Trimountain is a traprock peak on Connecticut’s Metacomet Ridge, southeast of Meriden, notable for its triangular shape, three southern pinnacles, and steep cliffs rising to about 760 feet. Formed from basalt during the rifting of North America from Africa and Eurasia near the end of the Triassic Period, it developed rugged faces, dry upper slopes, cool ravines, and mineral-rich talus that support uncommon plant communities and migrating raptors. Though quarrying has heavily cut its western side, its southern pinnacles and wooded eastern slopes remain open for recreation. Protected land, local conservation work, and its place on the Mattabesett Trail have made it part of broader efforts to preserve the Metacomet Ridge.