Evidence in the geology - cliffs and varves

Continuing the mini-series on the myth of the flood . . . 

Geologists have search in vain throughout the centuries for evidence of the flood and so far not only have they drawn a blank but they have also found strong evidence against the idea of a single great world-wide flood just a few thousand years ago.

Creationists argue against the science to try to explain these findings in a way that supports their ridiculous story of the literal truth of the Old Testament, but the more they say the more it is obvious that they are clutching at straws.

To paraphrase what a creationist (a nice creationist) told me recently, layered rocks containing fossils can't be 'evidence' of evolution!  They can't be what they seem to be - millions of annual layers - that would make the world look very old!  
Just a minute . . . it actually is very old (at least compared with what the bible says).

Let's take the evidence of the Green River varves as an example.  Wikipedia says:

The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in winter. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.  

England's famous White Cliffs of Dover also represent evidence of a sedimentary structure formed over a period of about 40 million years.   They represent the edge of a 400m thick layer of chalk which stretches across the British Isles to the Antrim coast in Northern Ireland.

Creationists oppose both of these examples, partly on the basis that they prove that the world is over 6000 years old.  

In the former case they suggest that the layers might have been created by individual waves, so instead of representing millions of years of annual cycles they were formed much more quickly.  (Naturally we see structures like this forming all around us all the time don't we?)  In the latter case they say that all this calcium (agreed to be the leftover bony structures from tiny creatures) was the result of a series of 'blooms' of plankton.  I even saw one treatise on the topic claim that it 'only' needed a 500m thick layer of plankton in the sea to produce such a deposit.  (I think that was the whole of the oceans, and somehow the deposits swirled around and landed at Dover.)  They even had an implausible excuse to explain why it was not relevant that the life-forms in the top few metres would completely block out the light from the layers underneath.  Let's just say that I didn't find it convincing.