ADSactly Education - Mississippi River Geology and Flow

in education •  last year 

The Mississippi River is by far, the mightiest river in America. The Mississippi River and it’s tributaries drain an area from the Rockies to the Allegheny Mountains, roughly 40% of the United States.

The river itself is entirely inside the US borders and runs 2320 mi (3730 km) from Lake Itasca in Minnesota to the Gulf of Mexico.

The Course of the Mississippi

The River is commonly divided into three parts. The upper, middle and lower. The upper River flows out of Lake Itasca in Minnesota at a very modest average flow of 6 Cubic Feet Per Second (CFS). It runs generally south and east through Minnesota to Minneapolis where a series of dams and locks make it a navigable waterway. The upper river continues on to St. Louis, Missouri where the Missouri joins it (and adds 45% of the combined flow). Total length of the upper river is 1157 miles, over half the total length.


The Middle River runs 190 miles from the confluence of the Missouri to the confluence with the Ohio in Cairo, Illinois. The Ohio River adds right at 50% of the flow of the combined river. The middle stretch of the river is relatively flat and free flowing with only two other rivers joining it.

The Lower Mississippi runs 1000 miles from Cairo, Illinois to the Gulf of Mexico, but not all in one channel. The main channel is split in Louisiana and roughly 30% of the River’s flow is diverted to the Atchafalaya River channel while the rest follows the current natural river channel past Baton Rouge and New Orleans, Louisiana and on to the Gulf. Average flow for the Mississippi River at the mouth (s) is 593,000 CFS.


There has been a river flowing north to south in the center of North America for a very long time. The biggest impact on the water course and the flow of the rivers in the last 15,000 years was the last ice age.


The river officially starts with Lake Itasca in north eastern Minnesota, an area that has an immense layer of glacially carried silt resulting in mostly flat plains. When the ice sheet receded the resulting water needed places to go. The flows were just tremendous which leaves the Mississippi and it’s tributaries with channels that are much larger than they need today. Another consequence of the ice retreating north is that many of the rivers that originally fed the Mississippi found their way north and empty into Hudson’s Bay.

The river has a total drop of 1475 feet (450m) from it’s headwaters to the Gulf of Mexico and more than half of that occurs in the upper river. Consequently the only real canyon of the Mississippi is on the upper river, but it’s pretty spectacular with near vertical walls. The reason for that is that the top stratum is silt laid down by the glaciers. Next is a relatively hard layer of rock with a layer of limestone and a layer of sandstone at the bottom. The sandstone is worn away by the flow of the water and it cracks and breaks straight up through the limestone and he hard cap.


For it’s first 300 miles (480 km) the Mississippi is a shallow, rocky river. After it passes through the Twin Cities, Minnesota it runs through a series of Limestone Bluffs which were formed by runoff water at the end of the last ice age. It also meanders through an area of steep valleys and hills with the canyon carved by the river itself.

The middle section of the river is characterized by high water flows and not much elevation drop where the river tends to be flat and wide. There is a tremendous amount of silt carried from the Missouri and some of the other tributaries on the middle river so the Mississippi in this stretch is brown. The Platte River, a tributary of the Missouri was described by settlers as “Too thick to drink and too thin to plow.” That silt contributes to the status of the lower river and the Delta.

The Mississippi wanders the last 1000 miles (1600 km) through swamps and forests that were all built up from the silt. Many of the swamps are former river channels that are filling up and drying out in the geologic scale of time. In a way, it’s all part of the river because it all has been part of the river in the last 15,000 years.


The lower river historically changes it’s course about every 500 years. Silt will pile up in one place and the river will simply find a way around the impoundment. The delta is a true ‘fan’ delta where the river often had no main channel, only a series of smaller outlets to the ocean. Today’s river is manipulated and maintained by man, so the channels are quite well designated. The delta continues to fan out and deposit huge quantities of silt at the merge with the ocean.

There is a confusing difference between the Mississippi Delta and the Delta of the Mississippi River. The Mississippi Delta is the area between the Mississippi River and the Yazoo River in the state of Mississippi. The Delta of the Mississippi River is the transition area between the freshwater flow of the Mississippi River and the saltwater of the Gulf of Mexico.

Almost the entire Delta of the Mississippi is in present day Louisiana, and the actual merge with the Ocean changes from year to year. Certainly the deepest part of the Mississippi is near New Orleans where the depth is right at 200 feet (67m). Most of the lower Mississippi is over 50 feet (17m) deep.


The Mississippi literally cuts right through the heart of America. Historically, it was the western boundary of the United States and was the dividing line between what was considered French territory and Spanish. Today it is considered to be the dividing line between the Eastern and Western United States.

We will explore the cultural history of the Mississippi in the next part of this series.

Unsourced Photos are used courtesy of the author.

While the words and ideas in this post are strictly those of the author these sources were referred to by me to insure numerical and historical accuracy.
Wikepedia: Mississippi River
Mississippi Valley Traveler: Mississippi River Geology

Authored by: @bigtom13

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The Mississippi River Basin is one of the world's largest development projects, with agricultural intensification and increasingly dense settlement of its banks, arms and deltas. The introduction of huge oil and natural gas deposits and the growth of New Orleans has only accelerated the modification or destruction of the rich and varied ecosystems of the delta (marshes and bayous) by urbanization, and the metropolis appears more and more vulnerable.

I agree that NOLA is very vulnerable. We will discuss that topic in a later part of this series.

I hope so thanks.

  ·  last year (edited)

The Mississippi River is by far, the mightiest river in America.

Wow 😮, 2320 mi, that’s much more than half the distance across entire United States. When I hear Mississippi River, first thing running through my mind is western movies. Of course most of them were watched in my childhood, but it stays in the back of my mind forever.

