I appreciate Professor Richard Little’s fascination with the bedrock at Shelburne Falls. Yes, those banded rocks — metamorphic gneisses — gained their present form hundreds of millions of years ago while buried many miles below Earth’s surface, subject to enormous pressures and temperatures that would make them glow a dull red.
But let’s face it: tourists come to Shelburne Falls to see the potholes. And those potholes are indeed far, far younger than the rock into which they’re carved — 14,000 years ago sounds about right. They are products of erosion by torrents of gravel-laden meltwater from our last retreating ice-age glacier.
One should not confuse these two bits of history, any more than one should confuse the sculpting of a bust of George Washington with the origin of the marble it’s carved from!
I realize that Professor Little knows all this, but readers could get a very wrong impression from your headline. Those potholes are indeed glacial.
Bryce M. Hand
Emeritus Professor of Geology
Syracuse University