The short answer
- There is very strong evidence against the notion of a recent worldwide flood.
- There is no known mechanism by which a flood could create the patterns in the fossil record.
The longer answer
Robert J. Schadewald offers six arguments that cast great doubt upon the idea of a historical worldwide Noachian Flood that created a fictitious fossil record:
 The Karoo Formation contains the remains of some 800 billion vertebrate animals. If one conservatively estimates that the Karoo Formation contains a mere 1% of the vertebrate fossils on earth, this means that before the flood the earth would have held 2100 vertebrates of varying sizes per acre.
 If marine fossils comprise 0.1% of the volume of sedimentary rock, this means that before the Flood these organisms would have covered the earth to a depth of at least 1.5 feet.
 The varves of the Green River formation would, by the standard interpretation, take 20 million years to form. For the varves to have been formed during the Flood by shallow flows of mud-laden water (as the creationists conjecture), would have necessitated a sequence of 40 million flows covering tens of thousands of square miles every two-thirds of a second.
 Noah, his wife, his three sons, and their wives—being the only human occupants on the Ark (Genesis 6:18, 7:13)—must have carried all of the diseases specific to man in their bodies, were the disease organisms to survive the Flood. Given that only two of most of the animals of each kind were on board, some of the specific disease organisms known today would have been wiped out by the eventual immunity of the two.
 Hydraulic sorting during the Flood [the mechanism creationists invoke to try to explain why the fossil record is not just a huge jumble] would have caused large trilobites to have always been found in lower strata than small trilobites, because of hydrodynamic drag properties. This is not what is actually found. Victim habitat and mobility arguments are similarly shown to be wrong be the fact that fossils of flowering plants—despite their relative immobility and their existence at all elevations—never appear before the Cretaceous era.
 There are overturned strata, explainable by conventional geology, but impossible to explain by the working of the Flood. How could the Flood cause upside down raindrop craters and brachiopod burrows? (Schadewald 1983:448-453).
Although more than enough for their purpose, Schadewald’s six objections only scratch the surface of problems with the creationist’s flood. For a more comprehensive treatment, the reader can do no better than Mark Isaak’s talk.origins article on the subject.
Schadewald RJ. 1983. Six ‘Flood’ arguments creationists can’t answer. In Zetterberg 1983:448-453.
Zetterberg JP (ed.). 1983. Evolution versus Creationism: The Public Education Controversy. Phoenix: Oryx Press.