Cape Cod is the largest glacially formed peninsula in the world, and the Great Beach, on the Atlantic side of the Cape, is the longest expanse of uninterrupted sandy shoreline on the East Coast. Here you can see sand spits and barrier island that separate salt marshes and tidal flats from the open ocean, and precipitous marine scaprs (or "cliffs") carved by the incredible energy of ocean waves and tides. These dynamic systems provide the raw material for the extensive dunes at the tip of Cape Cod. This area, known as the Province Lands, was built long after glacial retreat by wind and waves transporting unconsolidated sands - a process that continues today. South of the Province Lands and between the beaches, the retreating glaciers left behind a topographically complex landscape formed by the interplay between melting ice and deposition of glacial outwash. The legacy of the Cape's glacial origins and the influence of wind and waves set the stage for a number of diverse habitats and natural features. We often group these into four basic ecosystem types:
Beaches, barrier islands, spits, and dunes: The Seashore encompasses miles of ocean beaches and the expansive dunes of the Province Lands. The plants and animals that live in these areas are specifically adapted to cope with their highly dynamic environment. Species that depend on these habitats include the Federally-listed threatened piping plover ( Charadrius melodus ) and State-listed endangered oysterleaf ( Mertensia maritima ).
Estuaries and salt marshes: These wetland systems typically have relatively flat topography, are regularly flooded and drained by the tide, receive freshwater input from groundwater, and are protected from ocean waves by barrier beaches or other landforms. In some of the Cape's estuaries, past construction has restricted tidal flow degrading water quality and impacting native plants and animals. The Seashore is working to remedy past damage by restoring tidal influence where possible.
Ponds and fresh water wetlands: The interaction of the Cape's hydrological processes with its complex and varied topography sets the stage for many diverse fresh water systems. Kettle ponds, vernal pools, bogs, swamps, and dune slack wetlands dot the Seashore from the southern end of Nauset Beach to the Province Lands. Each of these fresh water systems supports a distinct assemblage of plants and animals.
Coastal uplands: Between the beaches, the outer Cape is dominated by pitch pine and oak forests. These forests provide habitat for a large number of species from fungi and lichens to coyotes and deer. The Cape's upland also includes patches of coastal heathland and grasslands. These habitats are globally uncommon and the species that occupy them are correspondingly rare.