Bethany Ehlmann is touring with students in Iceland to learn more about the dynamic geological processes that mold and carve our planet in order to gain insight on other planets, particularly Mars. The research that she and her students conduct can tell us more about how other planets work, how they might host life, and how we might one day colonize them.
Welcome to Iceland! I’m spending the next 12 days with 15 students, two fellow faculty, one intrepid driver and a river-forging 4WD bus, circumnavigating the island. Iceland is special: in an area only about the size of Kentucky, it’s got some of the rawest geology on the planet. Raw, because every bit of land on the island is younger than 15-million years old—the blink of an eye in geologic terms. Volcanoes spewing ash and lava are still building Iceland from the sea floor. Glacial ice and waters then carve away at the rock while all the heat from below pumps steaming hydrothermal waters to the surface.
We’re here to teach geology. In the field. Where you can touch the rocks, see the relationships and smell the silty streams from glaciers or the rotten-egg sulfur smell of hot springs. I’ll keep you posted as we go, hitting the highlights and talking also about why Iceland can teach us so many lessons about my other favorite planet, Mars.
Jet-lagged and bleary from a 15-hour journey, we rolled off the plane to an Icelandic sunrise over the volcanic plains near the capital, Reykjavik. Straight onward to geology, we eased in via the Golden Circle, an amazing (and convenient) set of nearby stops—take it if you find yourself an Icelandic tourist!
We began at Pingvellir, site of Iceland’s first parliament. But it’s also near and dear to geologists because the green valley holding the beautiful river is a rift zone between the North American and Atlantic tectonic plates. Iceland is right on top of the pull-apart zone. The Pingvellir valley is a downdrop graben that sinks as the crusts pull further apart, exposing spectacular steep cliffs of basaltic rock. Basalt is an iron- and magnesium-rich and silica-poor volcanic rock that forms over 90 percent of the island. This is also the stuff of which Mars is made.
Having crossed off the list one of Iceland’s big four—basalt, more on it later—we turned our attention to number two and three: waterfalls and hot springs! We kicked our first of many waterfalls off to a good start with a visit to Gullfoss, where the cascade pours through two levels of falls, making a sharp 90-degree turn where the river encounters a fracture in the basaltic lava flows (probably a smaller version of the graben at Pingvellir). Like some Mars channels, the sheer walls of the restricted channel are carved in rock. Huge cascades of water from melting ice and snow carve a new landscape into stark, dramatic falls. Dry now, could Mars’ channels have hosted drama like that at Gullfoss?Fumaroles (steam vents) at Landmannalaugar spew forth water vapor tinged with hydrogen sulfide, producing a classic rotten-egg smell but leaving colorful deposits of sulfur, silica, and other mineral phases behind. (Photo by Bethany Ehlmann)
Then to nearby Geysir. Yes, this is what geologists call type locality where the process on display is so archetypal, the name sticks. Geysir shoots off an approximately 40-foot plume in regular intervals, but, gotta admit, I was drawn to the quieter hot spring holes nearby. Groundwaters at boiling point temperatures pool and slowly overflow, leaving behind apron-shaped deposits of silica. This whitish, hard patina shields the rocks beneath from erosion as well as creates a nice color contrast with the light blue waters. We see deposits that might be similar on the flanks of the Syrtis Major volcano on Mars (Skok et al., 2010, Nature Geoscience). Silica deposits orient downslope in either case.
At Geysir in Iceland, orange and pink microbial mats, adapted to live in high temperatures, attach to the channels leading from the pools in a spectacular rainbow of color. It’s why folks looking for life on Mars get so excited for certain minerals. We also made a stop at Landmannalaugar, site of mountains of rhylotic lava (more silica-rich than basalt) and ash from explosive volcanic eruptions. The heat can still be seen, not in geysers, but in fumarolic vents that steam sulfurous waters. The resultant alteration of lavas and ashes to a rainbow of minerals creates colorful hills.
Now it’s off the the highlands! We’re crossing north to south through the desolate, windswept volcanic plains. A broken rock and pebble field stretches as far as the eye can see until interrupted by one of Iceland’s icefields.