Poplar Mountain in Erving MA is (as they say) the "type locale" for Poplar Mountain Gneiss. Erving Conservation Commission (with help from Mount Grace Land Trust) has developed a series of trails that presently run up to the bottom of the Mountain's summit where one can view plenty of the gneiss in the exposed ledges. My hike was with mostly local people, some from the conservation commission, and one representative from Mt Grace Land Trust.
For the following hike, I jumped south across the Millers River and on into the Wendell State Forest. A beautiful walk along a secluded brook, a view of Lynn Falls, and a climb up through the Hidden Valley Memorial Forest (once again - Mt Grace Land Trust property) brought me to some VERY impressive rock ledges. Farther along the Metacomet - Monadnock Trail, one crosses a main forest road with significant overhanging ledges and some 'quasi' cave formations. With the main gate at the State Forest entrance locked, it only remained to walk the road back on out.