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Posted by Ballpark Frank (69.178.8.75) on 10:21:00 11/21/16
In Reply to: Glad you enjoyed the photos! posted by Granite Head
Granite Head,
Seeing this larger iteration of the photo, I immediately recognized the plates of "calcite ice" laying beneath the hydrothermal flow on the left side of the image are plates of calcite ice. This is a way interesting and under researched feature of Mammoth's springs. Like a number of other features, there appears to be some seasonality, but it is not clear cut. Over the years, I have noticed calcite ice is rarely seen in summer, and more common in the cold months, but it is not so consistent as to constitute a "rule". I've been told that calcite precipitates out of the hydrothermal solution, but the process is poorly understood. Once in a rare while, you will catch it on the surface, but the vast majority of times, I have seen it laying on the bottom of a pool or runoff channel. It appears that some dynamic drives the precipitation out of solution, but eventually, the calcite ice is heavier than the supporting liquid, thus it sinks.
The green substance is significant. There is a good chance it is new colonies of filamentous bacteria. While the green color varies from a pastel lime green to a classic dark green (likely a variant due to concentration), in my experience, Mammoth's springs tend to exhibit an assortment of pastels in the colder months, including lime green, pale yellow, peach, and light shades of purple. In the warmer months, the colors tend to be more mainstream (darker, richer). When I reported this observation to one of the most knowledgeable non-geologists I know at Mammoth, he suggested that when the warm months returned, I look under the boardwalk at areas in the shadows. Sure enough, when the warm weather returned, I laid on the boardwalk in several places, looked underneath, and noticed those pastels so characteristic of winter. My former co-worker's theory is that the color variation is related to abundance of sunlight, which bears on photosynthesis. I didn't think about it at the time, but that "might" explain the lime green as opposed to dark green, but it does not seem to explain the other pastels. Perhaps we have more than one variable at play here, or just one variable that has nothing to do with photosynthesis.
I share your appreciation for these stunning features on the south end of Main Terrace. Over the past 20-30 years, we have been treated to an impressive display of Mammoth's power, thanks to this dynamic assortment of vents and associated runoff channels and pools. I'm grateful for the NPS having periodically rerouted the boardwalk, but not having taken the easy way out, and simply closed access due to public safety concerns, resource protection, or lack of funding.
Ballpark
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