Page:Popular Science Monthly Volume 38.djvu/760

740 particularly at its head-waters, where it tumbles over and around rocks in the wild and reckless exuberance of youth. It abounds with trout, and furnishes scenery well worthy the attention of artist or student of nature.

The Monongahela itself has become somewhat celebrated of late years, because of certain terraces found along its banks, the history of which has been the source of considerable speculation. They are found in the vicinity of Morgantown, W. Va., and are composed of silt, clay, and loam, with a few animal and many plant remains scattered throughout their extent. They vary from 70 to 275 feet above low water in the river, but have an approximate elevation of from 1,045 to 1,065 feet above tide. Evidently produced by the action of water, they are yet too far removed from the present stream to have been formed by its agency, at least in its present condition. An explanation of their origin will be suggested later on in the course of this article.

The other branch, which unites with the Monongahela, is the Alleghany. This takes its rise in the northwestern part of Pennsylvania, enters New York State for a short distance, turns south again, and joins its sister stream at Pittsburg. It does not rise in a mountainous country, but in a region comparatively level; and there is every reason to believe at one time in its existence it was tributary to Lake Erie instead of to the Ohio. It is some four hundred miles long, and is navigable for small boats for two hundred and fifty miles from its mouth. It flows through the great oil and gas region of Pennsylvania, a region which gave to the world over 150,000,000 barrels of petroleum. It is from here, too, that has come the gaseous fuel which has changed Pittsburg from the smokiest city of the Nation into one of the cleanest. Pittsburg, besides being a great manufacturing center, is the starting-point for the great coal fleets that supply the cities of Cincinnati, Louisville, and hundreds of others with the fuel taken from the mines of Pennsylvania. Prom this point begins the Ohio River proper. We may glance now at its history, and trace briefly the vicissitudes through which it has passed from its birth to the present time.

The actual birth of the Ohio River dates from the close of the Carboniferous or Coal era, and the final elevation of the Appalachian chain of mountains. Previous to that time the country through which the river now flows lay upon the borders of the ocean, and in places was lost in the ocean itself. After the land was elevated above the sea-level, the drainage system of the valley was established, and the great river was born.

All streams in the course of their existence go through several phases, which correspond to the features presented by the different parts of their course. The head-waters are swift and roaring