Answer:
The Mississippi River and its alluvial plain houses a rich fauna and flora that make up the largest marsh system in the North American continent, therefore, the settler must cross this system in order to settle.
Step-by-step explanation:
The marshes are wet-type ecosystems with the presence of water, as well as a low and superficial vegetation that covers all the water but does not dry it. This system is usually found in regions near the sea.
The marshes, depending on the depth of the terrain, can become navigable. They are able to trap and bind sediments, so they act as a filter for pollution. They constitute a habitat for animals, especially migratory birds that use the marshes as a place to rest and feed during their long trips.