Page:Popular Science Monthly Volume 75.djvu/483

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OHIO leads the states in its clay products, and its workable clays are practically inexhaustible. Ohio leads also in the number of presidents furnished the union, with unimpaired prospects for the future. Both ratings are consequences of geographic causes, as will appear in later discussion.

This state lies between 38° 27', and 41° 57' north latitude; it is bounded by the meridians reading 80° 34' and 84° 49'. For its width in latitude and its lack of great range in altitude, it has a marked range in mean annual temperature; in southern Ohio the mean annual range is 54°, while in northern Ohio it is 49°; its range in average temperature is about 40°. Lake Erie exerts an appreciable influence on climatic conditions for the northern part of the state.

The Ohio River bounds the state for 436 miles, and the lake shore I gives it 230 miles more of natural boundary. About one half of the! state line is artificial.

A rock section of the state gives in its lower half a predominance of limestone and shale formations; above this are wide-spread horizons of sandstone and conglomerate. These more resistant formations, belonging to the late Mississippian and early Pennsylvanian periods, are registered in the relief by a mild escarpment or cuesta sweeping to the south and west from the northeastern corner of the state. The northern and western parts consist of shale and limestone formations. There is slight relief particularly in the shale areas. The region of the limestone extends across the western portion of the state coinciding in longer axis with the orientation of the Cincinnati anticline. The drainage pattern resulting from this arching has given the west and southwest part of the state much more relief than would be the case with more horizontal strata.

The general dip of these formations is to the south and east. It is probable that the original consequent streams flowed in this direction. It would be futile, however, at the present time to attempt to sketch the drainage history of Ohio from the Pennsylvanian period, since which time the area has been continuously subject to stream work. Diastrophic movements have introduced some complexity. Several erosion cycles have been inaugurated, but there is evidence that few were