Figure 8. Some time after the rock solidified, it was affected by heating, probably during the interval from 400 to 385 million years ago. Some of the smaller minerals that are hard to see without magnification were produced at this time. These tiny minerals are called groundmass and occupy the spaces between the larger crystals.

---

Last updated on October 6, 2005

Maine.gov | Department of Conservation | MGS Home | Site Policies