74o THE POPULAR SCIENCE MONTHLY. 



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 approxi- 

 mate 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 Penn- 

 sylvania, 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 hun- 

 dred 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 start- 

 ing-point for the great coal fleets that supply the cities of Cincin- 

 nati, 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 Appa- 

 lachian 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 val- 

 ley 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 tor- 



