10,000 years ago the most recent Ice Age still held huge amounts of
water in the ice caps so sea levels were much lower and the mouth of
the river was far to the south, out in what is now the Gulf.
As the ice melted the sea level rose and finally stabilized about 5,000 years ago.
The mouth of the Mississippi retreated northward and established a
delta south of Baton Rouge, far to the west of its current location.
Since then the river's course has changed about every 500-1,000 years
establishing seven distinct lobes of high land and creating lakes
Maurepas and Pontchartrain.
New Orleans is built on three of these lobes. The Metairie and Gentilly
ridges across the center of the city are what remains of the natural
levee created 2,000 years ago when the river bed was two miles north
of its current position.
Click on the image to see an expanded view.
The Times Picayune animation called The Rise and Disapperance of Southeast Louisiana captures the story in words and images. Turn your volume up.