Friday, December 6, 2013

Answer: Part 2 -- what are the Popo lava domes made of?

Fred pointed out that I left out one of my questions.  (This is what comes of trying to get it done by 5PM EST!)  

To complete the question about the what the lava domes are made-of, I went to Google Scholar and did the straightforward query: 

    [ Popocatepetl lava dome ] 

And to learn a bit about the lava domes, I skimmed the first three papers.  In the third paper (Popocatépetl’s crater filled to the brim: Significance for hazard evaluationI found the phrase, "dacite lava domes."  

Since I had no idea what "dacite" was, I did: 

     [ define dacite ] 

where I learned that dacite is a volcanic rock resembling andesite but containing free quartz.  

From Wikipedia I learned that "... Dacite consists mostly of plagioclase feldspar with biotite, hornblende, and pyroxene (augite and/or enstatite). It has quartz as rounded, corroded phenocrysts, or as an element of the ground-mass." 

And yes, I looked up all of those words.  

But in the end, it's a pretty generic igneous rock spewed from volcanos of this type.  It's key feature for lava domes is that it's reasonably plastic, so as gas bubbles up from below, the cooling dacite forms bubbles that appear as domes in the caldera.  

And that's what the domes are made of.... 


  1. Fred you don’t miss a beat. Finding the right term can be a challenge. Here’s Google’s definition [define caldera volcano] is “A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption. They are sometimes confused with volcanic craters. The word comes from Spanish caldera, and this from Latin CALDARIA, meaning "cooking pot". …

    I think you may be referring to the dome which is a ‘lava dome’ according to the
    New Scientist article

    I enjoyed looking at this student site Thinkquest showing us types of volcanos, structures and a section on calderas and crater lakes. I’m impressed with the details and simplicity.

    Fred & Ramon I think you have taken search results to a new level. It's great doing these searches with you. I learn from your posts as well. Have a great weekend.

  2. Fred, good eyes! I didn´t see that the question was missing.

    This part of challenge is very interesting and with lots of unknown topics like Dr. Russell and Rosemary mentions. I thought that was only kind of material and eruption type. And also didn´t know the words that mentions Dr. Russell.

    So, I did another SearchResearch ][ kinds of volcanic eruptions The one that sent the mudflows is Plinian

    Also found with [Popocatepetl kind of eruptions Volcano World Oregon State :Popocatepetl lots of information and links to other sites like Google Scholar and Michigan Technological University Volcanoes Page that has very good information about volcanoes.

    Hope Remmij is ok, since this week didn´t post.

    Finally, out of topic, one good topic for a future Challenge could be the History of "Taxi".