The Green River Formation is a geological formation containing in one place over 200 million alternaing thin light and dark semi-annual layers of sediment. If as creationists contend, geology was formed in a world wide flood of Noah lasting about a year, each one of these layers would have been deposited at a rate of about 1 layer per second! Furthermore, if a massive flood was the cause we would expect one big mis-mash of sediment, not an orderly sequence of layers of sediment.
Creationists often state that there are fossilized fish that penetrate some of these layers so these are not semi-annual layers of sediment. But geologists know that often in extreme alkaline conditions dead fish can lay on the bottom of lakes and swamps for extended periods of time and not decay away, allowing them to slowly be buried in sediment and later fossilized.