Franklin County, Massachusetts: the world’s best place to study geology! Be prepared to be amazed! Most people think of geology as “just a bunch of rocks”, but exciting Earth events are recorded in rocks and landscapes, too. Franklin County has magnificent landscape scenery: mountains, waterfalls, rushing rivers and meandering ones, such as New England’s longest river, the Connecticut. We also have quite a bunch of rocks, too, including famous ones with dinosaur footprints plus we also have something truly unique: the world’s only petrified armored mud balls. Intrigued?
More on those later.
Here is the geology story of Franklin County and surroundings, greatly summarized. In the Paleozoic Era western Franklin County was the underwater edge of the North American continent. Tectonic plates came from afar and collided to make the super continent of Pangea. Those collisions created metamorphic rock out of the old ocean sediment. Franklin County was now “landlocked” in the middle of mountains, the young Appalachians now mostly eroded. The photo is the prominent roadcut along Rte. 2 in Erving. It shows metamorphic rock (schist) with quartz “pods” called boudins (French for “sausage”). These are rocks from the deep middle of mountains exposed by three hundred million years of erosion.