Thursday, February 12, 2015

Geo 1095: February 11, Day 772: Stalagmites on a Flowstone Dance Floor

When calcite-saturated water droplets fall from the ceiling, not only can they slowly build stalactites from there, but when they hit the ground, the agitation causes more calcite to precipitate. This leads to the development of stalactites' counterparts, stalagmites. In this case, the slow flow of groundwater is still saturated with enough calcite that it has created a lower, flatter platform of flowstone. The high points on that "dance floor" represent the impact sites of steady drips from the ceiling, while the broad slope is deposition from a thin sheet of run off from those point sources.

The choice of "dance floor," in this case, is chosen for two reasons. First is the simple esthetic imagery: it pleases me to imagine these features dancing over the millennia, at rates so slow, we could never hope to perceive the pattern. The second reason is that they are! Can you spot what I'm talking about? Here's a hint: look for a dark, nearly horizontal (but small) feature near the center of the photo, and try to figure out what it is... Answer in tomorrow's post, which is really today's, since I'm a bit behind. I'm hoping to get it done before I go home tonight.

Photo unmodified. May 9, 2013. FlashEarth Location. (Since we're underground, I have only a vague idea where this is with respect to the surface.)

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