I always found it strange that the Mississippi River extends several miles off the main coast of Louisiana. However I find it more strange that the River forks into three branches to flow out to sea.
Also the the western branch has land on both sides of it for several more miles before it's in open waters. I take all that is sediment that came from Canada and all the states north of Louisiana and from its tributaries like the Ohio and Missouri Rivers, called Delta. Still the long peninsula that La 23 follows can't be formed from just Delta alone considering only a few centuries ago the River had a completely different alignment. In fact it's the levee system that holds the current alignment in place.
What is the strange land masses that create a dual peninsula out into the Gulf?
A primer: https://en.wikipedia.org/wiki/Mississippi_River_Delta
He's got a real pretty mouth, ain't he?
All the rivers on the planet with that volume of water that are still narrow at their drainage point (Nile, Amazon, Mekong, etc) are like that.
Others with super high flow rates that widen early, where its hard to tell where the river ends and a bay/gulf starts (St. Lawrence for example), are the other way you'll see the largest of rivers end.
As the wikipedia page that Brandon noted shows, sediment has a lot to do with it as well.
Quote from: SectorZ on August 30, 2021, 12:58:50 PM
All the rivers on the planet with that volume of water that are still narrow at their drainage point (Nile, Amazon, Mekong, etc) are like that.
Others with super high flow rates that widen early, where its hard to tell where the river ends and a bay/gulf starts (St. Lawrence for example), are the other way you'll see the largest of rivers end.
As the wikipedia page that Brandon noted shows, sediment has a lot to do with it as well.
It's not just the largest of rivers. Plum Island in Massachusetts. New Castle Island and several others on the New Hampshire/Maine border. The Connecticut River also has a few.
If left to its own devices, the majority of the Mississippi's waters would have shunted over to the Atchafalaya basin to enter the Gulf around Morgan City by now. It's a shorter distance, therefore the gradient is higher. But we humans like having it flow past all these big cities and port infrastructure and industrial facilities we built, so we've maintained levees and stuff to keep the river flowing to the bird's foot.
As time goes on, the Mississippi delta will become an increasingly human-made feature. Depending how long we are willing or able to keep most of the water and therefore, most of the sediment, moving through New Orleans to the bird's foot, deposition at the existing delta could exceed land lost to subsidence, erosion and sea level rise and maintain a finger of land where the Mississippi ends. Compared to the continual subsidence and erosion of the rest of southern Louisiana, this could make for some interesting geography in the future. Unless we're smart about diverting enough water to bring in fresh sediment to replenish the wetlands that stand between New Orleans and The Gulf.
Way upstream where the border between Louisiana and Mississippi leaves the river and becomes east-west, there is something called "The Old River Structure". This is a dam built by the Army Corp of Engineers in the mid-20th century to keep the Mississippi River from shifting its flow into the Atchafalaya. It's used as an overflow outlet to help distribute some flood water from the Mississippi, but if were up to Old Man River, he'd rather send almost all the volume that way. It's a structure that, were it to fail, would leave humans with a tremendous task of trying to fix it to avoid leaving the existing channel high and mostly dry. Nothing's impossible, but there would be a need to take stock and decide if it's worth the expenditure of resources in the aftermath of an Old River Structure failure or shift our ports and, eventually, our cities over to the new channel.
The geography of the old Mississippi deltas is fascinating and once you notice the arcing lines of the abandoned deltas, you can't unsee them. The overlapping arcs define one's mental map of Louisiana. At least for me.