Trip to Crag Mountain

This trip was to Crag Mountain, which is a "roche moutanee" (a glacially carved ridge) that is visible across the river from the NMH campus.  Our goal was to gather rock samples from two outcrops - one an igneous pegmatite containing extra large crystals of potassium feldspar and muscovite to observe, and the other a metamorphic schist that has beautifully layered biotite crystals.  Our initial visit was just to collect the samples which we are identifying in the lab, along with our study of perhaps 20 other common rock-forming minerals.  Later, we will fit these outcrops into a bigger picture of the Acadian orogeny, a major mountain-building period in the Paleozoic era that created a mountain range as high as the Himalyan mountains stretching along much of New England, Nova Scotia, Greenland, Great Britain, and Scandanavia (back when Europe and North America were part of a single great continent named Pangea.

At the top of the roche moutanee, we looked at the view back to campus across

the river, observed the dates carved into the bedrock by Amherst College fraternities one hundred years ago, and then looked more closely to see grooves carved in long parallel bands across the rock.  These grooves were scoured out by the glaciers which covered New England during the last Ice Age, until about 18,000 years ago.  The glaciers also carved out the landscape we see today.  All that remains of the ancient Paleozoic mountain ranges are the basement rocks that now form our present landscape - rocks that were once buried under thousands of feet of rock and sediment, and now are finally being exposed at the surface through slow uplift and erosion.

Our geology class is made up of juniors, seniors, and postgraduates who want to take a science course that is taught at the college level but does not have the AP workload.  The topics we study include the formation of the earth and solar system, plate tectonic theory, minerals and rock formation and identification, and geologic time.  A significant part of the class involves field trips to local outcrops, since we live a valley that happens to have a great variety of rock types and historical geologic environments. We supplement textbook learning with direct observations and rock and mineral identifications to develop a scientific story about the history of our region.  Students in the class include:  Charley Dickey, Ryan Fluence, Chris Green, Hector Harold, Jonathan Hernould, Alex Jundanian, Chris Mangan, Danny Shin, Sloane Thomson, and Max Wright.

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