Im not even gonna paste your drivvle about the Miss delta since , unless your head was in a melon for the last 3 years, you could have seen that deltas are very dynamic situations, subject to onshore forces, river deposition, weather, etc. Katrina wiped out an area a bigger than Delaware in 3 nights and yet you wish to use this as a calculation for a young earth.
The Miss Delta is about 60 mY old, lies atop a prograde predelta sequence of continental slope sediments very similar to the Baltimore canyon -continental shelf along the mid Atlantic states.
The delta is NOT 40 ft thick, as a complex , its way ove 350 meters thick and then it intersects with earlier paleozoic prodelta features.
The delta is made up of 4 distinct regional overlapping sequences(the Plaquimines modern,the LaFourche,St Bernard,Teche,and Maringouin) each with a distinct "lobe" all the way N of Baton Rouge to hundreds of miles S of New Orleans. The Plaquimine, that which surounds and protects New Orleans with its "cheniers of sand" , was literally wiped away by Katrina leaving New Orleans a target unless the Army Corps decides in its wisdom to stop restricting sediment flow which builds the deltas.