I have just read a large portion of this interesting article that is highly referenced to actual geologic journals. It goes into the deficiencies of current theories regarding the formation of cratons and the crust in general. It then presents the theory that meteorite impacts were the mechanism by which the ancient cratons were formed. I would like the opinions of Pressie, RoxRKool and Petrophysics1 on this. Dr Adequate's opinion would also be welcomed since he has quite a bit of knowledge in geology.
Okay, I can see a few problems with that. One is that Fischer doesn't seem to know the meanings of the words he's using. For example, he glosses the phrase "positive gravity anomalies" with the unhelpful note "(sinking)". That's not what "positive gravitational anomaly" means.
One odd feature of the webpage is that much of it is a vast wall of quotes and paraphrases with no indication whatsoever as to what he thinks their significance are; whether they are meant to be in favor of "Shock Dynamics", or against plate tectonics, or what conceivable relevance they have to either. He does explain that the most important things are in red. Looking only at those, one is again unable to see a common theme narrower than "geology".
There's about 5,300 words of this rambling preamble without one word of what his hypothesis is or how any of his excerpts relates to it.
We then get a scant 800 words saying what "Shock Dynamics" is, with no mention of how it could conceivably relate to any of the observations made. And when I say 800, I'm being generous, because 200 words of that is another block of quotation with no indication of its relevance.
And then there's about 400 words of creationist nonsense about radiometric dating, consisting of a string of quotations from a most scholarly work, wait, I'll read that again, crudbucket, entitled Shattering the Myths of Darwinism. As the author doesn't say why they're there, I am unable to conjecture.
So we've got about 600 words telling us what Shock Dynamics is, in the vaguest possible terms, and nothing at all to explain why we should think that it's right. There's no model, there's no predictive power, there's just a set of odd assertions.
There's not even much of an attempt to make his ideas look explanatory. How, for example, does he explain subduction zones?
Like this: "The leading edges of moving continents produce thick lithosphere, mountains, and benioff ("subduction") zones; shock waves in the crust freeze at the threshold energy level, forming "subduction zones" in oceanic lithosphere."
Does that give you a picture, even a vague one, of what causes the earthquakes in a Benioff zone? Are they caused somehow by this frozen shock wave of which he speaks? How?
So we have what cranks usually come up with, an idea for an idea, the sort of thing one might think of in one's bath. Fischer simply hasn't tried to develop the idea sufficiently that one could relate it to the evidence. He has disguised this fact (possibly from himself) by producing his Big Wall O' Quotations. That is certainly a lot of evidence for ... something ... perhaps the proposition that geologists write a lot of papers, or that the Fischer knows how to copy and paste, but there's no attempt to relate it to his ideas --- for over 5,000 words, he produces slab after slab of this stuff without mentioning "Shock Dynamics", let alone mentioning how the facts he cites could possibly relate to it one way or the other.
Let me give you an example. One thing he puts in red as being "most important for the new interpretation" is the phrase "the Tanzanian craton is unique". Looking at the surrounding context, which explains why it is unique (and which was not worthy of highlighting in red) we find that it is unique in that it has a "dramatic excursion to β=4.20+0.05 km/s at 200-250 km".
Now, Fischer's hypothesis, let's remind ourselves, is that: "The continental crust itself was likely formed by the grazing collision of a planetesimal with Earth. The differentiation and fractionation of the mantle allowed the lighter elements to rise to the top and solidify as a single "scab" of continental crust." Is there anything in that that suggests that the Tanzanian craton should be unique, either in possessing a "dramatic excursion" or in any other way? You can't see the connection, I can't see the connection, and if the author can see the connection he is curiously coy about mentioning it. So why is it "most important for the new interpretation"? Or even of tangential relevance to it?
What Fischer needs is an actual model. He should say how big the planetesimal was, how dense it was, how glancing the blow was, and when it hit; and he should say what the Earth was like before it hit. Then he should use the known laws of physics and chemistry to model the results of such a collision. And then he would have predictions which he could compare to observation. And then he would be doing science. As it is, he's just pretending to be doing science. I don't mean to impute deliberate deceit, it is very likely that he has fooled himself into thinking that he's doing science. But he is not.
I guess I didn't read it that carefully. Now, I am embarrassed. I didn't realize he was a creationist. I didn't read the part where he took on radiometric dating. I was just fascinated by reading the various problems like the preservation of cratonic keels in the presence of mantle convection. I thought with all the references, it had to be something serious. My apologies.
I thought with all the references, it had to be something serious.
No need to apologize. The references appear to be related to issues the author cites with conventional geology. They are not totally useless.
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I would say here something that was heard from an ecclesiastic of the most eminent degree; ‘That the intention of the Holy Ghost is to teach us how one goes to heaven, not how the heaven goes.’ Galileo Galilei 1615.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
The Limpopo Belt is located in South Africa and Zimbabwe, runs E-NE, and joins the Kaapvaal craton to the south with the Zimbabwe craton to the north. The belt is of high-grade metamorphic rocks that have undergone a long cycle of metamorphism and deformation that ended 2.0 billion years ago, after the stabilisation of the adjacent massifs. The belt comprises 3 components: the Central Zone, the North Marginal Zone and the South Marginal Zone.
Cratons are not necessarily the oldest parts of continents. It's very old news.
If you want to read and can get hold of it, try:
South African Committee of Stratigraphy (SACS), 1980. Stratigraphy of South Africa,. Part 1. (Comp. L.E. Kent). Lithostratigraphy of the Republic of South Africa, Southwest Africa (Namibia) and the Republics of Bophuthatswana, Transkei and Venda: Handb. geol. Surv. S. Africa., 8.
In chapter 2 (pages 19 to 23), this is discussed and they provide a whole list of references to peer-reviewed, published articles on how the ages were determined.
The creationist writer you referred to is setting up a straw man.
Be careful what you read and believe on the net. It provides a platform for lots of nut cases to vent their crazy ideas by sugarcoating it with references to real research, pretending that legit research support crazy ideas.
It certainly shows he was not careful with his statements. He probably had no idea that the Limpopo Belt was older than the Kaapvaal Craton. This means that there was an older landmass that formed the Limpopo Belt that has since eroded away. It is easier reading the net articles than it is reading the actual literature in many cases. The literature seems to be written by PhD's many times and contains technical language I have never encountered. But, as you said, you run the risk of coming across nutcases because anyone can say anything they want on the net.
I didn't mean the belt eroded away. I meant that the landmass or craton that created the belt eroded away. Since it is made of highly metamorphosed material, something had to push against it horizontally a long time ago.