The temperate Laurentide Ice Sheet exhibited a grounded calving front as it retreated across coastal Maine about 14,000 to 12,500 B.P. The terminus resembled a modern tidewater glacier as the ice retreated through 0 to 80-m-deep water in the isostatically depressed region.

Many areas of coastal Maine exhibit structural features that affect Holocene coastal landforms. In southwestern Maine, these northeast-southwest–trending strike valleys and ridges formerly exerted strong control on glacial retreat rates and deposition along the ice margin. Deposition of small DeGeer-type moraines and larger, stratified, subaqueous moraines/fans occurred where structural ridges slowed ice retreat. As ice retreat continued landward into even shallower water, the retreat rate was slowed by structural ridges, and deposition prograded to sea level, producing ice-contact beheaded deltas. In some areas, bedrock ridges underlie Gilbert-type deltas, while in other situations, ridges protruded above sea level as hills or islands. Eskers connected to the proximal sides of the deltas indicate that ridges deflected subglacial water to the surface in these locations.