Claim CD211: Mississippi delta could have formed in 5,000 years
Brief response in the Index to Creationist Claims in the TalkOrigins Archive.
Young-earth "proof" #19: The size of the Mississippi River delta divided by the sediment accumulation rate gives an age of less than 30,000 years.
Article by Dave E. Matson on the Secular Web site. Also available in the TalkOrigins Archive.