The latter portion of the Pleistocene Epoch in New England saw the creation of Buzzards Bay through the interplay of glacial and oceanic processes. Beginning approximately 50,000-70,000 years ago, the edges of the continental ice sheet covering much of northern North America began to fluctuate, leaving linear masses of gravel, sand, and silt (known as moraines) to mark former extents of the ice. One such moraine forms most of the eastern shoreline of Buzzards Bay visible in this astronaut photograph.

In addition to the moraines, the melting ice sheet produced extensive plains of outwash composed of mixed sediments and ice that bordered the bay to the northwest and west. Melting ice blocks in the outwash deposits formed distinctive circular features called kettle lakes (or holes). Numerous examples of kettle lakes are visible to the northwest of the Cape Cod Canal. Finally, waters released from the melting ice sheet raised sea level by 60-120 meters (198-396 feet) and drowned preexisting outwash channels (visible as linear embayments along the western shoreline). Buzzards Bay attained its broad current configuration approximately 15,000 years ago; the current sea level was present approximately 3,500 years ago.