The Bahamas Platform

25 July 2014
Geology

Uniformitarian geology is both weird and wonderful – at the same time. Gary Gilligan has sent in a link to www.dailymail.co.uk/sciencetech/article-2705916/Was-Bahamas-created-Saha… … which begins, the Bahamas may have its origins in iron rich dust blown over from the Sahara desert. Well, a lot of dust does blow in that direction – and across southern Europe (and northern Europe less so). However, the Sahara was not a desert prior to 5000 years ago – so what is going on. Well, the wonderful bounty of uniformitarian deep time. The higher rainfall levels in the Early Holocene are thought to have an origin in Milankovitch cycles. Hence, wet today and dry tomorrow – over and over again, all the way back to the Dinosaur Age (as this is where all this takes us, the origins of the Bahamas platform, currently mostly under water but above sea level during the Late Pleistocene). What is not said, by the Daily Mail at least, is that in the Dinosaur Age the Atlantic was a much narrower affair, a so called shallow sea basin. It is unclear if this effects the basic research but as always, what is not said is often as important as what is said.  In Plate Tectonics the Atlantic would have gradually widened over the course of time throughout the Tertiary Period. In the Expanding Earth theory the platform is a bit of crust that got stranded off the coast of America – and its origin may be quite unremarkable (in spite of what will subsequently be related).

Firstly, there is the supposition that the Sahara existed, if only off and on, over millions and millions of years – but what exactly was found? It seems that two trace elements characteristic of atmospheric dust, iron and manganese, are plentiful in the geology of the Bahamas platform. Some 270 samples were taken so it was pretty thorough. The Sahara is currently a major source of mineral dust, blowing across the Atlantic. The argument revolves around 'whitings' which appear to be white sediment laden bodies of water produced by cyanobacteria. It contains ten times more iron than other photo synthesizers because they are able to influence atmospheric nitrogen, it is alleged. The argument continues by saying the process draws down carbon dioxide and induces the precipitation of calcium carbonate (creating the whiting effect). It all sounds a bit like the origin of chalk – from fossilised algaic blooms in sea water. The platform is therefore made of a material that blossomed as a result of lots of nitrogen and iron – but does this necessary have a connection with the Sahara. The answer to that is 'may be, perhaps …'. It seems a long shot. Notice the inclusion of carbon dioxide. All we can say is, nice theory. Iron and nitrogen could alternatively have an origin in space – ending up in the atmosphere of the Earth. Let's not forget the Dinosaur Age ended with a big bang – an impact event not very far from the Bahamas.

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