An ancient ocean floor in the Alps?

After the adventures in Italy and Switzerland it was time to start the fieldwork part of my trip in Briancon. Part of this involved a visit to the Chenaillet Ophiolite in the French/Italian Alps.

Looking north with the large pillow lavas outcrop in the foreground
Looking north from the Chenaillet Ophiolite

Some Basics

To think about what an ophiolite is we first need to go back to some basic geology…

The outer layer of the Earth is made up of numerous large pieces which can move relative to one another in a theory known as plate tectonics, we use this to explain many of the phenomenon that we observe on the Earth. There are two types of crust making up the outer layer of the Earth; so called oceanic and continental crust. Oceanic crust is thinner, yet denser than continental crust.

This animation gives some idea of how a mid-ocean ridge may look and function but I'm not entirely convinced. http://upload.wikimedia.org/wikipedia/commons/c/c0/Mid-ocean_ridge_topography.gif
This animation gives some idea of how a mid-ocean ridge may look and function but I’m not entirely convinced…
http://upload.wikimedia.org/wikipedia/commons/c/c0/Mid-ocean_ridge_topography.gif

Oceanic crust is created at Mid ocean ridges. These are essentially underwater volcanic mountain chains where the erupted material produces new crust. They mark the boundary between different plates, and are referred to as a divergent boundary as the plates are moving away from one another.

http://en.wikipedia.org/wiki/File:Earth_seafloor_crust_age_1996.gif
Ages of the ocean floor. Oceanic crust is created at the Mid-ocean ridges and destroyed at subduction zones, because of this the crust closest to the mid-ocean ridges is youngest and the oldest is found closest to the edges of the Oceans. http://en.wikipedia.org/wiki/File:Earth_seafloor_crust_age_1996.gif

The difference in density between different crustal units is crucial to allow a process called subduction to take place. Subduction occurs when two plates move towards each other and the denser of the two goes underneath the less dense plate. Subduction zones are the opposite of mid-ocean ridges in that they are a convergent boundary, meaning that the plates move towards one another. As a result of subduction oceanic crust is essentially destroyed, as it is sent back down into the Earth.

Looking out over the Chenaillet Ophiolite in the Franch–Italian Alps. The blue areas of scree represent weathered outcrops of the serpentinised peridotite.
Looking out over the Chenaillet Ophiolite in the Franch–Italian Alps. The blue areas of scree represent weathered outcrops of the serpentinised peridotite.

When we observe rocks which have the characteristics of the oceanic crust on top of continental crust we call these abnormalities ‘ophiolites‘. The word Ophiolite apparently literally translates to ‘snake rock‘ referring to the similar aesthetics of the rocks found in ophiolites and snake skin. Ophiolites have taught us a lot about oceanic crust and tectonics but there is a catch; if normal oceanic crust is subducted back into the Earth then for ophiolites to have been preserved must mean that they do not represent “standard” oceanic crust.

So oceanic crust is created at mid ocean ridges and destroyed at subduction zones, but how did we end up with a segment of oceanic crust high up in the French Alps? Why was this segment of oceanic crust not subducted?

How do we know that the rocks here in the Alps are in fact oceanic crust?

Firstly, we have got abundant outcrops of Peridotite. Peridotite is a ultramafic igneous rock (contains less than 45% silica and solidified from melted rock). Peridotite is the main rock type in the upper mantle and it wouldn’t just form here, it needs to have been produced elsewhere and put here.

A small fragment of the serpentinised peridotite
A small fragment of the serpentinised peridotite

Another major piece of evidence is that the peridotite has undergone a process known as serpentinisation. This is a chemical reaction which occurs through contact with sea water, and has produced many of the minerals in the fragment shown above.

Angular fragments of serpentinised peridotite incorporated into a carbonate
Angular fragments of serpentinised peridotite incorporated into a carbonate rock

The photo above shows that some of the peridotite has been reworked and incorporated into sedimentary rocks (rocks made up of fragments of older rocks). The darker parts are the peridotite and the lighter surrounding material is limestone. Limestone of this type is produced under the sea which is further evidence towards the oceanic origin of these rocks.

Pillow lavas
A spectacular outcrop of Pillow lavas

Finally at the Chenaillet Ophiolite we observe large outcrops of pillow lavas. Pilow lavas are volcanic rocks which were produced underwater, providing further evidence towards the oceanic nature of these rocks.

How did these rocks get here?

