Some 780 million years ago, a massive, singular continent, Rodinia, was being torn apart by convective forces within the Earth. In Glacier National Park this tumultuous event is marked by a thin, dark igneous rock, squirted between layers of limestone, the Purcell Sill, adding favor to Mt. Gould.
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speaking of metamorphosized limestone, i just visited again a site in Sheffield MA, with marble and quartzite intermixed and Tremolite all over the place
horizontal layers (limestone?), light band with vertical collumn like texture, dark basalt with vertical collumn LIKE texture, thin white band, light band with vertical collumn like texture, horizontal layers (limestone)?
hmm