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Where do freshwater marshes commonly form in the landscape?
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Wetland
Stately bald cypresses (Taxodium distichum) thriving in a Louisiana swamp.
Freshwater marshes are wetland ecosystems that form globally in low-lying areas where water collects or where relatively impermeable soil or geologic layers cause water to pond.1
These marshes commonly develop in several specific landscape settings:
- River Systems: They are frequently found at the mouths of rivers, particularly where extensive deltas have formed. They also occur along the vegetated fringes of small lakes and in segments of river systems that experience tidal action without salinity.213
- Depressions and Basins: Marshes often form in basinlike depressions where water is trapped. This includes prairie potholes, vernal pools, and playas. In some regions, such as the northern Great Plains, they occupy irregular depressions left by retreating glacial ice.21
- Coastal Areas: They can be found in coastal lagoons located behind the beaches of barrier islands.1
- Unique Topography: In areas near sea level, such as the Florida Everglades, marshes form where abundant rainfall cannot drain and remains on the surface.21