These observations of rocks which seem out of place confused early geologists, and it wasn’t until the theory of plate tectonics was established that these suits of rocks were understood to represent small fragments of the oceans attached to the continents.

The process of ophiolite emplacement is termed obduction, and is defined as the overthrusting of oceanic material on top of continental.  Obduction occurs at convergent tectonic boundaries (i.e. where two plates are moving towards one another), this explains why we often find ophiolites incorporated into the mountain chains produced at these boundaries.

Numerous mechanisms have been proposed to explain why obduction occurs rather than the expected subduction but they often struggle to be applied to all cases. It is therefore generally regarded that there is no singular mechanism responsible for all ophiolite occurances, and that more work is required to understand the formation of ophiolites…

The Bernina Alps

Following on from the climbing down in Italy we decided to head back to Switzerland and see if the weather would give us a break. James and Harry had intended to do The Cassin Route on Piz Badile but a quick drive along the valley confirmed that this classic rock climb was covered in snow. This set us about weighing up our options.

The Original plan: Piz Bernina
Piz Bernina

I had no particular objective so was happy with just getting up high, and do something productive. So the three of us set off to climb in the Bernina Range.

Day 1
The walk up to the Diavolezza Hut wasn’t particularly long or hard, just pretty boring following a large track for several hours. I presume the track was there from building the cablecar and hotel at the top. Getting the cablecar would have made life a lot easier, but none of us could bring ourselves to pay that many francs when it can be walked in only a few hours. However I’ve subsequently learned that in order to give yourself the best possible chance on any given route in the Alps it is paramount to reach the bottom of it in top condition!

From the Diavolezza Hut looking towards Piz Palu (lefthand  peaks) and the Bellavista range (righthand Peaks)
From the Diavolezza Hut looking towards Piz Palu (lefthand peaks) and the Bellavista range (righthand Peaks)

At Diavolezza we met some Germans with a guide planning to climb Piz Palu.
When we told them we were planning to stay in the winter refuge at Marco e Rosa Hut one exclaimed “peugh! It is little more than a container!” We thought that the winter refuge at Marco e Rosa Hut was fantastic. Not sure how they would have reacted if we had told them we were planning to sleep outside the hotel to save money!

Making food
Making food

The Diavolezza Hut gave us a good vantage point to plan the next day but most of what we encountered could not really worked out until we were on it the next day.

Weighing up the mountain from the Diavolezza Hut
Weighing up the mountain from the Diavolezza Hut

Day 2
This was a long day by any definition. A 4am start with a complex glacier crossing started the day off, followed by an extremely long steep snow plod with a section of mixed climbing.

A minor detour from the intended route actually took us to the highest point we would achieve Bellavista (3922m). This less frequented summit was actually quite interesting with a narrow ridge leading away from it which we decided wasn’t safe to use, meaning we had to descend the way we came up.

From the summit of Bellavista looking towards Piz Palu
From the summit of Bellavista looking towards Piz Palu

After coming back down from the Bellavista we started heading towards the Marco e Rosa Hut, which involved more slow upwards progression on snow slopes and glaciated terrain. with time ticking by a summit attempt on the Piz Bernina was now looking less than likely today. Just getting to the hut would be enough for today.

One of the “interesting” sights of this part of the day was the group of climbers having lunch under the shadow of a melting serac in the afternoon sun…

Marco e Rosa Hut
Marco e Rosa Hut. Preety amazing place to put a hut. I think the hut is located just inside Italy.

The journey from the Diavolezza Hut to Marco e Rosa Hut took about 9hours, by which time exhaustion and altitude were taking there toll. It was also too late to have a reasonable go at summiting the Piz Bernina, so we decided to attempt it the next day if conditions allowed.

View from The Marco e Rosa Hut
Evening view from The Marco e Rosa Hut

When I arrived at the Marco e Rosa Hut I was totally shot. The combination of exhaustion and altitude had really got to me. Taking my sleeping bag out of it stuff sack felt like too much, I had to just get inside with the kit I’d been wearing all day, try not to hyperventilate and sleep it off. Ive never felt that bad ever, it was like the worst hangover ever mixed with being really cold and not being able to breath properly. I managed to sleep it off for a few hours, ate some cheese and then seemed to feel ok again. If I’ve learned anything from this trip it is the importance of being properly acclimatised, going from near sea level to nearly 4000m in two days doesn’t work too well!

