Geology in Iceland

Following on my previous post on Iceland’s building stone, I want to look a little at the country’s landscape. As I wrote previously, every geologist should go to Iceland. We spent about ten days there, traveling along the southern coast and then north of Reykjavik (Reyk meaning smoky or steamy and vik meaning bay) out the Snæfellnes Peninsula (a bit of a redundancy as nes is Icelandic for peninsula). We were also lucky enough to be in Iceland when a volcano erupted; we were just 20 miles or so from Grimsvötn on Friday, the day before the eruption.

In one sense, Iceland is geologically simple. Nearly every rock you see is basalt. You may find a few fossils and a few sediments but you would have to seek them out. This is a place that, as trite as it sounds, is a land of fire and ice. Driving along the south coast, you travel along plains of basalt flows, or glacial outwash. Some are still black and devoid of much vegetation but in many areas, carpets of lush mosses grow thickly atop the flows. A few shrubs sprout but no trees grow, even along streams.

As you look inland, the landscape begins to climb, as scree slopes and more commonly as basalt cliffs, layer upon layer rising straight up. Waterfalls regularly cascade over the cliffs, a product of the gargantuan ice sheets that cover vast swaths of the interior. At Skaftafell National Park (part of Vatnajökull NP), we hiked up the shoulder of Skaftafellshei∂l (fells means mountain(s) and shei∂l equals shield) just west of the Skaftafelljökull icefield (again redundant as jökull means glacier). We did encounter some trees up here, birches and willows, but they were low growing, about as tall as me. In the desert southwest, we call such a woodland a pygmy forest, which I am not sure is PC or not.

Of all the wonderfull geology, two spots stood out. The first was the vast glacial outwash plain or Skei∂arársandur, which stretches for 500 square miles of soil, silt, pebble, gravel, and boulder with little to no vegetation. A two lane road snakes on a berm across the sandur with two, 1/2–mile-long, single lane bridges spanning areas of braided streams.

The day we drove the road the wind blew. A sign we saw showed that wind gusts peaked at 41m/s or about 90mph. (We read one sign that stated “a light breeze is just hurrying by.”) As you might suspect in a landscape lacking vegetation and comprised of rocky bits, the wind became visible as streams of sediment ripping across the road (thank goodness for rental cars!). At times we could barely see in front of us. Fortunately, we didn’t pass any cars at all crossing this stretch of road. At least we didn’t see any other cars.

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When we finally emerged out of the wind, we stopped at a road side table. Signs informed us that in 1996, an eruption of Grimsvotn led to a truly stupendous jokulhlaup (glacial flood) bursting out of the Skei∂arárjökull. The estimated flow was 53,000 m3/s or 1.87 million cubic feet per second. Only one river on earth has an average flow greater than this flood. The Amazon runs at about 180,000 m3/s.

My other favorite spot was Hraunfossar (lava falls), a series of turquoise water falls that emerge as springs on a low ledge above the Hvita (white river). The springs run for about a kilometer with water cascading from the moss-covered basalt down to the river. It was quite stunning.

These are just a few of my impressions of Iceland. I hope to write a bit more in the future.



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