Monday, August 19, 2013

Wilbur Hot Springs: Geobio scouting expedition

Streamers and exciting mystery crust
On my way out of California, I couldn't resist stopping off for some geobio-tourism. I had heard rumors of some beautiful mats at some sulfur springs somewhere within a day's drive of Chico, and when I checked in with Russell, next thing I knew we had a field trip planned.

The site was Wilbur Hot Springs, site of a beautiful, historic, clothing-optional (whee!) hot springs health resort. The good folks there generously let us scout the area as a potential research site.

Sulfur deposits on the hillside
The site reeks of sulfide (i.e., the sweet smell of science). Stepping into the main lodge my first thought was, "I would never get away with this in the lab". Anywhere outside a health spa, those levels of sulfide would not be considered healthy for long-term exposure, but hey, what's good for plants (in this case, low doses of sulfide) has got to be good for us, too, right?

Skepticism about the human health benefits of the spa aside, it's definitely making the microbes happy. I'm a total sucker for pigmented anythings, and there were all sorts of pretty colors here. Mostly carotenoid brown, but there were also bright pinky reds (rhodopsins? purple sulfur bacteria? what are you, pretty pink stuff?), deep blue-greens (hello, sulfide-tolerant cyanos!), and the flowing white tassels of sulfide-oxidizing streamers (maybe Aquificales?). I restrained myself at Russell's request and didn't take samples, but I did do some mat-fondling, couldn't help it.

There were also mineral structures, including little salt towers (tasted like halite, looked like mini-tufas) and crusts that were probably dominated by elemental sulfur, including some adorable little proto-stromatolites.

Sulfur proto-stromatolite
Streamers
What are you, pretty red stuff?

Russell then took me on a short hike on the surface of Venus (sweet Jeebus it was hot out) away into the neighboring nature preserve. It was like walking into a scene out of Steinbeck's East of Eden, or what I've always pictured California looking like, with the golden grass-covered hills dotted with manzanita and oak groves. Also poison oak, so we were wearing jeans, which provided no respite from the venusian oppression. However it was well worth it for the views, as well as for the fossil methane seep we came there for. The hillside was littered with chunks of fossil bivalves in the float material, as well as chunks of less macroscopically striking (but no less interesting) carbonate that were practically pleading to be isotope-d. According to Russell if you hike through the area different seep facies become apparent, but I was kind of distracted by the whole "woah! you can see the hinge on this one!" fossil thing.

Classic California Coast Range
Russell hunting for bivalves
Found some

One interesting geobiology question to ask at this site is how the specific mineralogy (and trace metal geochemistry) of the locality and spring waters influences the microbial communities present. This site sits at an old sulfur mine. Other nearby sites have springs that run through mines for other metals, gold among them. What an excellent testing ground for the Baas-Becking hypothesis ("everything is everywhere, but the environment selects")!

I'd love to get my grubby hands back in here again. Wilbur, I hope to see you again soon! (you too, Russell!)