Shoreface retreat has removed more than half of the initial length of surviving Grandifolia dunes, a process that could only have occurred over thousands of years. Large parabolic dunes similar to these occur in contemporary periglacial regions. The Grandifolia Sandhills apparently began to form approximately 16,000 years before present when the last periglacial climate effected coastal New York. Many of these dunes ascended the east-west spine of the Harbor Hill Moraine and were stranded in their present position when winds powerful and persistent enough to move them dissipated as the climate ameliorated. Once established, this species helped modify dune sand into a soil that promoted its domination and taller forms.
Dwarfism occurs in places other than where the forest is undercut.
The pygmy form appears to grow in particularly stressed micro-environments such as dune crests. Dwarf trees are most abundant where the fabric of the forest runs down the steep Sound shore bluff to be continually cut back by slumping and other effects of storm waves. This biogeologic phenomenon appears to be globally singular. Preservation for scientific research, study, and education is recommended.