Extremities:  Geology and Life in Yellowstone and Implications for Other Worlds


We also took reflectance spectra of other microbial mat samples we had collected (with National Park permission) in Yellowstone.

Nymph Creek Mat Spectrum


TB View Springs Mat

Cyanidium mats from the highly acidic waters of Nymph Creek appear bright green, although they do not show much difference in reflectance between green light wavelengths and blue or red. This spectrum is characteristic of chlorophyll b. The "mat top" spectrum was taken by Gloria, Joan, and Scott. The repeat spectrum was by Allan.


The TB View Spring at Mammoth Springs had relatively cool water rich in sulfur. Bright green Chlorobium tepidum mats of grow in its waters, and their reflectance spectrum is charcteristic of bacteriochlorophyll c, similar to the spectra of the Octopus Springs mat top. Spectrum taken by Lana and Phyllis.




New Pit Purple


Dry Valley Mat

The New Pit in the Mammoth Springs has mats of the purple sulfur microbe Chromatium. Unfortunately, by the time we got to measure its spectrum, it was all brown. The reflectance spectrum of it is brown: little blue, and more red than green. The low reflectanced at about 750 nm is consistent with bacteriochlorophyll a. Spectrum measured by Susan and Marilynn.


Christine Foreman provided a dessicated sample of a microbial mat from the Dry Valleys of Antarctica. The sample was gray-brown, with a hint of green. The reflectance spectrum (measured by Pam) is nearly featureless, but the slight increase in reflectance at 585 nm and the decrease around 650 nm can be ascribed to chlorophyll b. If this mat were on Mars, it might be very difficult to distinguish it from a gray green rock (i.e., from the great gray green greasy Limpopo River, all set about with fever trees).

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