The Allegheny Plateau

(c) Copyright 2002 Andrew Alden, licensed to About.com, Inc.

All day when I showed you the view north into the Mohawk Valley, I didn't show where the view was from. The great classic Devonian section of central New York makes up the northern edge of the Allegheny Plateau. This afternoon spectacle looks at the plateau from a point west of West Slaterville, on state route 79. The rocks of the plateau are younger—Late Devonian shales and sandstones of the Sonyea and West Falls Groups, around 360 million years old. Farther east, rocks of this age piled up to a much greater thickness because their source region was closer. That pile makes up the Catskill Mountains.

Here, though, there are no high peaks, only a level summit surface that has been dissected by rivers and—in this region—by glaciers. The ice rounded these ancient hills by scraping off their deep mantle of soils, leaving the core of harder bedrock behind. Much of the scraped-up material, or till, was dropped when the ice melted, choking the streambeds with sediment. Because of the overabundance of sediment and the tilting of the crust in response to the ice's comings and goings, drainage has been slow to re-establish itself since the ice ages. Streams tend to be slow-moving and meandering, prone to floods.

These hills mark the southern edge of the Finger Lakes drainage area. The glacier-carved valley leading away, to the south, is drained by the sluggish Wilseyville Creek, which eventually leads to the Susquehanna River. The area in front drains northward to the Great Lakes.

Scenery like this extends down the inland side of the Appalachian Mountains from here all the way to Alabama. But this day I had to turn from that temptation and drive back to Albany, awaiting the day I can come here again.

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