During our stay in Iceland, we quickly realized that the answers to just about any question you can think to ask are Glaciers, Volcanoes and Vikings.
The weather during our first day-long outing was mostly overcast and gray. We saw many lines of mountains, striped with snow in gullies, disappearing up into the clouds. We imagined great tall peaks all around us, and we hoped for better weather in succeeding days. We did get much better weather, with a few clear bright cloudless periods. We discovered that the mountains rose only a very little bit higher than the cloud ceiling. They all have flat tops. That’s when we first learned that correct answer to any question about geology in Iceland is “Glaciers.”
During the last ice age (from about 115,000 to 11,500 years ago), 2000-meter-thick glaciers covered Iceland; that’s about 1.25 miles thick! As the planet warmed and the glaciers started melting, they pushed and ground their way to the sea. They took the rocky land beneath them along for the ride. The result is great expanses of shaved-off mountains.
In many places, you can see the striations left behind from the passing scraping glaciers.
We were surprised to find almost no snow cover. Our guide said that there are a few winter sports centers, but they operate only for about a month and a half of the year. The weather is just too erratic, bouncing between below freezing with snow and wind, and above freezing with rain and wind. Lots of wind! Up on top of the flattop mountains, in the realm of the glaciers, it gets colder and windier: around -6 deg C / 21 deg F. But on the slopes and below, the conditions aren’t consistent enough to support much skiing and snowboarding and the rest.
There is abundant evidence that the flat lowlands that we find today were once at the bottom of the sea. Strata containing sea shells have been found over 100 m above sea level. ※ During the ice age, the weight of the vast glaciers kept the volcanoes and land masses pushed down. As the glaciers melted and grew lighter, the land rose up to what we experience today. Amazing to think that piles and piles of ice can be heavy enough to weigh down earth and rock.
Glacier retreat and disappearance. At one point, our guide climbed up on a pile of rocks about 500 m / 1600 ft downstream from the current leading edge of a glacier. He said that he and his wife had come to this place on their honeymoon, 31 years ago. At the time, they stood on the glacier itself higher than the top of his head today. He said that he didn’t want to get into debates about the causes of climate change, but here, and elsewhere in Iceland, he sees it all around him. Just in his adult lifetime, the glacier has retreated that much.
These glaciers are beautiful and awe-inspiring to behold. And sad and depressing too.
It’s all about plate tectonics. Iceland sits atop the rift where the North American and Eurasian tectonic plates meet. The two plates move away from each other at a rate of about 2 cm / 1 in per year. This is why there are so many volcanoes in Iceland. There are over 130 volcanoes, of which about 30 are active. The mid-Atlantic island groups of Madeira, Azores, Canaries, Capo Verde are all part of the same tectonic dynamic.
We visited a site where we could see the edge of the North American plate. Imagine the tectonic plate that extends from the middle of the Atlantic Ocean all the way to the west coast of North America and even into far-eastern Russia. You’re staring at the ripped edge of this plate.
Right here, along the exposed edge of the North American plate, early Icelanders established their innovative parliament in the year 930. Þingvellir or Thingvellir was the site of the Alþing or Althing, the annual parliament of Iceland, which convened here until the last session in 1798 when the Danes took over. The Althing is one of the oldest national parliaments in the world. Things were representative assemblies of freemen (thing is the root word of Althing); they were widespread throughout medieval Scandinavia. This Althing, however, was the first such body to exercise legislative power at the national level. ※ Many Icelanders view the establishment of the Althing in 930 as the founding of the nation of Iceland.
There are quite a few stunning black-sand beaches in Iceland. The sand is black because not that long ago the sand was black volcanic rock.
At Reynisfjara Beach and along the south coast of the Snaefellsnes peninsula, we saw these handsome cliffs of basalt columns.
More evidence of volcanic hyperactivity:
Iceland basalt columns: How they are formed
Basalt is a volcanic rock formed from the superheated magma that emerges as lava during an eruption. The iron and magnesium-rich basalt lava cools and contracts very quickly once exposed to the surface air and hardens as it solidifies.
Iceland basalt columns are the result of this rapid cooling process that changes the chemical makeup and appearance of the lava. Basalt volcanic rock has a special geometrical shape due to this change in composition.
These basalt pillars and hexagonal rock formations you see have a special feature called columnar jointing. This is what gives each basalt column their unmistakable hexagonal shape and makes them so neat to look at. (source)
Black sand beach and sneaky swells. At Reynisfjara Beach, our guide took a very serious tone. He said that heading directly south from here, the next land you’d reach is Antarctica. There’s a planet’s worth of wild ocean bearing down on this beach. He warned us about the unpredictability of so-called sneaky waves. You just never know when a random large wave will crash on the beach, reach far inland, and take you away. Apparently, a few tourists get swept out to sea each year. (This reminded us of the sad reality of regular ocean drownings around Hawaii because people don’t understand and respect the power of the ocean.) We kept an eye on the surf at all times for sure!
When masses of black lava meet the perpetual grinding of the North Atlantic, we get beautiful awe-some coastline.
We visited Strokkur geyser, one of the most famous geysers in Iceland. This place was yet more evidence of heat and magma roiling beneath our feet. (Nerdy language fact: the English word geyser comes from the Icelandic word geysir, which means to gush.)
Strokkur is found in the Geysir Geothermal Area, titled after the Great Geysir, which lent its name to all others across the world. It is the greatest active geyser on site; Geysir itself is in a period of inactivity. Strokkur erupts more regularly than Geysir ever did, blasting water to heights of around fifteen to twenty metres every five to ten minutes, although it is known to reach up to forty metres.
Active geysers like Strokkur are rare around the world, due to the fact that many conditions must be met for them to form. They are thus only found in certain parts of highly geothermal areas.
The first condition that is necessary is an intense heat source; magma must be close enough to the surface of the earth for the rocks to be hot enough to boil water. Considering that Iceland is located on top of the rift valley between the North American and Eurasian tectonic plates, this condition is met throughout most of the country.
Secondly, you will need a source of flowing underground water. In the case of Strokkur, this comes from the second largest glacier in the country, Langjökull. Meltwater from the glacier sinks into the surrounding porous lava rock, and travels underground in all directions.
Evidence of this flowing water can be found in Þingvellir National Park, where there are many freshwater springs flowing straight from the earth.
Finally, you need a complex plumbing system that allows a geyser to erupt, rather than just steam from the ground like a fumarole. Above the intense heat source, there must be space for the flowing water to gather like a reservoir. From this basin, there must be a vent to the surface. This vent must be lined with silica so that the boiling, rising water cannot escape before the eruption. (source)
Að framhald verði á… To be continued…