Iceland: Geology
Look at the rippled texture of this rock! You can literally see how the lava was moving as it cooled and then later cracked and eroded! Looking at rocks and trying to figure out what happened in the past is like a detective game stretching hundreds, thousands, or millions of years into the past.
UPDATED: 1/22/2023
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Why Geology?
I have a little known secret that I should probably let you in on: I love rocks. Most of you are probably thinking roughly the same thing right now, “rocks…. really?” And when I say rocks, I don’t mean crystals, gemstones, or precious metals (although I like those also, who doesn’t?). I mean standard, everyday rocks.
When I discovered my fondness for these inanimate objects, I was surprised, especially because during my several Geology classes, I absolutely despised learning about rocks and saw no purpose behind remembering anything about them. I did love studying about the history of the planet and life from the distant past, but oddly enough I never made the connection between how our understanding of rocks shapes our understanding of geologic history… ah, the idiocy of youth.
It wasn’t until I began traveling that I made the connection between these two topics. Standing next to a rock face and actually being able to examine the rock layers up close connected rocks and history in a way that simply reading a book or looking at pictures could never do.
So how does all this connect to Iceland? Iceland is a country that actually owes its entire existence to relatively recent geologic events. Now you have to understand, “recent” in geologic terms really stretches the normal definition of the word “recent”. Scientists estimate that Iceland first emerged from the ocean roughly 16 to 18 million years ago as lava from volcanic eruptions cooled and formed new rock that would eventually become the island. Scientists have been studying this exact process by looking at the island of Surtsey, the southern-most island of Iceland that emerged from the ocean in 1963. Millions of years sounds like a long time but the other continents on Earth formed much earlier. In Australia, for example, scientists have found rocks that can be dated to be 4.4 BILLION years old!
Due to the young age and continued volcanic activity, almost every rock in Iceland is igneous rock. In fact, scientists estimate that over 90% of Iceland is igneous. This means the rocks you see have almost all come directly from volcanic eruptions! Everywhere you look there are signs of volcanic activity; old and new volcanoes, cooled lava flows, hot springs, and geysers are some of the amazing things you can experience in Iceland, and all are direct results of the area’s active volcanism. Iceland has such a high density of volcanoes that it is a great place to go if you are interested in experiencing the effects of volcanism.
If fire is one half of Iceland’s nature ice, is its other half. Due to the northern latitude and higher elevation of Iceland’s highlands, certain regions are perpetually capped with glacial ice. While recently the Icelandic glaciers have been in full scale retreat due to climate change, these glaciers have long impacted the geology of the island. While in Iceland, you can easily find glaciers and many can be seen while driving along the countries Ring Road.
On your trip to Iceland, be on the lookout for each of the following geological features I have explained below.
Volcanoes in Iceland
This one is obvious. Iceland is known as the Land of Fire and Ice because in addition to the many glaciers, volcanoes are everywhere in Iceland. Here you can find a map showing the major recent volcanoes and some information about each. Geologically, Iceland is unlike any other place on Earth because not only does it sit on a Hot Spot, which causes additional magma to rise and form volcanoes, but it also sits on a mid-ocean ridge where the Earth’s crust is being pulled apart and is thinner than other spots. The interaction between these geologic processes has created a country packed with volcanism.
If you plan a trip to Heimaey (read our blog here), an island off the southern coast of Iceland, you can visit Eldheimar , a volcano museum focusing on the 1973 eruption of Eldfell on the island of Heimaey and then take a hike up the "small" cinder cone volcano and walk past an entire neighborhood of buried houses located behind the museum! When we went, my hope was to take pictures from the top of the volcano, but that idea was dashed by the low clouds and rain. All I got was grey fog. When most rock on the planet is generally millions or billions of years old, there is something quite surreal about standing on rock you know did not exist only 50 years ago.
A section of the Eldfell volcano. Hiking up this makes you understand why they call them “cinder cone volcanoes”, the entire mass is made of small volcanic rubble that slips away under your feet.
There used to be an entire neighborhood here. Due to proper planning (and a bit of luck) no one died during the eruption.
If you have a desire to get up close and personal with a volcano you can find helicoptor tours or you could check out this volcano tour that actually lets you explore the drained magma chamber of a volcano! We did not take this tour (mostly because I only discovered it after coming home... whoops) but it is rated 5 star rated on Trip Advisor and looks amazing.
We also explored the Krafla Lava Fields and nearby Viti Crater located in northeast Iceland. This region erupted nine times between 1975 and 1984, and the eruptions had major implacts on the surrounding region. On the positive side much of this heat still remains underground in the region and provides access to geothermal energy. Be sure to check out the Krafla Power Plant. The folks who work at the visitor center are super friendly and will answer any questions you have while you visit. There are many hikes in this region for further exploration of volcanoes.
If you are interested in our adventures in the Krafla region check out our blog here.
The water of Viti Crater is absolutely beautiful! This area is much bigger (and muddier) than it appeared at first glance. Notice the size of the people on the far side! A nice little hike though.
Geysers, Hot Springs, and Mud Pools in Iceland
At Geysir, the southern pool of the geyser Blesi is a gorgeous blue.
Due to the incredible amount of volcanic activity in Iceland, there are large pockets of warmth beneath the surface. When water seeps into the ground, it is heated and rises back to the surface either calmly as hot springs or in the more explosive form of a geyser. One of the best places to witness this is Geysir, which gave its name to all geysers around the world, located not far from Reykjavik along the Golden Circle.
