Mount Tom is western Massachusetts's highest traprock peak and the southernmost summit of the Mount Tom Range, rising sharply above the Connecticut River Valley. Formed from volcanic basalt as ancient faulting tilted hardened lava layers, it supports varied microclimates and rare plant communities. The mountain became a major recreation destination in the trolley era, with a railroad, Mountain Park, and summit houses, though the summit buildings repeatedly burned. It also figured in regional logging drives, later gained roads and structures built by the Civilian Conservation Corps, and hosted a ski area from 1962 to 1998. A 1946 B-17G crash site and memorial mark one of its most tragic landmarks.