Was the Mississippi River Moved by Earthquake?
The Mississippi River is the second longest river and the most powerful in the United States, but it is still subject to the power and unpredictability of nature. Despite the river being a seemingly solid, permanent fixture of the United States, many have questioned if the river may have been diverted after a major earthquake event.
Some have posited that seismic activity over the last several thousand years may have shifted the course of the Mississippi river. According to experts, this is a possibility, however, additional evidence is needed to confirm a definite link between earthquakes and the movement of the river.
Since the 1970’s, geologists have eyed various crevices and rift valleys in the river valley with interest. These natural features offer evidence that an earthquake may have once shifted the river and its sedimentary layers.
A seminal study published by a team at the University of Alaska, Fairbanks, in 1991, noted signs of several thousand year old, earthquake-induced landslides that diverted the river. These landslides and shifting of the riverbed have been dated to around 3,000 to 4,000 years ago. Meanwhile, some have suggested that earthquake vibrations in prehistoric times likely caused the river to change course as well.
The 1991 study also suggests that the riverbed shifts which occurred in prehistoric times created what is known as the Chute-Au-Missi Cutoff. This ancient meander is geographically located at the northern tip of Lake Pontchartrain, Louisiana. It is thought by geologists that this meander marks the spot where, over 3,000 years ago, the Mississippi shifted course due to seismic activity.
Although the Mississippi has been slowly inclined against gravity for centuries, and has slowly changed course as a result, it is difficult to really know if earthquakes have played a major role in its movement. The evidence is still inconclusive as to the extent of this influence.
Comparison to Other Geological Events
In terms of other large-scale events, such as tsunamis and floods, scientific evidence points to earthquakes having the ability to cause substantial damage and alter the course of rivers. Studies of ancient earthquakes have suggested that these seismic protests have moved large masses of sediment, potentially leading to the formation of meanders, as well as river channel alterations and land uplift.
In order to further research the correlation between earthquakes and the moving of the Mississippi River, further archaeological evidence must be gathered and scientific analysis undertaken. Geologists report that data from seismometers today can shed light on the size and location of the magnitude-6+ earthquakes that would be required to cause a significant shift in the river’s course.
Ultimately, it is possible that earthquakes could have contributed to the changing of the Mississippi River’s course in the past, however, much more research is needed to determine the extent.
Impact of Earthquakes on Human History
Earthquakes have wrought substantial destruction since the dawn of time, and have shaped the course of human history. In areas that are particularly earthquake-prone, such as California and the Mediterranean region, seismic activity has not only changed the course of rivers, but also impacted entire settlements and agricultural systems.
For example, the disastrous Great Lisbon earthquake of 1755 destroyed the city, claiming up to 90,000 lives and creating a ripple-effect that ultimately contributed to the French Revolution in 1789. Meanwhile, smaller seismic events near the Nile in the 4th century BC flooded portions of the Nile Delta, creating a population dispersion that changed the course of ancient Egyptian history. Additionally, earthquakes are known to have caused the temporary flooding of the Tigris and Euphrates rivers, potentially having a role in the destruction of the ancient Sumerian empire.
Not only do earthquakes shape the land and human settlement, but also shape belief systems. In many cultures, early earthquake events were regarded as signs from the gods which needed to be understood and interpreted. It is no surprise, then, that earthquakes were regarded with considerable fear and awe, and this fear and awe persists today.
Tectonic Shifts and Effects on the River’s Course
Given the landscape of the Mississippi River, with the New Madrid fault zone located nearby, seismic activity could indeed have caused tectonic shifts that could have influenced the river’s course. Furthermore, large-scale floods over the years may have further shifted sediment layers and altered the river, requiring it to take a new course.
Geologists believe that a large-scale event is highly likely to have shifted the course of the Mississippi River, and seismic activity could have played a role. Given that there is an abundance of earthquake activity in the region, geologists point to this as evidence that the river’s course may have been changed due to seismic activity.
That said, this evidence needs to be further corroborated by additional research. Radiocarbon dating of sediment and archaeological levels can provide more definitive answers as to the timing of any prehistoric shifts in the Mississippi’s course. Along with seismometers, further research is needed to understand the true connection between earthquakes and the Mississippi River.
The Role of Humanity in River course Changes
Another consideration that is often overlooked when discussing the course of the Mississippi River and seismic activity is human influence. Through various engineering techniques, humans can influence the course of a river. That is, the river can be channelized, and its natural curve bent by creating dams and levees, as well as canals, to redirect a river.
This human intervention has certainly been done to the Mississippi River over the years, particularly in the 20th century. Dams such as the Gulfport Flood Control Dam, the Lower Pass Manchac Dam and the Atchafalaya Basin Levees and Floodways have all been constructed to help manage centuries of flooding and redirect the course and flow of the river.
Furthermore, during Reconstruction, New Orleans and its neighboring towns utilized levees and canals to help manage and redirect the course of the Mississippi as well. These human-constructed infrastructures have had an undeniable impact on the river’s course, and must be accounted for when considering seismic activity as a possible factor in the shifting of the Mississippi.
Mississippi River Delta Landscape Changes
Not only does seismic activity have the potential to change the actual course of a river, but it is also known to cause sea-level rises and other ecological changes. For the Mississippi River, this could mean that seismic activity leads to large-scale delta erosion, as well as vegetation changes, alterations in species living in the area, and new sedimentary deposits.
According to experts, in the event of an earthquake, large sedimentary deposits in the floodplain could be disturbed and a large-scale deltaic erosion could occur, leading to a massive siltation process. Furthermore, seismic activity could lead to a sudden increase in sea-level, introducing saltwater into areas where fresh water would have otherwise been.
It is also interesting to note that seismic activity could potentially lead to temperatures changes, as it is known to increase the rate of air circulation, subsequently raising the temperature in the area. This could be another factor influencing the course of the Mississippi, as well as the lives of the people and species living in the area.
The Mississippi River’s Resilience
Though the power of nature is still unknown and unpredictable, the Mississippi River has shown its immense strength and resilience over time. The river is a living testimony to the power of nature, and its enduring symbol of strength and endurance has inspired many throughout history.
The potential for seismic activity to change the course of the Mississippi is still very much up for debate, as inconclusive evidence remains on the issue. That said, if the river was indeed shifted by an earthquake, it speaks volumes to the resilience of the river, and of nature as a whole.
