During the Ice Age, the ice shelves contained significant amounts of water resulting in the sea levels approximately 150 feet below where they are today. This extended the shore line in many places, tens or hundreds of miles from where they exist today.
Places like New Orleans would be far inland and more akin to Vicksburg or Natchez, Mississippi. So, more fertile plains, not wetlands. During this time frame, the Mississippi was also much larger than it is today. Then, the river would have normally been around seven to eight miles wide. To see the far coast would have been impossible, standing on the shore, due to the curvature of the earth.
Deltas would have extended out into this land being the most fertile while the upper lands of this old shore line would not have been as fertile. This Ice Age coastline would also be very flat, possibly ideal for farming. Allowing small towns and villages to farm, hunt, fish and trade.
If a civilization was settling the world back then, they would most likely settle along the coasts. Coasts and rivers would allow trade back to their home city and provide a means to feed a larger population. Settlements near water for a global civilization would allow the population one last defense, fleeing via the sea.
A global civilization would be great seafarers and explore the world. Throughout history, nations of seafarers have explored far and wide. This would probably be true of any nation before known history,too. Most of these seafaring societies stayed near water, which would probably be true of a prehistoric civilization as well.
In Wall of Destruction, this is how my Atlantean civilization works. They are a global civilization of seafarers with colonies near the coasts and along major rivers. They trade with other peoples near their colonies.
A passage from the book with a little information on this civilization (vailixi is the Atlantean flying craft powered by aether):
“Tilor, let them know we are returning and our status.” Risor smirked, if Jamal survived then this would be his mess to explain. How convenient he would blunder into a trap, lose half of his command and then die to ensure he doesn’t get blamed. This on top of the last raid, command will probably try to place the blame on me, he thought.
After a few minutes, in an uncharacteristically bewildered response. “Sir, there is no response.”
“No sir, nothing, no chatter. Nothing. Nothing from Vortia either.” Vortia being the capital of the Sundaland colony and his base the only defense of the capital beyond it’s own aether spears and shielders.
“Check all communications channels and distress channels.” turning to Dimera. “What do you feel Dimera.” Did the Ramans use their brahmastras on Sundaland? They were still an hour away from Sundaland so it would be a while before they can visually inspect what happened.
“Any other vailixi in the air?” To anybody.
After a few minutes, “Sir, I have a fleet vessel on the merchant channel. The Poseidon’s Servant, sir.”
Before Risor could ask. “Audio only sir, weak signal.”
Risor sighs, now would be a good time to have a visual and higher level communications link but of course many of the merchant fleet do not even have aether enabled systems. The merchant fleet being used for commerce and regional passenger runs. The vailixi are almost all for the military or government use with just a few for global passenger runs back and forth to Atlantis. The majority of the merchant fleet are as they have been for thousands of years, wind driven surface only vessels. A few have been upgraded to use aether enabled systems that allow them to go against the wind or some even to dive but they are rare and reluctantly not what the Poseidon’s Servant is equipped with.
“Poseidon’s Servant this is Commander Tarnor of Falcon Claw squadron. Where are you and what is your situation? We have been trying to raise Vortia without any luck.”
“Commander, this be Captain Volck, we are outside of what is left of Vortia’s harbor. The city is gone, sir. We were running fruits from the Xuli tribes up north for ..” static overcomes his talking.