Wetlands have a life cycle that begins with their formation and may involve many changes over time.

Formation

Many wetlands were formed when glaciers retreated after the last Ice Age, about 10,000 years ago. Some of the glaciers left depressions in the ground, called kettles, which were perfect places for water to gather. In some places, buried ice melted to form kettle lakes that eventually turned into wetlands.

Wetlands are formed by the overflowing of river banks and changes in sea level, which can leave waterlogged areas behind. (the average height of the sea) Some wetlands are formed with help from beavers making dams that cause rivers or streams to back up and flood the surrounding area. Landslides or centuries of heavy winds may also change the terrain or carve out depressions in the ground where water then collects.

Climate, too, plays a key role...