Genesee River

The Genesee River's name is derived from the Iroquois meaning good valley or pleasant valley. It flows northward through western New York from its source south of the town of Genesee in Pennsylvania and empties into Lake Ontario north of the City of Rochester, New York. The river drains about 2500 square miles (6,500 sq. km.). Falls along the river are within the gorge of Letchworth State Park (the Grand Canyon of the East) near Portageville, New York and within Rochester, where they provided power to 19th century industry. A dam at Mount Morris is the largest flood control dam east of the Mississippi. It has greatly reduced flood damage in the lower Genesee Valley; its capacity has only been exceeded once, during the great flood of 1972, caused by the remnants of Hurricane Agnes. Although the floodwaters went over the spillway, the flooding was partly ameliorated below the dam. The dam was completed in 1952.

Geology

Main article:

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The present river valley has been modified extensively from preglacial river valleys. The original river had two branches. The east branch has a larger preglacial valley. It runs south of Mount Morris. It was completely blocked by extensive terminal moraines just south of Dansville, so most of the upper section was diverted toward the Susquehanna River system. Now only a small creek flows in what is left of this large valley. The west branch, which was smaller, is now the Genesee River above Mount Morris.

Related Topics:
Preglacial - Moraine - Susquehanna River

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The present river is the western branch of the preglacial system. Along its entire course, the rock layers are tilted to the south an average of forty feet per mile, so the river flows across progressively older bedrock as it flows northward. It rises in the highlands of the Allegany Plateau in conglomerate, sandstone and shale rocks of Mississippian and Pennsylvanian age, passing through and often exposing older rocks as it drops. At Letchworth it exposes shales, siltstones and some limestones of Devonian age. At Rochester it again cuts a canyon with three more waterfalls in limestones and shales of Silurian age. The river is a highly favored area for fossil collectors, as one can find a great variety from a very long time span, within the short course of the river.

Related Topics:
Conglomerate - Sandstone - Shale - Rock - Mississippian - Pennsylvanian - Siltstone - Limestone - Devonian - Silurian - Fossil

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