First-day Clay

First field day! After packing up on campus, we drove to Farmington and found this week’s base camp at the Troll Valley Campground. Intrepid scientists that we are, we were not intimidated by the prospect of the trolls being offended by our modern, albeit rustic, pursuits in their valley.

The major discovery of the day was on our first foray, northward from Farmington along the Sandy River. In a black fly-infested tributary valley, we found an outcrop with the most impressively plastic grey clay. Saint Joseph's student Jeff Boudreau holds up a sample of this Quaternary marine clay that a potter would covet. The presence of the clay overlain, first by silt then by sand and pebbles, indicates environmental conditions that changed from tranquil, relatively deep water (clay) to an increasingly energetic nearshore setting (sand and pebbles). This sequence is consistent with sediments accumulating as relative sea level was falling and the shoreline was moving southward through the area (termed a regressive sequence).