Volcanoes on a Shoestring at 20!

In 1996, soon after organising a successful trip to the Pyrenees, led by Bill Gaskarth (who was a OU tutor and based at Birmingham University in those days), Jan Ashton-Jones and I were thinking how nice it would be to take OUGS groups to places like Iceland and Hawaii but bemoaning the cost of such trips which was way beyond what we personally wanted to spend.

A tectonic window in the Spanish Pyrenees was a chance for Bill to show us the metamorphic basement at the head of the La Larri valley - 1996

Around the same time, Robin Gill from Royal Holloway College wrote a GA Guide to Tenerife: we looked at this guide, and at the possibility of cheap flights, reasonably priced accommodation, and inexpensive meals and car hire, and Volcanoes on a Shoestring was born! Our first trip was to Tenerife in 1997 and based on his guide: technically a DIY trip but in fact it needed a good deal of preparation to fill out the information in the GA Guide and Louise Thomas at the OU, who had recently completed her PhD based partly around fieldwork on the island, was very helpful. So helpful in fact that we invited her to lead the 1999 trip! But I’m jumping ahead.

On some of the earliest Tenerife trips we were able to visit the spectacular Barranco del Infierno - this is now so popular that it is ticketed, timed entry.

For that first trip to Tenerife we found inexpensive self-catering apartments in Callao Salvaje and it was helpful to have OUGS people along who knew the island and, indeed, the resort.  Maíre O’Brien and her husband Barry were particularly helpful, especially when one of the group managed to walk through a plate glass patio door one evening and needed to be taken to A&E!  Despite that, early in 1998 Jan “had a silly idea – shall we do it again?” So we did! And in 1999, 2002, 2004, 2006, 2008, 2009, 2011 and 2014. In between times we managed to combine the 1999 trip with a week in Lanzarote before branching out into other volcanic islands, Sau Miguel (Azores)in 1996, and then Fuerteventura (with excursions to nearby Lanzarote) in 2010, 2012, 2013 and 2017.

In 1999 Jan and a few others climbed Montana Blanca on the mid trip "free day"

At various times we’ve also based the Tenerife trip in Vilaflor, Buzanada and La Escalona – all well placed for exploring both the caldera and the wonderful ignimbrites of the Bandas del Sur. Lanzarote accommodation has been in Costa Teguise and Puerto del Carmen whilst on Fuerteventura we’ve found self-catering bungalows and apartments in Caleta de Fuste midway down the island. Although the first trip to Lanzarote was a follow on from Tenerife it isn't a natural pairing as it means an internal flight, involving a length change between the north and south airports on Tenerife. The two-island trip works much better with Fuerteventura where Lanzarote is a 20 minute ferry ride from Corralejo, using the same hire cars on both islands. We were amused to meet another group on Fuerteventura one year who had come over for the day from Lanzarote... the next year we noticed they were staying on the F-island for a week with a day on the L-island!

A highlight of the Lanzarote trip in 1999 was the guided walk through otherwise inaccessible parts of Timanfaya Parque Nacional

For me, that first Tenerife trip was a total eye-opener! I’d never seen volcanic rocks apart from one or two elderly pillow lavas, Silurian lahars in the Mendips etc. but never anything so new. The first year we did it completely cold – the GA guide, and Louise, told us what to look for and we took it from there, learning "on the job". There is such an amazing variety of ocean island volcanics on Tenerife that it is a great place to get to see as many different types as possible! Since that first trip there have been another nine Tenerife trips alone and it has been great fun finding new localities to visit and seeing how the research on the island's geology, and especially the hazards aspect of volcanic islands, has progressed over time.

On many Tenerife trips we've enjoyed walking round the Roques de Garcia, though the climb back up to the road at Los Azulejos (here) is quite a challenge at 2300 m!

As well as volcanoes, the Shoestringers spread their wings wider – a series of “Suture on a Shoestring” trips explored the Iapetus Suture from east to west in Arctic Norway and Sweden (2011), Southern Norway in 2002 (both with Mark Anderson from Plymouth), then nearer to home, a “Not SXR339” week at Kindrogan in 2007 with multiple local leaders. On the first Norway trip some of us were able to take the ferry to Bergen, sadly no longer possible, but on the second we flew into Narvik before driving first east to Kiruna mine (the huge iron mine - where the town is being moved so that mining can continue) and then west to the Lofoten islands. 

