{"id":11641,"date":"2023-10-03T00:50:07","date_gmt":"2023-10-02T23:50:07","guid":{"rendered":"https:\/\/www.aboutriver.com\/?p=11641"},"modified":"2023-10-03T00:50:07","modified_gmt":"2023-10-02T23:50:07","slug":"whats-at-the-bottom-of-the-mississippi-river","status":"publish","type":"post","link":"https:\/\/www.aboutriver.com\/whats-at-the-bottom-of-the-mississippi-river\/","title":{"rendered":"What’s At The Bottom Of The Mississippi River"},"content":{"rendered":"
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Geology of the Mississippi Riverbed<\/h2>\n

The Mississippi River, flowing from the Midwestern states of Minnesota, Iowa, Wisconsin and Illinois to the Gulf of Mexico, is one of the longest rivers in the United States, measuring more than 2,300 miles long. Its bed, an intersection of sandy and rocky materials, reveals along its entire length a varied profile of geological formations that have been shaped over millions of years by the might of its steady flow.<\/p>\n

From its source at Lake Itasca to the Mississippi Delta, where the iconic deltaic network extends into the coastal waters of Louisiana, geologists have divided the rivers bed into six major divisions. In the Upper Mississippi Valley, the river winds through a series of bluffs that sedimentary rocks and limestone outcrops form. Following the valley of the Iowa and Wisconsin, the riverbed transitions in the Middle Mississippi Valley to an Illinois upland composed by quartzite, limestone and dolostone. Here, lower river speed allows the accumulation of fine grains, creating a sedimentary wedge.<\/p>\n

Continuing southwards, the Lower Mississippi Valley is the site of a distinct eolian feature, the Grand Prairie of Arkansas, composed of the post-glacial loess deposits. Further downstream, in the area between the confluence of the Mississippi and the Ohio rives, the alluvial floodplain is composed of sediment loads from both tributaries. This deposits form a fine-grained sedimentary wedge that narrows as it continues to the rivermouth.<\/p>\n

The formation of this varied geological landscape has been determined by two main factors. The geological formations along the banks of the Mississippi were created over millions of years as its waters eroded and deposited sediment in distinctive layers. Additionally, the diverse landscape of the riverbed is greatly affected by the Mississippi’s system of distributaries and floodplain features, which modulate its speed of flow.<\/p>\n

Geomorphic Characteristics<\/h2>\n