We will be following in the footsteps of history. The ground we will walk on was created over the last 450 million years, as the southern part of the North American Continent rose and fell below sea level, alternately laying down layers of sediment that were compressed into stone by the weight of succeeding layers at the bottom of the oceans and eroded away by the elements when the land lay exposed above the oceans. Much of our journey will cross the great drainages of the center of the continent starting about 285 million years ago when the orogeny of the Rocky Mountains blocked the flow of rivers draining the continent to the west from the slopes of the great eastern mountains of the then young Appalachian mountains (formed in a series of continental collisions between 500 and 300 million years ago.
Geological Map of Louisiana
When we started this latest version of the Great Virtual Journey we realized that this was a very special course. And we wanted the virtual journey to be as much like the real journey as possible. A real journey run is a total experience. There is so much to see and experience along the way. Something new around every bend and over every hill. To bring the true experience of the journey to you we have created 62 Waypoints along the course. When your daily run takes you past one of these waypoints you will receive an e-mail with that day’s discoveries. They may be history, prehistory, geology, or just the sights you will see today. We do not want you to only total the miles, we want you to feel yourself walking in the tracks of the buffalo, the Indians, the pioneers, the Kaintucks, and everyone else who has walked this great route over the past 400,000 years. We are starting your journey with two waypoints upon entry to the race. Over the next 632 miles you will discover the wonders of the great Natchez Trace! I promise the other waypoints will not all be this long. Some just pictures. But there is a lot to tell at the beginning of your great journey!
As we travel we seldom pay that much attention to road cuts. They are just conveniences to make it easier to travel without climbing every hill or descending every steep slope. But road cuts are much more than that. Every one of them lays bare the story of the land over which you are traveling. The soil and rock that are exposed are like great storybooks, telling the tale of life on earth at the time that soil and rock was laid down. When you see the layers each one tells a story of life, and every line between layers tells of a changing earth. All 5 of the great extinctions occurred while the land we will walk on was being formed. Anywhere from 60 to 90% of the living things on earth went extinct. And following each of these extinctions there was a period of great flourishing; when life blossomed and branched out to re-fill the earth. Starting on the banks of the mighty Miss’ippi we are on the newest of ground. We are out on the delta of the Old Man River, which has laid down this land over the past 11,700 years, since the last glacial period ended.
We tend to think of rivers as timeless. Truth is, rivers are generally among the youngest features on the face of the planet. Although there has been some big river draining the center of the continent since the mountain ranges blocked drainage except to the south, the Miss’ippi itself only traces its roots to the end of the last ice age. And even since then it has been in a state of continuous change. If you look at the borders of the states of the lower Miss’ippi, you will see how the river’s course has altered, leaving chunks of each state on the wrong side of the river.
As a matter of fact, you are only starting on the banks of the Miss’ippi as it is today because the army corp of engineers is forcing it to stay in it’s channel. For over 100 years it has been trying to change course into the Atchafalaya River, which is a shorter and steeper route to the Gulf. Maintaining the Miss’ippi flow to the ports of Baton Rouge and New Orleans has become an ever more difficult task, which many believe will eventually fail. Water tends to go where it wants to go!
At the edge of the new land of the Miss’ippi delta we come to Lake Ponchartrain. This lake was not formed by any hollowing out process, but rather the successive layers of silt dropped by the Miss’ippi over 12,000 years of spring floods actually cut off an inlet of the Gulf, and formed the south bank of the lake.
After the lake you will move onto older alluvial deposits with a glacial origin, formed between 11,700 and 2.5 million years ago during the Pleistocene Ice Ages. They are called the Terraces because there are 3 distinct layers, laid down at different times. These were produced by smaller rivers and were once the shore of the Gulf, before the Miss’ippi formed by the combination of several drainages to start entering the gulf and eventually lay down its own deposits to form the south bank of Ponchartrain!). The terraces are mostly clay and sand, with some gravel.
After you cross the Terraces you will enter the Citronella and Willis Deposits. These are pre-ice age, forming during the Pliocene between 2.5 and 5.5 million years ago. They are formed of red sand, clay, and gravel that was washed down by smaller, more localized rivers, rather than coming from the entire continent.
You will be on the Citronella and Willis Deposits all the rest of the way into Miss’ippi.
Wonderful description of where we are heading and how it got to be.
You are going to love it.