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Salt glaciers

2 April 2013

In the Zagros mountains of Iran salt domes, a quite common geological oddity, break the surface – see http://geology.com/stories/13/salt-glacier/

As the region is arid there is not enough rainfall to dissolve the salt and wash it away, and instead, salt moves enmasse down the slope, just like an ice glacier. Salt domes form where a layer of salt is buried under sedimentary material (that goes on to become a rock formation). The article does not mention the origin of the salt – from sea water perhaps, as a result of evaporation (suggesting a lot of heat was involved, and if laid down quickly, a lot of heat over a short period). Salt as a geological layer tends to date from way back, such as the Triassic (back in the dinosaur period) or the early Tertiary. A buried salt glacier has actually been found in Germany indicating the climate at the time must have been somewhat akin to present day Iran, too arid to dissolve the salt.

At http://phys.org/print283951621.html … brings to  life the fact that geology is able to show past climate change and past earth changes. However, it seems the Earth is the only planet in our solar system in which Plate Tectonics is taking place. Should that sound alarm bells?

It is assumed new crust is welling up in mid-ocean, solidifying to form new sea bed floors. In other regions the hypothesis supposes other pieces of sea floor or plate material is being subducted, diving into the interior – all the way into the Mantle. Again, computer simulations are used to show all this happening – on screen. Does it really happen in the real world?

Plate Tectonics is perceived as a slow process, centi-metre by centi-metre of movement (a calculation rather than an observation) causing earth changes over hundreds of thousands of years. However, not all subducting plates are behaving in the way the theory has mapped the process and this has to be explained within the hypothesis (the consensus will be defended until it reaches a point of indefensibility) and a paper in Nature Geoscience puts the problems down to congestion. Lots of subducting material is queuing up to move underground. Presumably models have again been used to sift the data and the word congestion seems to have been hijacked to explain 'its not happening here, but it should …'.

On the other hand why should the subduction process take place at a uniform rate everywhere in the world. In some regions it may take place at a slower rate than in others, and yet, have all the subduction zones been checked out to see if this 'congestion' is taking place more commonly, or is this a situation where one geographical location has been looked at in relative isolation?

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