“When fast moving river meets a slow-moving or still body of water, it almost comes to a halt and deposits its load of sediment, sand and silt, in the still body of water.” This is how the Mississippi built the Louisiana Coastal marshes over the last 7,000 years. And this is out the Mississippi, aided by the Red River, deposited huge oil reservoirs under the layers and layers of mud, and the layers and layers of rock, and under the cap of salt that seals it all under the bottom of the sea.
And, it turns out, with the silt and sand came dead organisms that did not decay in the naturally low-oxygen environment, the Dead Zone, that is the Gulf of Mexico. Without oxygen the micro-organisms that came with all that silt and sand were cooked into oil.
Joel Achenbach explained much better than I in an article a week ago in the Washington Post. Read it and you will understand three things: First, continued deepwater drilling is going to happen because the oil is there. Second, even without global climate change, we have to wean ourselves from carbon based fuels, oil and coal, and from nuclear, because they are not going to be there forever. And third, we have to learn now how to use wind and solar, the sun and all the plants it nourishes in Midwest fields year after year after year.