Geologist John Slack points out the contact zone between the 400-million-year-old Phillips granite (white rocks in background) and the 415-million-year-old metamorphic rocks (dark, foreground) in the Sandy River near Phillips to field trip participants on Aug. 14. Pictured are Ron Haines, left, Sharyan Auger, Slack, Sonja Schaetzle, Jennefer Baxter, Henry Braun, Joan Meerman, Klara Haines and an unidentified man. Not pictured are Wilfred Cushing, Paul Ellis, Tony Marcellino, Jacob Meerman, Paul Auger and Lucy Darlington.