Upton State Forest consists primarily of low hills and valleys, with elevations ranging between 250 and about 600 feet.

The area is underlain granites and gneiss dating to about 610 million years before present. A recent bedrock geology map prepared by the United States Geological Survey includes parts of Upton State Forest.

Upton State Forest’s surficial geology is strongly influenced by the most recent (Wisconsinan) glaciation which covered central Massachusetts with ice between about 23,000 and 14,000 years before present. The glaciers exposed underlying bed rock in some areas and deposited deep layers of sand, gravel and glacial till in others.  Blocks of ice left by retreating glaciers formed depressions which developed into lakes, ponds, and wetlands as the ice melted.  Boulders deposited by retreating glaciers dot the landscape in many locations.  Soils are generally quite stony and not well suited for agriculture.