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Not my area unfortunately, the Yucatan crater has now been in part ruled out being behind the KT boundary (these been at least one Horizon program on the matter), but its still highly contentious.

wiki provides a pretty good summary of the current state of play
http://en.wikipedia.org/wiki/Kt_boundary

I don't think the KT boundary is a good example for your needs, not least there is alot of debate over it, including whether or not it actually did for the dinosaurs. Extinction events in the geological past are generally poorly understood and are amongst the most hotly argued topics.

Predictions in geology are seldom cut and dried, as with the KT boundary, or tend to relatively obscure for example it has been possible to identify specific types of sedimentary structures in modern environments and then find then in the geological record. Geology is perhaps more than any other science dependant on uniformatirianism, which explains creationist geologists masking their often poor geology with shouts of "uniformatarianism is a bad assumption". Any half decent geologist knows that the concept of unformitarianism is a tool like any other and must be used with some dissercernment. During periods of the Earths history there have been continent shelf seas quite unlike anything we see on the planet today. While fundamental processes remain the same we would be quite foolish to assume that those seas functioned in the same way as our current rather narrow continental shelf seas.

When you talk about the Tiktaalik, it is not as such a predicted I would argue - rather paleontologists now target those periods of geological history with a currently poor fossil record, looking for so-called transitional forms inparticular. We know those forms MUST have existed, its just a matter of finding them (if of course any survive to be found (the geological record is far from kind)). We can't really as such "predict" the existance of a particular species rather paleontologists can make assumptions on what they may be like based on older and younger forms so far found.

Yeah, Tiktaalik was verifiable but not falsifiable. A weak confirmation - but still confirmation. Stuff like that is still good.

Will definitely read up on sequence stratigraphy - I don't know nearly enough about the geological science. I'd say that this is the one solitary benefit of arguing with creationists - it gets you one hell of a general science education.

Walter Alvarez's book T rex and the Crater of Doom is a good easy read on this issue but is a bit out of date - we now know that there were at least two other impacts at the same time. There also remain some questions about the Deccan Traps, IIRC and thers is also stil a debate as to whether the impact caused the K/T boundary (Keller et al argue that the Chixculub crater was fprmed 300,000 years before the K/T boundary).

There were several features of the K/T boundary which pointed to the impact including loss/change of fossil record, high levels of Iridium, the presence of spherules and a severe thinning out of foraminifera. The hunt began to center on the Carribean after the discovery of sediments that appeared to have been laid down by a Tsunami(s) and thick layers of impact debris.

It was a great piece of detective work capped off by the Shoemaker Levy comet.

Roger

I checked this out about six months ago. Keller's work which suggets that the impact was 300,000 years before the K/T boundary is highly contentious and big egos being what they are, her position has been described as one of sour grapes.

Well, I just thought of another one that may help but I am no expert on it whatsosever.

That is the formation of the land bridge between North and South America about 5 million years go.

This appears to have led to a mass migration of species from North to South America and extinction of most of the marsupials there as they got replace by basically cleverer mammals filing the same ecological niche (Gould did work in this IIRC).

Moreover, my understanding is that the land bridge is quite widely believed to be the primary or one of the major causes of the ice age as it changed oceanic flows beteen the Atlantic and the Pacific dramatically. Lots, there, also which impacts on our understanding of the facts of evolution.

Roger

Species spread is probably quite a good example, though not strickly geology.

As for reading up on geology, I can't really recommend any good generalist texts, I'm afraid. It is also worth bearing in mind that geology has a touch of an "art" to it especially when it come to field observations and there interpretation. So far the quality of the field observations in the creationist geology papers I've read is decidly sketchy, but I'd caution arguing the toss on such things unless you know exactly what your looking at!

The old adage that a little knowlege can be a dangerous thing was illustrated by some creationist taking the developement of a land bridge, with an apparently climate-benifiting change in ocean currents, as being an example of intelligent design of the Earth (I think it may even have been the one Roger talks about)!

Yes and no. Basically geologists are not that interested in the diffusion of mammals or other vertibrates.

Generally geologists see paleontology as a means to an end and it isn't biology - it's dating of strata. Therefore they are far more interested in how common a species/family etc is than its biological significance. The more common, the more useful and, thus, as a generalisation, the smaller the better. IIRC by the 1950s microfossils had become the major area of interest of geologists and even before that much of it was dull stuff such as brachiopods and belemnites. Stegosuars, T rex - forget it.

I supose that the geological/fossil evidence of the spread of placental mammals and the decline of marsupials in South America is of general significance to geologists but, for the most part, geologists in the field ain't interested. They don't show where the minerals are.

In a sense, geology is an applied science which draws heavily upon all three major pure science disciplines - physics, chemistry and biology. It also very heavily overlaps with physical geography.

One of the areas I am looking at is how fossilisation takes place - the fundies don't get it because it requires a pretty good understanding of chemistry. Seems to me that knowledge of the pure sciences is a pretty good start in pulling to pieces fundamentalist crapola about geology.

And, of course, you always have Andrew Snelling to show to the world as an example of a fundamentalist geologist who is a complete fraud. I think I have already satirised him in this group. If not, let me know.