If you want to visit natural hot springs, there are many options from the Blue Lagoon near Reykjavik to Mývatn Nature Baths in the northeast. You can even soak in a thermal river! Unfortunately, my travel buddies decided they would rather spend our limited time doing things other than lounging about in the water so I can’t speak first hand about these destinations.
In some locations the water that bubbles up from below the ground is thick with fine sediment. Here you don’t experience hot water pools but bubbling mud pits. An easily accessible place to find these is the Námafjall Geothermal Area right off the Ring Road in northeastern Iceland. Beyond the obvious visual differences between water pools and mud pits the area has an entirely different feel. You constantly hear a low hissing sound as air escapes from below the ground and the rolling boil of the mud has a distinctively different sound compared to Geysir.
Rising steam at Geysir. I love the color contrast between the green moss, the white steam, and the brightly colored flowers.
Divergent Boundary in Iceland
In addition to volcanoes, Iceland sits on the Mid-Atlantic Ridge. While most of this ridge resides along the ocean floor, a small section of it can be seen running through Iceland. Along ocean ridges the Earth’s crust is actually pulling apart and new rock is created as magma below the crust rises and cools.
You can visit places such as Þingvellir National Park (read our blog here) where you can actually walk between sections of the crust, which move farther apart after every earthquake. This park is one of many places in Iceland where you can find huge sections of rifting crust. Þingvellir valley sits between two tectonic plates. As each plate moves farther apart, the valley between them sinks lower each year! It is amazing to me that one side is connected to the North American continent and the other side is connected to Europe. Each giant slab of interconnected rock is gradually separating and enlarging the Atlantic Ocean at the same time.
To be able to visit and experience this is simply amazing to me. However, even if experiencing unique geology is not high on your priority list, the area is gorgeous and packed with interesting human history and is the site of the world’s first parliament.
One of the many rifting areas at Þingvellir National Park. This area used to have a small path through it but in the past few decades there have been huge changes.
Þingvellir valley: site of the worlds first parliament and now home to the Prime minister’s summer retreat.
Columnar Jointing in Iceland
This is one of my favorite volcanic formations and is created from the pressure and stress when lava cools. Cooling lava contracts which, under the right circumstances, will create cracks in the resulting rock. Generally these cracks form five- or six-sided columns and can make truly impressive formations. If you keep an eye out you can find examples of this everywhere in Iceland. One place where we found some beautiful examples was on our journey from Hvolsvöllur to Seyðisfjörður. If you are interested read about it here.
Dverghamrar, aka dwarf rocks, is amazing for both its beauty but also the local folk lore.
Everyone else was taking photos of the beautiful black sand beaches of Reynisfjara, but I couldn’t stop admiring these amazing rocks! Seriously, I took about 50 pictures.
Glaciers in Iceland
The fog is a bit thick but beyond the mist is Vatnajökull glacier…. I think the camera is pointed in the correct direction.
If you know what to look for, evidence for Iceland’s glacial past is everywhere. The most obvious evidence for this and one that I think many would find the most exciting, are the glaciers themselves. About 11% of Iceland is covered in glaciers so if you wish to witness these first-hand you do not have to look very hard. On our trip we rented a house near the Eyjafjallajökull glacier and could see the snow capped peaks from the porch. We also visited the glacial lagoon Fjallsárlón to see the glacier Vatnajökull and the blue icebergs that calve from it. Read about that here.
If you would rather have a more up close and personal visit you can always book with tour any number of companies.
Beyond the glaciers themselves, there are other interesting geologic features to be on the lookout for. As glaciers move down the slope their massive weight will carve out huge sections of the rock below them. Many valleys people visit are shaped roughly like the letter V and are carved by rivers, but in areas of past glaciation we see unique U shaped valleys due to the shape of the glacier. A beautiful place to see this is in Seyðisfjörður.
In addition to the giant rocks left laying around, do you see the U shape of this valley? A tell-tale sign of past glaciation.
Other interesting features include glacial flutes, eskers and moraines to name a few. I have provided links explaining each. While most of you probably won’t want to take a specific trip to view these features, it is really neat to stumble upon a geologic feature and know a little bit about how it got there and what it says about the history of the region.
Skógafoss is simply breathtaking! You can see how the water is ever so slowly carving out the rock face.
The Geology Behind Waterfalls in Iceland
The twin waterfalls of Gullfoss flow over a break in the rock called a fault.
If you travel to Iceland and you do not visit at least some of the many waterfalls, you are doing yourself a disservice. Iceland has some of the greatest number and the most beautiful waterfalls I have ever seen and many have written entire articles about the “Top waterfalls in Iceland”. Due to the moist maritime climate, Iceland gets a lot of precipitation. As this water runs off the land it forms a myriad of amazing waterfalls.
From a geologic perspective, the unique size and shape of these waterfalls is often due to both the young age of Iceland and also to the geologic activity. The ground of Iceland is still actively moving, which leads to very angular geography. Erosion has not had the time to wear down the land so as water flows, it encounters steep drop-offs, which result in large and often unique waterfalls. In contrast, many other parts of the world are much much older. Wind and water have had time to erode and soften the hillsides forming large relatively flat river valleys that often lack major waterfalls.
On your adventures in Iceland and elsewhere keep an eye out for these geological features. If you are like me, then being able to identify evidence about the Earth’s past helps to further your understanding and appreciation for the places visited. Happy adventures!
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Check out our other posts about travel in Iceland:
