Abstract

The preglacial rivers of southwestern Ohio, northern Kentucky, and southeastern Indiana flowed toward the north and joined with the west-flowing trunk river, the Teays, in central Ohio. The main tributary valleys to the Teays River in this region—containing the Old Kentucky, Manchester, and Old Licking Rivers—were meandering and incised to a depth of 30 to 60 m (100 to 200 ft) below the upland level. The bedload carried by these rivers had a distinctly southern source.

During the first glacial advance into central Ohio and Indiana in pre-Illinoian time, the Teays drainage was dammed, and impounded waters filled the valleys. East of Cincinnati in the Manchester and Old Licking River valleys, thick lacustrine clays were deposited. West of Cincinnati, however, in the Old Kentucky River basin, there is very little lacustrine sediment, suggesting that either (1) the Old Kentucky River was not ponded because its flow had already been reversed as a result of preglacial piracy by the west-flowing Old Ohio River, or (2) glacial ponding occurred but was short-lived because overflow from the Old Kentucky River basin west into the Old Ohio River basin caused rapid downcutting of the divide between these basins.

Thick lacustrine sediment in the Manchester and Old Licking River valleys indicates a long period of water impoundment. Hence, deepening of the spillways between this lake and the Kentucky River basin to the west must have taken place very slowly. The lake probably existed for many years before the addition of water overflowing from the Teays tributaries in southeastern Ohio, West Virginia, and western Pennsylvania began to contribute to spillway erosion.

Eventually, probably as a result of this initial glaciation, a new west-flowing Ohio River was established, approximately along its present course from Pittsburgh to southern Illinois. The new river closely followed the trend of the Teays-age valleys but seldom coincided with those old meandering valleys in the Cincinnati area. Entrenchment of the new Ohio River took place soon after the old valleys were abandoned, leaving many high-elevation preglacial valley remnants south of the pre-Illinoian glacial boundary.

The initial post-Teays drainage pattern was modified in several places when Illinoian glaciation, and, possibly, a second pre-Illinoian advance (stade?) invaded the Ohio River valley north of Cincinnati and at several points to the east and west of the city.

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