Feeling a bit better having got over the worst of the altitude/exhaustion at Marco e Rosa Hut
Feeling a bit better having got over the worst of the altitude/exhaustion at Marco e Rosa Hut
Sunset from The Marco e Rosa Hut
Sunset from The Marco e Rosa Hut

Day 3
Having not managed our initial objective the day before we had hoped to get an early start, but the conditions were doing all they could to put an end to this.

The sequence of events went something time this:

3:45am: too much wind.

4:00am: Harry volunteered to go outside to check wind situation. Still windy. Back to bed.

5:00am: Continuation of strong wind theme. Running out of time to do Piz Bernina.

8:00am: Pushing the limits of what can be considered an “Alpine start” but there was no point in getting up early if we weren’t doing the mountain.

Working our way back
Working our way back

After the “late” start we started making our way back. The first technical challenge of the day was to safely cross the glaciated terrain near the hut. This went pretty smoothly and we made good progress to the multiple abseils down the mixed section.

Descending towards the glacier
Descending towards the glacier…
Descending towards the glacier
More descending towards the glacier…

After the multiple abseils the only technical challenges left were descending the exposed slopes to the glacier and crossing the glacier. This decent wasn’t technically hard just typical Alpine “don’t fall off” terrain.

Looking over the glacier to the Bellavista
Looking over the glacier to the Bellavista

Glacier crossing is less stressful in the daytime because you can see more of what is underfoot, but I found it a bit frustrating when you can see the place you are trying to get to but cannot just strait line it because of the crevasse systems.

Even when you think you are off the glacier on the moraine at the side the glacier extends underneath you as this ice poking through shows from a few meters away from where the main glacier ends.
Even when you think you are off the glacier on the moraine at the side the glacier extends underneath you as this ice poking through shows from a few meters away from where the main glacier ends.
The Bellavista from Diavolezza Hut
The Bellavista from The Diavolezza Hut

Overall it was a good adventure but I am slightly disappointed to have not completed the planned goal of the Piz Bernina. The mountain will however always be there, and not always succeeding is just the nature of this game. I guess it just puts those times it does work out into context.

Made it down!
Back at the van

Geneva to Zurich to Lecco

Firstly apologies for the length of time it has taken me to post since coming back. This is the first of a few posts I’m planning to do about my trip.

After a night in Geneva I got the train to Zurich where the plan was to meet some friends who had driven down from back home. The plan was then to head down to near the Swiss-Italian border to climb but the weather was doing its best to stop us! It rained all the way from Geneva to Zurich, then pretty much all the way through the Alps as we headed south. It was only pretty much as we crossed the border into Italy that the rain stopped.

View from the van
Morning view from the van

Our first day got off to a pretty slow start due to lots of travel in the previous days and the absence of a guidebook to the area. Having eventually located a bookshop, and thus a guidebook we began attempting to locate the crag from the mediocre description in the book. After becoming well acquainted with most of the minor roads/dead ends in the area we found Galbiate.

James climbing at Galbiate
James climbing at Galbiate

Galbiate is a small crag in the trees above the town of the same name. It reminded me of  Giggleswick (in setting not quality or climate).

James climbing at Galbiate
James climbing at Galbiate

On our second day in the area we decided to do something bigger, and opted for a multipitch called Condorpass on Zucco dell’Angleone. This was a great route about 10ish pitches long, with fantastic view over the area.

View from Condorpass
View from Condorpass on Zucco dell’Angleone
Harry and James on a belay on Condorpass at Zucco dell'Angleone
Harry and James on a belay on Condorpass at Zucco dell’Angleone
Harry on Condorpass
Harry on Condorpass
James on Condorpass
James on Condorpass

Northern Italy provided us with everything we needed; good weather, cheaper than Switzerland and close proximity to the main objectives in the Alps. I would definitely recommend this area of Italy, but not just for escaping the weather in the Alps but also as a top quality area in its own right.

Alpine bound

When I was first offered the opportunity to head out to Briançon in the French Alps for fieldwork in September I immediately jumped at the idea. I love fieldwork, especially in places like the Alps! It got even better when I found out that I could add a climbing trip on as it made no difference to the university if I flew out a week early, then returned a few days late.

Well organised kit whilst packing tonight
Well organised kit whilst packing tonight

So anyway I doubt I’ll be posting too regularly whilst I’m out and about but I can promise a combination of interesting climbing and geology posts from this trip on my return:)