Capulin Volcano National Monument
East of raton preserves a relatively recent volcanic field centered on the capulin cinder cone, believed to have erupted about 6000 years ago. the visitor center open days except some holidays; $5/car fee, park pass applies is on the volcano's crater rim, and trails from here reach the rim and the floor of the crater. there are other volcanic features in the immediate area of the monument.
Fort Union National Monument
Just north of i-25 east of las vegas, preserves ruins of an important 19th-century fort along the santa fe trail. a short interpretive trail winds through the ruins. open days except holidays, fee park pass.
Clayton Lake State Park
If you're interested in paleontology, Clayton Lake State Park, about 15 miles northwest of Clayton, is well worth a visit owing to an unusually rich bed of fossil dinosaur tracks that was unearthed during excavation to build the spillway for the man-made lake. A short hike around the lake reaches the tracks and interpretive displays. You can try water sports while you're there, but don't expect Lake Mead. Day-use access to the park costs $5 per car and is not covered by an NPS Park Pass, as this is a state, not national, park.