The lower river historically changes it’s course about every 500 years.

I guess that’s history, that’s past since it’s being manipulated by man. The deepest part of Mississippi at 200 feet is really surprising and it says about this river being the mighty of all. Great to find out another interesting information about US’s rivers and their history.

I have the same sorts of memories, and the truth is, the river had almost nothing to do with 'Western' culture except to hold some of the flood of humanity back. But it was such a big deal to cross it that it was included in a lot of Western scripts. It truly is an impressive river.

The mighty Mississippi is the quintessential symbol of America’s expansive geographic diversity.

As a side note, the Missouri River is actually longer than the Mississippi. (I know that you correctly mentioned that the Missouri is a tributary of the greater Mississippi waters, it’s amazing that it is actually longer on its own than the great Mississippi. The Missouri River is 2341 miles long. That’s amazing that it is almost exactly one marathon distance longer than the Mississippi.

Yep. I actually am aware. Had the country been settled West to East the Missouri would be the second longest in the world. (Presuming the Mississippi would end at the current confluence with the Missouri). Another 1000 miles would make it an impressive river.

River gorge history highlights

Spanning from downtown Minneapolis to roughly fort Snelling, our nearby river gorge is the only true gorge alongside the Mississippi'’s whole 2,350-mile period.
45,000 to twelve,000 years in the past, during the last ice age, glaciers superior and retreated generally over this vicinity to slough away all the younger or top layers of rock formations.
The glaciers melted 12,000 years in the past, forming a massive quantity of water to create our current rivers.
Saint Anthony Falls become shaped 12,000 years in the past close to what's now downtown Saint Paul. The falls receded upstream for 12,000 years to their modern-day region near downtown Minneapolis.

Yep, you have the only true gorge on the river, but it is a dandy. The walls are quite sheer because of the composition of the underlayment. I spent some time in the region just east of there this summer where there are rolling hills and fairly steep valleys. Impressive country.

Yep You @right dear @bigtom13:):):)

@bigtom13, First of all your work is really appreciable because this is deep and greatly subjected post regarding the Mississippi River. And whenever we talk about the water aspects and it's flow then that subject becomes really interesting because, there can be so many interesting inputs which we never know just exploring the pictures.

First of all i want to talk about the pictures, and through pictures i can say that, this is really breathtaking river, and picture with those flying birds just making an Picture Perfect effect. And for sure i can say that this river has to be one of the best explorative aspect.

And as you said, The lower river historically changes it’s course about every 500 years, showcase that nature is true artist because it's time to time self modify to change the course of it's cycle, and that's why i call Nature Is Everything.

I am not familiar with these aspects of The Mississippi Delta and Delta Of The Mississippi River, but good to know that difference because it's an informative subject for me and when we read without any background of it, then we can confuse between these two subjects and can consider both as one.

Keep up and wishing you an great day and stay blessed. 🙂

Thank you for the kind words. I promise to get to the Mississippi Delta (which is actually a flood plain) and the Delta (where the water flows to the ocean). The Mississippi Delta is the home of Blues and Jazz music. It does have a significant history.

Right now, man is having his say on the course of the river. I suspect you are right, and nature will have her way at some point in time.

Thanks for the kind words.

Welcome and good to hear these words, and good luck for your future study and exploration. Stay blessed. 🙂

  ·  last year (edited)

This River is a really big river and this river depth is around 200 ft so it flows so many waters in a year. Mississipi River basin is a big one in the world so that happy to see that they use that basin's water for agricultural intensification and we can probably say that this river is part of USA.

It is the absolute heart of our country. So much of our history and culture is wrapped around it and it is hard to explain outside the country. It embodies what we are. All of us.

This is a largest bridge ?

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It's not the largest bridge by any means. I think it's a beautiful bridge in a great setting. Without looking it up I think the largest bridge might be outside of Houston to the east. Or maybe Nashville.

So I had to go look it up. It's the Greenville bridge between the states of Mississippi and Arkansas. Now we both know.

v. Beautifull thanks for telling

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Hi @bigtom13! Thank you for this amazing post, I learned somthing new about the Missippi River!

Hey ya Tom. Thanks for stopping by. I'm a sort of a river rat, anyway so I've had big fun writing the whole series on the Western Rivers. Glad you liked it!

The truth is that every day I learned a lot here in Steemit about so many things and so many countries I have also known places through photographs

The Mississippi River I've heard a lot over the years I see it in movies, books or programs the truth is that it is very famous outside of there I did not know very well where it was and now I know a little more about it

It is a very famous river, and not all that well known. I'm glad you learned something about it today.

This is the largest river in America...

It is not the longest. The Missouri (a tributary) is longer. But by volume and drainage basin very much so.

OK... Thanks for the info

the river is the important things to our life, so we have to keep it clean, right?

This one could be kept cleaner in a lot of places. The flow is so large that a lot of the casual pollution seems relatively harmless, but it is cumulative. It will cause permanent harm.

I am a new follower brought me here the river Mississippi I think it is a good summary and concur when they say it is the heart or crosses the heart of America and the truth is that many have heard about this river I think it is one of the best known and I would like to go there some day and walk through its waters

It is quite literally, the heart of our country. I crossed it once this summer in a spot where it is only about 20 meters wide, and in another spot where it is over a mile wide :)

Welcome, I'm glad you found your way here.

A friend of mine is a cartographer and recently released this map called "The Watersheds of North America"

You can find him on Facebook

  ·  last year (edited)

I think the confluence of the Ohio and surrounding area is particularly fascinating. Actually the Cumberland, Tennessee, Green, Wabash, and others all converge in the earthquake-prone "American Bottoms" or "Little Egypt."