Beavers at Troy

For years geologists have wondered what physiographic (earth-changing) agency caused wide alluvial plains--like the nine-mile valley floor east of Troy, N. Y.--which are out of all proportion to the deposits attributable to their present small streams. Last week Geologists Rudolf Ruedemann and Walter J. Schoonmaker of the New York State Museum solved the riddle, and at the same time implied that either geologists should get outdoors more or, when they did get out, should be looking at other things besides rocks. The physiographic force which had caused the Troy plain, and others like it, was the beaver.

Hordes of beavers have lived in the northern half of North America during the 25,000 years since the glaciers receded. As beavers still do, they built dams. When one pond filled up they went a little farther upstream and built another. When the whole valley was a series of muddy terraces the beavers went off to another stream. Then the stream broke through the dams one by one and carried a huge load of silt down to the bottom of the valley, forming an alluvial plain.

For generations New York State farmers have called these plains beaver meadows but geologists failed to take the hint.

"Geologists," mildly observed Geologists Ruedemann and Schoonmaker, when announcing their rediscovery of the beaver, "apparently have overlooked this important geologic agent."

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