10 Comments

A rock composed of mineral dolomite ought to be dolomitite surely?

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:) Ha ha! "Dolostone" as an analog to "limestone" would be fine with me, but there's no real consistency in use that I've seen (and I guarantee I say "dolomite" for the rock, too).

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EXCELLENT -- what a braid of history!

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Also on the expedition to Egypt, and suffering a similar fate as Dolomieu, was General Thomas-Alexander Dumas, leader of some of Napoleon's troops. He was the father of the famous novelist. His story is told in: https://en.wikipedia.org/wiki/The_Black_Count:_Glory,_Revolution,_Betrayal,_and_the_Real_Count_of_Monte_Cristo. It provides an interesting look into slavery on Sant-Domingue, the French Revolution, and Napoleon.

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Thanks Tom, yes, Dumas and Dolomieu were on the same ship that was forced by storms to land at Taranto where they were both incarcerated.

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Last sentence was meant to say "..or if the rocks formed as limestone.....

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As always, very interesting. I was wondering why many of the Proterozoic carbonate formations are often dolomite (dolostone) rather than limestone (e.g. the Pahrump Group in southern Death Valley) . Was wondering if the formations were deposited as dolomite due to the geochemical conditions at the time, or if the rocks formed as dolomite and underwent replacement?

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Well, there's the question!! I don't think I've even addressed that (I was a little afraid to try). I guess if you could find evidence of sabkha-like environments, or at least varying shallow water, the new explanation for primary dolomite might work. As you know there are plenty of intraformational (edgewise) conglomerates suggesting variably shallow water in the Cambrian Pilgrim dolomites as well as the Devonian Jefferson, so that might work for them. I've always had a problem understanding why, in a local region, some of the carbonates are dolomite and others are not. Hard to explain that as from later pervasive dolomitization. I'm definitely not experienced enough to answer this very good question - but thanks for asking it!

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Dick,

Great bit of history and explanations! May I be a picky and pedantic ex-Prof. and say "formation" should be capitalized in Amsden Formation - as it's a formally recognized stratigraphic unit in the US?

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Certainly. Thanks.

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