[Rockhounds] Something going on in Yellowstone

Thu Jan 1 06:27:51 PST 2009

I'm the original not expert.  I learn something totally new about it every five minutes.   I did learn in teh course of reading through some of that stuff that apparently the basalt flows predate the hot spot eruptions, some ancient - shield volcano?   

I've no idea when such a thing happened in North America.    And to be more confusing I got the impression that there were more ordinary eruptions before that happened.   Not Earth didn't have an entire history before teh end-Permian extinction, and there was a smaller flood basalt eruption in India at the end of the Cretaceous, but I keep thinking that a flood basalt eruption in North America must coincide with the development of the crust itself if I never heard of it before.   

But it sounds like you're not familiar with the Yellowstone caldera at all.    This is a very different type of volcano, and they only came to understand it since I graduated from college 30 years ago.    VERY recent.  Hah, hah, hah.    Santorini, the volcano that may be associated with the Exodus phonemena, was of this sort, and so was the eruption of Toba in the Phillippines 75,000 years ago that brought the human race to the brink of extinction.   Not a flood basalt, but the next biggest monster.    Sometimes very thick magma builds up in a huge, abscess-like crater underground under such conditions that it can't easily erupt to the surface.    When it does that's a problem enough - you get pyroclastic flows and ash clouds that travel some little distance.   Like in Pompeii, and Mt. St. Helen's.      But large caldera volcanoes erupt rarely and alter Earth's history when they happen.    If Yellowstone blew it would kill all life on half the North American continent and the climate changes would  starve nearly everyone else on the planet.    Problem is it's due to blow and pressure is building up, and noone knows how much pressure has to build up or what it all means.   The cycle of that volcano is in hundreds of thousands of years - not our time scale.    Confusing the issue is that the volcano is caused by a hole in the Earth's crust that moves over time, relative to I think the North American plate.  Unfortunately it hasn't at this time moved out from under the last caldera, but it does appear to have moved in a direction consistent with its previous movement.   If the volcano significantly changed its geology it could conceivably begin to erupt less violently.  Though part of the violence is due to the nature of the magma rather than the hard cap formed by the previous eruption.   

Several years ago I got interested and put together a web page.   http://www.tiggernut24.com/catastrophes.html   There's an associated page on teh geology of Sumatra and subduction faults that isn't relevant to much that goes on in North America (except in teh Cascades).   http://www.tiggernut24.com/earthquake.html   I begin with a link to the web pages of a PBS special a few years ago.   And the Wikipedia article, and some general geology of hot spots and caldera volcanos.

One thing that complicates the issue is that between the monster eruptions every 600,000 to 700,000 years, Yellowstone does have smaller and more normal eruptions, and these have left more routine lava flows in the area.   I'm not yet up on what kinds of volcano flows leave what kinds of lava deposits, and it's very relevant to understanding Yellowstone.   I thought people here would know that.   On my web site I also have links to some new technical papers that ought to include that information.    

Yours,
Dora Smith
Austin, TX
tiggernut24 at yahoo.com
  ----- Original Message ----- 
  From: J Bryan Kramer 
  To: Dora Smith ; Rockhounds at drizzle.com: A mailing list for rock and gem collectors 
  Sent: Wednesday, December 31, 2008 7:11 PM
  Subject: Re: [Rockhounds] Something going on in Yellowstone

  Were the Yellowstone flows of the flood basalt type or did it build up an actual large dome and erupt from there? I had the impression that these were fissure type eruptions.

  BK

  On Wed, Dec 31, 2008 at 19:06, Dora Smith <tiggernut24 at yahoo.com> wrote:

    OK, my site is fixed.   http://www.tiggernut24.com/catastrophes.html

    I bet there are people here who might have an idea what to make of this.

    I incorporated some maps on my web site.   The bulge and the earthquakes are occuring in and immediately around the northern part of the lake.   Well, the bulge may be bigger, but taht seems to be where it's gotten attention.

    One of the maps shows the location of previous lava flows, as indicated by two types of volcanic rock.

    The danger of a caldera volcano, and the reason why pressure builds up to massive proportions, is typically the layer of hard volcanic rock over teh caldera.

    Now, I don't know if there is in fact no volcanic rock wehre the lake is. The entire area where teh bulge and the quakes are is within the caldera. Which suggests that it should be covered with volcanic rock.   However, if you notice, they are not where the rhyolite is.

    None of it is where the basalt is; it's as if the most recent and largest eruption didn't do basalt.

    Comments, anyone?

    I added some new links to newer technical papers about the caldera and its behavior to my site.   (I also added a link to the Wikipedia article and fixed three links to one web site that moved.)

    Yours,
    Dora Smith
    Austin, TX
    tiggernut24 at yahoo.com

    ----- Original Message ----- From: "J Bryan Kramer" <codeburner at gmail.com>
    To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" <rockhounds at lists.drizzle.com>
    Sent: Wednesday, December 31, 2008 12:35 PM
    Subject: [Rockhounds] Something going on in Yellowstone

    About 60 km down:

    <http://www.seis.utah.edu/req2webdir/recenteqs/Maps/Yellowstone_full.html>

    I've seen some over-heated articles about the supervolcano erupting but it's
    a bit early to worry about that.

    BK

    -- 

    ""It often seems to me that the night is much more alive and richly colored
    than the day."

                        Vincent van Gogh
    J Bryan Krämer
    North Florida, USA
    photos at:
    http://pbase.com/photoburner

    --- StripMime Report -- processed MIME parts ---
    multipart/alternative
     text/plain (text body -- kept)
     text/html
    ---
    -- 
    _______________________________________________
    Rockhounds at drizzle Mailing List
    Subscription Services:
    http://lists.drizzle.com/mailman/listinfo/rockhounds
    List Home Page, with a link to the List Usage Policy:
    http://www.eclecticlapidary.com/Rockhounds/index.html 
    -- 
    _______________________________________________
    Rockhounds at drizzle Mailing List
    Subscription Services:
    http://lists.drizzle.com/mailman/listinfo/rockhounds
    List Home Page, with a link to the List Usage Policy:
    http://www.eclecticlapidary.com/Rockhounds/index.html

  -- 

  ""It often seems to me that the night is much more alive and richly colored than the day."

                        Vincent van Gogh
  J Bryan Krämer
  North Florida, USA
  photos at:
  http://pbase.com/photoburner

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
---