Its a bad idea, because you are taking the saltwater marsh away from the ecosystem... And turning it into a cement covered ground, for more houses... Then the animals (or other things) that live there, will die... and have to find another place to live...
~therefore... The bad thing is, that they shouldnt fill the marsh with dirt, and cement... Because bad things could happen to the creatures that already live there.
I believe the answer you are looking for is the "Neolithic Period".
The Mississippi river runs through 10 states in total before emptying out in the gulf of Mexico.
<span>Energy produced in the center of the sun
flows out through the sun's layers in different forms, including visible
light. The sun's interior generally becomes cooler and less dense as
you move away from the center. </span><span>Rising currents of hot gas in the convection zone carry energy toward the sun's surface.</span>
