppe-river Samara, flowing between granite banks, is capable of floating rafts along a short stretch. There was a time, however, in which all these rivers were navigable, even for ships of considerable size. Great old anchors and wreckage of ships, which are found in the beds and banks of these rivers, are sufficient proof of this fact. The cause of the present condition may be sought in the destruction of forest in the drainage country. The spring floods, increased from this cause, develop considerable destructive activity, filling up the river bed with masses of sand and mud, floating brushes and stumps of trees. The decreased volume of water in the dry season, due to the drying up of the swamps and springs, can not transport these deposits further, and the river becomes unfit for any sort of navigation. The Don (Din) is the fourth in the series of rivers of Europe. It is over 1800 kilometers long, but the country it drains is smaller in area by 100,000 square kilometers than that of the Dnieper. Hardly one-fourth of the Don country belongs to the Ukraine, and even less of its course. For this reason it was long considered as a border stream of the Ukraine on the east, until the past century extended the boundaries of Ukrainian territory into the Kuban region and to the Caspian Sea.