Breccia/Tuff Green-> Red

Many of the rock layers are composed of a breccia of volcanic fragments from earlier parts of the volcano, held together with a matrix of altered ash. The ash is slightly green, reflecting the small divalent iron content. However, when a crack permits hydrothermal oxidation, some of the divalent iron becomes trivalent, and turns from greenish to reddish.


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hhsilleck - Jan 31, 2008 7:06 pm - Voted 10/10


And interesting - thanks for posting this!


MoapaPk - Jan 31, 2008 8:33 pm - Hasn't voted

Re: Cool!

Occasionally, it's nice to see examples of the stuff we've been taught!

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