Geologists do indeed use fossils to date layers and layers to date fossils. What's wrong with that? I use a clock to set my watch. Both are regulated by a time signal from a radio, generated by an atomic clock, using exactly the same physics that defines radiometric dating, which is used to age date the rocks containing the fossils, in the layers, in the first place.
He's saying my watch is wrong then? He can go screw himself. It cost me $15.99
C14 (carbon dating) is not used to date rocks, because the half life of Carbon 14 is far too short to be useful. That fact alone consigns his entire argument to the wastepaper basket, but he seems unable to see that.
Kitten is the one to ask about this. Much, much (one more time)MUCH longer half lives are required to date real rocks (as opposed to Pleistocene sands, gravels and other gardening related debris).
Google radiometric dating . Or here's a sensible summary
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/clkroc.html
...and a not so sensible example, which does illustrate a valid point.
http://www.answersingenesis.org/articles/am/v1/n1/radioactive-dating
The point is, that over the odd billion years or so, a lot can happen to a rock. It doesn't just sit there. Assuming the laws of physics have not changed (and the OKLO reactor suggests they have not), radioactive decay has always happened at the rates we think it has.
Still there remain many sources of potential inaccuracy, some of them due to problems analysing the samples, some because other assumptions are wrong- most notably that the mineral we are dating has not been altered in some way since formation. (We don't really date rocks. We date minerals in the rocks. It's possible for the radiometric age of the rock and the mineral to be different. Just because you and your dog are in your car does not mean you are all the same age. )
eg a crystal in a lava forms from a chemical melt. Ten days later , another lava pulse partially melts it again. Does this reset the clock? Probably. Well- who cares about ten days over a billion years?
Nobody.
But what if , during the next billion years , our lava is gradually buried five miles deep in an area subject to high geothermal gradient , tectonic overpressure and percolation of water? (That would be superheated steam if not for the pressure). Does this reset mineral radiometric clocks? Did dinosaurs poop in the woods?
Radiometric dating is one tool in the box, but should never be trusted on its own. If only the world was so simple, how easy life would be.
It's necessary to view radiometric dates in the light of the interpreted history of the rock formation.
If you have a pile of rock, the rock on the bottom is older than the rock on the top.
Unless it's inverted.
Do whole mountain chains turn upside down? Darn right they do! And that's another shot in the head for Mr.Hovind. If we accept that radiometric dating is subject to geological interpretation, we must also accept that whole countries have FLOWED like warm toffee, in order to get so distorted that "solid" rock ends up like a concertina the wrong way up.
Rock is not solid. To a geologist, nothing is solid.Only poets think mountains last forever. And ecologists. Ye gods, where do they thing VALLEYS come from?
Where was I?
Rock deforms in a plastic fashion only at incredibly low strain rates. Hit it with a hammer and it shatters. Heat it up and hang a weight from it and guess what? It bends. But you have to wait millions of years before it bends enough to turn a whole country upside down- and of course Mr.Hovind does not have the time. Fortunately, geologists do.
Fossils. These are disgusting things found in sedimentary rocks, which no right thinking geologist gives a damn about anyway, except petroleum geologists who are basically a bunch of wooses.
In the early days of Geology, in the 18th and 19th century, nobody had maps of the geology of anywhere. Mine engineers and the like noticed that some rocks in some parts of the country (mostly Britain) looked the same as rocks elsewhere. Could this help them find coal and stuff? You bet it could.
There were recurrent patterns. There was a grey limestone- (fine building stone. Hadrian used it for the wall)- which was always found
below the beds with coal. No sense looking under the limestone for coal, there was none. Find the limestone, you had to go
up the succession to find coal. Both these formations had fossils, of very different types.
Nowadays we would call the grey stuff a Mississippian Limestone* and the coal and sand "Pennsylvanian" , thus proving god is American. (Grumble , spit! "Carb Limestone and Coal Measures was good enough in my day...")
Anyway. Yes. The fossils identify the layers and the layers are identified by the fossils.
You'll note I say "identify" not "date" . "Date " should be used for radiometric age dating, which , if we ever get it right, will be absolute dating. What's done using fossils is relative age dating. Cambrian is older than Ordovician is older than Silurian. None of this tells us the absolute age of anything. That's what atomic physics is for. Atomic physics works, by the way. Unless the laws of physics have changed since 1945 anyway- but in an age of miracles, who can tell?
*Trivial addendum. Blarney Castle is built of the same stuff, as is half Ireland. Is it possible Kent kissed the Blarney Stone when he was a boy and has had the gift of the gab ever since?
Thanks Zombie.
