Geologic mapping of the Cantabrian Mountains, Spain with George Evans

George is a final year geology student at Portsmouth University. You can see more of his adventures on Twitter @Geo_Evans95.

Geology and the Environment is a subject which has always captivated me from a young age, however growing up in the Midlands, Geology was hard to come by for me, so when the opportunity came to study Geology at the University of Portsmouth, UK, I could not wait to get started. 

My time at University has taken me to some breathtaking places: Scotland, Brittany, Cornwall, Cyprus, and the small town of La Pola de Gordón in northern Spain (figure 1), where I completed my dissertation mapping project.  The six week geological mapping adventure was undertaken in the summer of 2015, in the Cantabrian Mountains of northern Spain to analyse and interpret the geology to the east of La Pola de Gordón, in the northern León Province, and there was plenty of it to say the least (figure 2).

Figure 1 – Map outlining the area which La Pola de Gordón resides in.

Figure 1 – Map outlining the area which La Pola de Gordón resides in.

Figure 2 – Looking SE down on La Pola de Gordón from one of the smaller mountains in the lower half of the mapping area.

Figure 2 – Looking SE down on La Pola de Gordón from one of the smaller mountains in the lower half of the mapping area.

Myself and my mapping partner set off on this expedition from the Portsmouth Ferry Port where we travelled to Santander, meeting the one and only Nigel Marvin on the Ferry (figure 3), and from there got coaches to Leon and then La Pola de Gordón. Upon arrival our first mission was to setup our tent… probably should have packed a ground sheet! However all came good when we managed to secure an apartment a few days later which was right on the edge of our mapping area in the next town up in Santa Lucia (figure 4), so access by foot was easy!

Figure 3 – Me and my mapping partner with BBC’s one and only Nigel Marvin on the Ferry to Santander.

Figure 3 – Me and my mapping partner with BBC’s one and only Nigel Marvin on the Ferry to Santander.

Figure 4 – Selfie overlooking Santa Lucia where we were based.

Figure 4 – Selfie overlooking Santa Lucia where we were based.

Exposure mapping was completed over a provisional 12km2 area around the beautiful Spanish town, which was ripe with great pubs and eatery’s, not that these were ever sampled because we were too busy geologizing…. Either way, La Pola de Gordón rocks!

The area corresponds to passive-margin sedimentation through the Devonian, leading to foreland peripheral basins through the early stages of the Carboniferous. This is primarily in response to the initial amalgamation of Pangaea, in the form of the collision between the super-continents Laurussia and Gondwana, causing the Variscan Orogeny and the resulting Cantabrian Orocline (315-310Ma), which in turn is part of the much larger Iberian-Armorican Arc, affecting the majority of Western Europe!

The area threw up some crazy geology, and fossils for that matter, with synclinal structures almost 2km’s in width, down to cm scale trace fossils including Thallassinoides (figure 5). The rocks were 400-300 million years old spanning the majority of the Devonion and the entirety of the Carboniferous. The area is dominated by mainly sedimentary rocks such as Limestones, Sandstones and Shales which the majority have been very deformed (figure 6&7) with the Limestones more often than not possessing some lovely preservation of corals! (figure 8).

Figure 5 – Thallassinoides burrow with compass clinometer for scale.

Figure 5 – Thallassinoides burrow with compass clinometer for scale.

Figure 6 – Extensivly deformed Devonian Limestone

Figure 6 – Extensivly deformed Devonian Limestone

Figure 7 – Small scale anti-cline and syn-cline in interbedded shales and sandstones.

Figure 7 – Small scale anti-cline and syn-cline in interbedded shales and sandstones.

Figure 8 – Large colonial coral system in a bioclastic limestone.

Figure 8 – Large colonial coral system in a bioclastic limestone.

La Pola de Gordón was an exceptional place for Geology, however if you are more inclined towards travelling rather than Geology this whole area possesses some very challenging but excellent walking trails with some exceptionally rewarding results! I would suggest the Pola to Santa Lucia trail which scales the summit of the mighty Cueto San Mateo (figure 9 &10) which stands at 1604m tall – on a side note, TAKE LOTS OF WATER AND A REALLY BIG HAT, I would not be here writing this today if I did not have my enormous Indiana Jones-like hat and my camel pack, essential walking items in the blazing 38°C mountains!

Figure 9 – Panoramic vue off the top of Cueto San Mateo

Figure 9 – Panoramic vue off the top of Cueto San Mateo

Figure 10 – Looking east toward the overwhelming Limestone behemoth Cueto San Mateo

Figure 10 – Looking east toward the overwhelming Limestone behemoth Cueto San Mateo

Surrounding towns harbor equally interesting culture with lots of great bars which offer some brilliant tapas. One of the main things I miss about Spain is the tapas (figure 11), we basically survived off it for six weeks accompanied with refreshing bottles of Mahou (a great beer!).

Figure 11 – Delightful tapas at our local!

Figure 11 – Delightful tapas at our local!

Whilst the small town was in the middle of nowhere, access to nearby larger towns/cities was very good through regular buses which cost very few Euros, as we discovered when we visited León, a lovely place with exceptional architecture and many restaurants.

All in all, the experience of the whole trip from cultural differences to geology was absolutely fantastic. Having not travelled much around Europe as a child, studying Geology has allowed me to broaden my knowledge of not only the rocks beneath us, but the way the rest of the world works. My time in Spain was brilliant, the rocks, the culture, the tapas, the weather, was all amazing and I would love to revisit for a walking holiday soon!

I will finish the article with a few of my favorite images from the trip: The figure below (12) represents a vertically tilted section of bioclastic Limestone beds which are 100 meters wide and extend 500 meters to the east, and is one of the most iconic images of the area.  Figure 13 shows the entire northern section of our mapping area showing the challenging topography faced. And finally, figure 14, my favorite photo potentially ever, me, lion-kinging a plastic blue hippo off the top of Cueto San Mateo. 

Figure 12 – Iconic limestone ridge of the area.

Figure 12 – Iconic limestone ridge of the area.

Figure 13 – Beautiful vue across the northern section of the mapping area.

Figure 13 – Beautiful vue across the northern section of the mapping area.

Figure 14 – Lion-kinging a plastic blue hippo across the Cantabrian mountians – check.

Figure 14 – Lion-kinging a plastic blue hippo across the Cantabrian mountians – check.


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