MORPHOLOGY OF PARABOLIC DUNES FIELDS IN NORTHEASTERN NORTH AMERICA IN RELATION TO SEDIMENT SUPPLY AND WIND REGIME COMPLEXITY

Sand dunes are found on all continents on Earth. In arid and semi-arid regions, sand dune occurrence and morphology are well-document from ground-level field studies and aerial/satellite image interpretation. In humid and cold-climate environments, forest and wetland vegetation cover typically obscures stabilized dune fields. In formerly glaciated regions of northeastern North America, newly released open-sourced LiDAR (light detection and ranging) reveals hundreds of previously unreported dune fields and related morphology.

A wide variety of parabolic dune forms occur in northeastern North America under differing conditions of sediment supply and past sediment-transporting wind regimes. Stabilized dune morphologies formed under unidirectional winds range from individual dunes to merged parabolic dunes, parabolic ridges, and transverse parabolic dunes with increasing sediment supply. In addition, bidirectional winds, acting in succession, played a significant role in creating modified and compound parabolic dunes throughout the region. Specific examples of dunes developed under unidirectional winds and bidirectional acute, perpendicular, obtuse, and opposing successive sediment-transporting winds are shown. The range in parabolic dune forms is classified in relation to sediment supply and past sediment transporting winds. Past sediment-transport directions are mapped in relation to the timing of deglaciation and lake or sea level changes revealing a complex spatial-temporal pattern.