Took one of my favorite humans to one of my favorite NH geologic wonders- Turtle Mountain- site of a large volcano- estimated by some to have been a 10,000 foot high peak before it erupted, but whatever the size- three eruptions left behind the volcanic ring dike, mostly recognizable from satellites far above.
We checked out the columnar basalt on the slope up to Bald knob, and then walked on the top of Turtle Mtn., the mostly hexagonal columns on the summit, which look like scutes on a turtle’s shell.
Addendum- Jamie Hannon’s comment below reminds me that Connor and Dan Hole Pond on the eastern side of the 40 mile circumference, 9 mile diameter ring complex are thought to be the remnants of ancient gas vents of the volcano.
Dan Hole Pond’s maximum depth is 130 feet. Newfound Lake is the reported deepest in the state at 180 feet.