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Wednesday, November 14, 2012

Iron, man!



The various layers of rock in the cliffs of Bell Island indicate that they are sedimentary in nature, composed of brownish grey shales and sandstones.  But, interbedded are beds of hematite iron ore.  That's an interesting relationship because sandstones and shales are formed by the mechanical transportation of sand and clay grains.  Hematite is too heavy to be transported any distance.  It has another origin.


In September I got out to explore this bed of hematite that had been mined on the west side of Bell Island.  The iron ore here had a substantial thickness.  So, how did it form?

Well, the iron ore had a chemical origin.  Hundreds of millions of years ago in the Ordovician geologic period the oceans at a time were anoxic, that is, there was very little oxygen in the water.  That was caused by widespread glaciation.

Along with the dissolved minerals that makes the sea salty, ferrous oxide (FeO) was in suspension.  As the climate warmed, glaciers melted and photosynthesis resumed and the oceans became more oxygenated.  The ferrous oxide reacted with the introduced oxygen to create the new compound ferric oxide (Fe2O3) which settled to the sea floor and formed these iron ore beds.

Interesting or what?  I think so. 

2 comments:

  1. Hi Tony - I'm researching a trip to NewFoundland in 2013 - Just started looking into things - I wonder if you could point me in the direction of a good place to hire 4 decent boats - any of the usual British manufacturers would be suitable - Rockpool, Valley, P&H etc.
    Many thanks
    Will

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  2. Will, mail me a my gmail account: kuviasuktok@gmail.com and I'll send you my private email address to pass along along the info you are looking for. I don't use my gmail account much so I don't care if I get spammed there by making it public.

    I can assure you that you won't be disappointed with a visit here.

    Tony :-)

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