Fowler Mountain, like much of the Metacomet Ridge, is composed of basalt, also called traprock, a volcanic rock.

The mountain formed near the end of the Triassic Period with the rifting apart of the North American continent from Africa and Eurasia.

Subsequent faulting and earthquake activity tilted the strata, creating the cliffs and ridgeline of Fowler Mountain.

Hot, dry upper slopes, cool, moist ravines, and mineral-rich ledges of basalt talus produce a combination of microclimate ecosystems on the mountain that support plant and animal species uncommon in greater Connecticut.

Much of the summit and the west side of Fowler Mountain has been conserved as part of the undeveloped Trimountain State Park and as municipal watershed land.