The letters pages of NCGT journal are always interesting. In the September issue (2015) www.ncgt.org/newsletter.php … Peter James, geologist, has a pop at the current mainstream idea that the dinosaurs were wiped out by an asteroid strike, written a touch tongue in cheek but offering up some criticism of a Catastrophist theory that is now embedded in consensus science. He offers up an alternative catastrophist scenario.
The discovery of a second iridium horizon at, or close to, the K/T boundary is the main evidence for an asteroid strike. Iridium, the argumnet goes, is rare on Earth, but is found in meteorites. Hence, after a major impact, iridium would be part of the vast dust cloud encircling the Earth and gradually, over time, the contents of that cloud would separate out and settle (on the surface). Iridium is heavier than gold and so is amenable to distinctive aeolian and alluvial deposition.
Against this model is an iridium horizon at the K/T boundary in Texas – which exhibits no evidence of extinction (SAharp and Ward, 1991). There was an extinction event at the site in Texas but it is dated several thousand years prior to the K/T boundary event, and another one occurred afterwards.They are both accompanied by evidence of distinct sea level change.
The above could just be an outcome of faulty dating and the assumption that geological layers are always laid down slowly. If the geology was instantaneous it is quite possible they were all contemporary – and the radical shift in sea levels.
Iridium is rare on Earth but it is found in lava flows. The huge basalt intrusion of the Deccan Traps (last week there was a paper that dated these contemporary with K/T) have been offered up as the origin of iridiium at this time. There has even been an attempt to define the Chicxulub feature in Yucatan as natural (Bridge, 2004). Obvioulsy, we are not keeping up here at SIS as the K/T event is the first major catastrophe with a cosmic origin to be accepted by mainstream – and people are chipping away all the time.
Iridium occurs naturally in platinum and osmiridium and has been obtained from gold panning (washing) in the Urals, Australia, Brazil and Canada. Like gold iridium can be concentrated in placer deposits and has been mined in Tasmania and at Sudbury in Ontario. The Sudbury site is defined as an impact site and James admits this is not supporting his argument – but he carries on regardless.
James then says that abyssal fan deposits in the Bay of Bengal are Cretaceous in age, the first of four massive strata of deposition. This indicates there was a dry floor on the Bay of Bengal at the time of deposition of the abyssal fan system which was confirmed by a borehole. Cretaceous muds were found that had dried out (they had cracks within them). In the Atlantic, NW of Africa, another borehole encountered Cretaceous anhydrites. Confirmation of a dry Atlantic sea bed comes from an abyssal fan in the Congo region. James says that massive and prolonged sea level changes are indicated, though not necessary on a contemporary basis as the Cretaceous is spread over 80 million years. He then makes the point if thee was low sea levels in one part of the world there must have been high sea levels elsewhere – which seems logical (unless there was so much evaporation during the K/T event that seas shrank for a time). He says that high and low sea levels are caused by polar wander – although he has not demonstrated where the high sea levels were.
Massive redistribution of the oceans are inferred by the Cretaceous geology, he claims, and this in itself provides an alternative mechansm for the demise of the dinosaurs. For example, birds, amphibians, and small mammals living well above sea level would have a better chance of surviving than the dinosaurs. So, what he is sayhing is that an asteroid strike by itself may not have led to the demise of the dinosaurs but the fact that the earth moved at the poles, leading to a redistribution of the oceans, was a major factor in their disappearance- including their burial in sediments that were caused by the changes, swamped and rolled in water and mud and sand etc.