You dont need to satarize Snelling or any other YEC "gewologist" - just give straight reporting!

Quite right, Michael.

Sometimes, you just can't make this stuff up.

You obviously don't know that fosillisation can take place pretty quickly Roger:

http://www.creationtruthministries.org/newsstore.html

Seriously though, isn't the impact theory as the cause of the KT boundry just one school of thought ? Iridium is also present in magma and I think some geologists wreckon that it was increased volcanic activity that caused the mass extinction. Whatever the reason, I think there are misconceptions about the event. The deposit doesn't indicate something that happened overnight, but rather, an occurance that took place over quite a long period of time.It was sudden in geological terms !

You obviously don't know that fosillisation can take place pretty quickly Roger:

http://www.creationtruthministries.org/newsstore.html

Seriously though, isn't the impact theory as the cause of the KT boundry just one school of thought ? Iridium is also present in magma and I think some geologists wreckon that it was increased volcanic activity that caused the mass extinction. Whatever the reason, I think there are misconceptions about the event. The deposit doesn't indicate something that happened overnight, but rather, an occurance that took place over quite a long period of time.It was sudden in geological terms !

Yep, the Chixculub thingie is not straightforward at all. My understanding is that Kellr leads the pack claiming that there is a 300,000 year gap between the impact and the K/T Boundary which suggests that another, unidentified, Bolide impact did it. However, the original team that put together the Chixulub theory vigouroulsy defends the original model. The Dutch geologist Jan Smit (spelling??) is amongst the leaders of this pack.

The theory that volcanic activity was the cause of the mass extinction is somewhat more complex and, IIRC, centres on the Deccan Traps. There was/is a theory that the Deccan Traps activity was the result of the Chixulub impact (there may be a large impact cratar off the west coast of India). However, the Deccan traps outflows took place over several million years.

It seems to me that the issue is actually more complex than this in that the dinosaurs were on the decline before Chixulub. That was documented before Alvarez et al put together the impact theory. Any idea what the position was with other groups that became extinct such as ammonites or the microfossils that make up chalk?

From memory, the Alvarez evidence of a sudden formation of the K/T Boundary was based on two sets of evidence - the boundary well away from the impact zone which appears to be largely if not wholly the result of stuff that came through the atmosphere and stuff much closer which is much thicker and appears to be the result of tsunamis and flooding. However, IIRC, there were some big problems in understanding what the nature of deposits resulting from Tsunami looked liked. There wasn't much geological knowledge of them 15-20 years ago.

I also suspect that there may be a flaw in the interpretation of the thickness of the K/T Boundary deposit. With multiple impacts at the same time (one appears to have been off what is now the East Coast of England), thickness would not be neatly correlated to distance from Chixulub.

The Creation Truth Ministries "fossilisation" of teddy bears is played on by John Mackay. As I pointed out early, it is something I am trying to pull to pieces but I don't have the knowledge of the chemistry of fossilisation.

My understanding is that in the process of permineralisation rather than petrification, the bone material (of dinosaurs) does not, as such, survive because it is subject to substantial chemical alteration (as distinct from absolute replacement). Vance Nelson and Mackay are being ingenious to suggest otherwise.

All Nelson is doing with his damned teddy bears trick is demonstrating simple chemistry that can be recreated in the school lab or on the kitchen table by a moderately bright school child. It is a pity that no one has pulled to pieces the Nelson/Mackay trick.

The other bit of info I can't find is where Vance Nelson got his degree in biology from. Like most of us, I always question the status of the claimed qualifications of creationists. Any ideas about Nelson's degree anyone?

Roger

Fundamentally you are correct in the that any bone, shell or similar material does not ultimately surivive fossilisation (in most cases). A quick scour of my old paelontology notes dug up the following:

Preservation of fossils can occur in four basic ways:
1. Unaltered - this requires the entombment of the animal in amber, tundra or tar
2. The fossil is preserved by any of the following three basic mechanisms
[a] Compression, the animal is carbonised
[b] Recrystallisation - this produces a what is known as a paramorph fossil by the direct change of one mineral form to another form.
[c] Replacement - this process sees the replacement of one mineral by another.
3. Moulds - these can either be internal or external, or both, internal moulds may be either be formed from trapped sediment or by minerals precipitated from sub-surface fluids.
4. Trace fossils - preserved track ways and burrows.

Methods 1 & 2 produce "body fossils" while 3 & 4 produce what is known as "traces of life" from which the presence of life can be inferred. As a side note technically human artifacts, ie flint tools, are not fossils.

Technically Mackay's teddy bear would probably be classed as entombment, as if you break it open the bear will remain inside (especially if it made from synthetic material). Cotton or similar fabrics may rot over the time required for petrification as it is not quite as instaneous as say entrapping in amber. Fossilisation therefore can occur very rapidly (an understood and accepted part of mainstream science) - however in the majority of cases it occurs very slowly! Petrification wells occur in only very specific places because of the high levels calcium carbonate the waters must contain. They do represent the general condition of ground waters at depth.