Road Trip to the Glacial Lagoon!
Today’s journey started at 08:30 am. The air was cool and the sky was mostly clear as we headed east for today’s primary attraction: the Ice Lagoon at Jokulsarlon Glacier. This was to be a 7-8-hour round-trip drive with commentary on the passing geologic phenomena, and occasional stops along the way.
Almost as soon as we left the cabins, we were presented with a somewhat clear view of the Westman Islands to the south. The view was only partially obscured by a dusty haze that had blown off the mainland overnight. These islands (numbering around 40) are a part of the Southern Icelandic Volcanic Zone on Iceland and are the southernmost point in the country. There are roughly 4000 people living on the main island of Heimaey, and the area is mostly known for an eruption in 1973 that forced a significant portion of the population to evacuate.
Soon after sighting the islands, the glacier Eyjafjallajökull became visible to our north (Photo 2). This is the site of the 2010 eruption that caused major disruptions to travel in the later half of that year. (It is interesting to note that the name Eyjafjallajökull refers only to the glacier; the volcano that erupted underneath has yet to be named.
Ólafur Jón mentioned that all of the glaciers may not last much longer than 200 years due to climate change. Other indicators of climate change include changes to the migratory habits of some birds, which are either leaving later and returning sooner, or not leaving at all anymore as the southern Icelandic climate becomes increasingly milder. We then entered the Katla Geopark area, which comprises of 80 km2 of managed land use. The goal of the Geopark is to provide and maintain a balance between nature, commerce and industry.
We then passed along the southern flank of Katla, which is considered the most dangerous volcano in Iceland due to its long history of violent eruptions. Katla is also covered by a thick ice cap, which further increases the danger in the event of an eruption due to the explosive interaction between meltwater and liquified rock. Katla has erupted five times in recorded history, with events occurring in 1721, 1755, 1823, 1860 and 1918.
At around 09:40 am, we were greeted with a view of marine terraces on the flanks of the volcano.
These terraces represent position of paleo-shorelines uplifted above current sea level and indicate thousands of years of relative sea levels fall due to land uplift. (Uplift is due to isostatic rebound caused by glacial retreat during the Pleistocene and at the beginning of the Holocene.) We then passed the southernmost town in Iceland (Vik) as well as several prominent sea caves left exposed on the hills (also due to sea level change caused by isostatic rebound). Also in view were several large landforms rising from the coastal plain. These landforms originally started out as islands, but sediment outflow from glacial meltwater-fed streams and rivers have since completely filled in the areas between the former islands and the headland.
Just past 10:00 am we were able to glimpse Iceland’s highest peak in the distance. Hvannadalshnúkur stands at approximately 2.2 km above sea level, but this actually changes seasonally depending on the snowpack thickness. This point (and the ice surrounding) comprises Iceland’s largest glacier, Vatnajökull, which covers ~8% of Iceland’s total land area. Hvannadalshnúkur is actually a peak on the rim of Iceland’s largest active volcano, Öræfajökull, the site of a major eruption in 1362 AD. Öræfajökull is one of only three stratovolcanoes in Iceland, which results in eruptions consisting of pyroclastic flows, explosive eruptions and lava flows.
Presently, we found ourselves being driven through a basalt-covered volcanic landscape similar in appearance to the flood basalts that cover a significant portion of the Reykjanes peninsula to the east. The major difference in appearance is due to the frequent glacial meltwater floods that sweep over this area. These floods carry sediments that have slowly filled in the cracks and fissures that are a prominent feature of the Reykjanes basalts. This results in a flat area (coastal plain) interspersed with mounds of jagged lava. These flood basalts are a product of the 1783 AD eruption of Laki, during which a 75 km long series of fissures erupted lava non-stop for 8 months (23 consecutive days of which were explosive). This eruption also produced significant flooding and added ~14 km2 of new land to Iceland (which has since succumbed to wave action and long-shore current). It is no wonder then that many of the farms seen throughout the region are found high up on the hills above the coastal plain.
That 1783 eruption of Laki also released a huge volume of toxic gases (estimated at 200 Mt of sulfur aerosols and 94 Mt of other toxic gases) which caused a marked decrease in global temperatures over the next several years. This led to crop failures and famine in both Iceland and Europe.
At around 11:00 am, we passed by a local landmark known as the Giant of Lómagnúpur, which is represented as part of Iceland’s coat of arms. The Giant is a mountain on the northern end of a vast area of glacial outwash. This area contains excellent examples of glacial geomorphology, including a rock glacier to the north (where a layer of rock covers the icy core of the glacier), longitudinal and recessional moraines and ripple marks in the outwash plain. We stopped for lunch at 12:00 near the bottom of a tongue of Vatnajökull in an area of large longitudinal moraines covered in moss and low brush.
We finally arrived at Ice Lagoon shortly after 13:00. The lagoon is an area at the base of Jokulsarlon Glacier surrounded by terminal moraines. The water melting from the glacier has formed a lagoon in which icebergs have calved from the face of the glacier.
The lagoon has an ocean inlet, and water flows into and out of the lagoon with the tides. When the icebergs become small enough, they can pass through the inlet in to the north Atlantic, then they either float out to the open ocean or become caught in the longshore current where they eventually become beached at the shore (if they haven’t completely melted yet). Ice lagoon is stunning, with deep, azure water interspersed with floating chunks of ice ranging from pure white to dark grey, with stripes and shapes of every size. We were fortunate to be visiting on a warm, sunny day, and it was a treat to witness such a spectacle in such hospitable weather.
After a two-hour stay at the lagoon (which included a trip by the author to the adjacent beach to witness icebergs exiting the inlet on the outgoing tide), we started back to our temporary accommodations at the cabins. On our way back we made three more stops: the first in an area of large recessional moraines (in which to observe a similar glacial-lagoon environment).
The second stop was an excavation in which multiple layers of ash deposits could be seen in the exposed face of a soil column.
And the last stop was to visit the site of a bridge that had been damaged by the recent glacial flooding. Here was visible layers of columnar basalt and tephra, and the damage included the caving in of the sides of the river, and undermining of the bridge supports.
Our day concluded with a pizza dinner back at the cabins just after 20:30.