Þingvellir
National Park

Loaded with history, both cultural and geological. Alþingi, the Icelandic parliament, was established here in 930. An eruption occurring in the year 1000 showed contemporary understanding of the forces of natural phenomena versus enraged gods. Icelanders adopted Christianity at Alþingi after some debate between the heathen extremists and the Christians. 
In the park, the western tectonic rift edge is very clear.

View over Thingvellir rift valley
We cannot complete this trip without visiting the national park at Þingvellir. In the years of commonwealth, from 930 to 1262, the chieftains and their followers rode to Alþingi in Þingvellir to settle their debates, on Lögberg, a natural pedestal made of lava, where the law speaker used the walls of Almannagjá gore to echo his words to the congregation. From the viewing platform here at Hakið, you can easily see all the geological events we have talked about on the way, and you have seen from a distance on our hike and standing by the lake. We can see the western edge of the rift, and the valley which has formed between the two plates as they spread apart on their evenly steady pace every year. Map of Thingvellir rift valley The Þingvellir graben is surrounded by volcanoes belonging to four active volcanic systems, the Prestahnúkur and Hrafnabjörg systems in the north, and the area we were in earlier today, the Hengill and Hróðmundartindur systems in the south. Directly here north of us is Ármannsfell mountain, which was formed by a subglacial eruption which managed to break through the Weichselian glacier, forming a table mountain, strongly composed of olivine phyric basalt. As  you can see, Ármannsfell is strongly faulted. Next in line is the perfectly constructed volcano Skjaldbreiður which I mentioned to you in our last stop. Here you can easily see how huge it is, and how it  dominates the horizon to the north of the Þingvellir graben. Apart from filling the northern part of the graben here, the eruption caused a number of lava flows to enter the southern reaches of the graben and partly overflowing the somewhat older Thingvellir lava. Skjaldbreiður is the prototype of Icelandic shield volcanoes, due to its regularity. The volume of Skjaldbreiður has been calculated to be about 17 km3, and the lava covers an area of about 200 km2. One of Iceland’s naturalists and poet (1807-1845), penned a poem to Skjaldbreiður after riding around it in the July 1841. I found a translated version of it, by Dick Ringler;

Mount Skjaldbreiður (Fjallið Skjaldbreiður)

“Queen of all our country’s mountains,
crowned with snow sublime and pure!
Once you poured from fiery fountains
floods of lava down the moor.
Years have passed since rage and riot
ravaged meadow, glade, and field:
now you bear your name in quiet,
noble, broadly swelling shield!“
(Jónas Hallgrímsson)

The interglacial lava shield Lyngdalsheiði borders the Þingvellir graben. To the south it it closed off by the jagged mountains of Hengill central volcanoes and Hrómundartindur, which has produced the most basic and most evolved rocks in the Þingvellir area, like the pillow basalts of Mælifell and the andesites of Stapafell.

The opposing boundary fault is called Hrafnagjá and is 11 km long, 68 m where it is widest and has a maximum throw of 30 meters. From where we stand, you can take a walk into Almannagjá, which is 7.7 km long, 64 m where it is widest with maximum throw of 30-40 meters. This is where you can see the most dramatic structure of the giant crack when the ground was being ripped apart by the forces of the seafloor spreading.

The most recent rifting within the graben and tectonic event occurred in 1789 when the graben floor subsided 1-3 meters. The old parliament flats became unusable for venues which were then moved to Reykjavík.

I hope you enjoy the magnificent landscape and encourage you to make a short stop by the Öxará waterfall on the way. Not relevant, but if you have watched The Game of Thrones, you might recognize it as one of the filming locations in season 4.

Almannagja_trail

The bus will move to the other parking lot at the end of our walk through the gorge.

On our way back to Reykjavik, we will make a short detour for our next stop. It will be approximately 20 minutes drive.

#1 Hiking

We will take a moderate hike for the next 2.5 to 3 hours depending on your pace. We will see Nesjalaugar and Köldulaugar geothermal areas.

#2 Þingvallavatn

A short stop by the largest natural lake in Iceland which we have seen on our hike. The lake sits in the rift valley between the North- American and Eurasian plates.

#3 Þingvellir

Now we will visit Þingvellir national park, which is full of geological and cultural history. Icelanders formed their first parliament here in the 10th century.

#4 Kjósaskarð

Here we will be standing at the bottom of the valley with mountains and rivers on both sides. Imagine when the bottom used to be the top!