Norway 2002 - the eclogite exposure at Flatraket

Mark was amazing on the first trip - his research area was northern Norway so he was doing the south completely "cold" with just hints and tips from colleagues and had to make use of the long summer evenings to go out and reccy the following day's stops. On the second trip we started off in Abisko which he knew well and he was able to visit his research students who were scattered across the landscape!

On the foreshore near Narvik - Norway 2011

In 2006 Bill Fitches took us “In Search of the Suture” on the Isle of Man and then in 2008 we crossed the Atlantic to Newfoundland with Tom Sharp who knows the island so well. We experienced an amazing fortnight there, neatly timed to be just in time to see the last of the season's icebergs drift past. 

In search of the suture at Langness on the Isle of Man in 2006

Newfoundland's Mistaken Point where we saw stunning Ediacaran fossils with Tom Sharp in 2008

In the final "suture" trip in 2012 we wound up a little further west on Canada’s Gaspé peninsula with Brian Williams and Ken Higgs. The perennial aim of keeping trip costs down was challenging at times, especially in places like Canada and Norway but Jan rose to it well!

Brian Williams took us to see the wonderful Devonian fish at Miguasha on Gaspe's south shore in 2012

Extending the “Shoestring” ethos to mountain chains, we visited the Alps with Bill Fitches in 2000 – an amazing fortnight with an initial few days exploring the Helvetic Nappes west of Martigny and the ophiolite in the Taschtal before two complete transects of the Swiss Alps - over the Simplon Pass to Locarno and then back via the Lucomagno pass and back down the Rhone valley. Jan and I had driven over in her campervan beforehand and met some of the group at Geneva airport, whilst others drove or came by train, some camped and some stayed in hotels - quite a logistical challenge!

Pausing for a breather on the climb up to the Lac de Salanfe in the Alps in 2000. So good we did it twice!

Mark Anderson on pseudotachylite in central Spain

Following on the "sierras" theme, Mark Anderson led a four day “Sierras on a Shoestring” trip to the Sierra de Guadarrama north-west of Madrid and the “volcano” trips in Almeria in 1998 (Bill Gasgarth), 2000, 2005 and 2010 (me) also included the “sierras” element  of the Betic basement besides the Cabo de Gata volcanics. 

Exploring caves in gypsum karst in Almeria

As well as the "shoestring" trips, Jan also managed to organise trips to the UAE (nothing alliterative there .... camels on a shoestring perhaps? ;) ... and anyway it wasn't quite as "shoestring" as some, though we did get a good bargain for a group meal in Buraimi one night by a strategically judicious pause before saying yes!), and also to Brittany, Ireland, and Languedoc plus two President's trips to Andalucia in 2015 and 2016. Many of these trips, unlike the Canary Islands, involved half-a-dozen or more different hotels, hostels etc. all more work for the organiser, not to mention Jan's pet hate, arriving at a new hotel and trying to get the rooms sorted out with 20 or 30 people hot on her heels, trying to "help" her sort the room sharing out! There were a few interesting moments, like the time in the Pyrenees where we had to explain "yes, 9 men and 9 women, but we need 8 twin rooms and two singles, not 9 doubles, because they aren't couples!" Our Spanish wasn't up to much in those days so we ended up drawing pictures of stick men and women in beds!!! Another time despite telling the hotel firmly that we needed twin rooms, we arrived to find they were all furnished with double beds! "But they can share?" said the receptionist. Oh no they can't, we said and somehow they found enough extra beds!

The 20th anniversary trip to Fuerteventura in December 2017. 

We've had several lost passport, lost wallet, and lost phone incidents, we've had bags pinched from locked vehicles, and on a memorable occasion we were "ashed" when that volcano in Iceland erupted on our final day - no flights home and people with jobs to get back to who had to make a mad dash up to the north coast of Spain for a ferry instead of taking advantage of the accommodation being free and available until the flights started up again.

Despite all the fun and games over the years, when we had a "10 year reunion" in 2007 we realised when we sent out invites that over 250 people had been on trips with us. At 20 years, there must be double that - and some keep on coming back again and again: an amazing record of helping people to see geology in some stunning places! Well done Jan - you are obviously doing something right! "What was that you just said?" "What about going back to Almeria again?" ... watch this space!

The F-island in retrospect - Part 2

Even more retrospectively!

In between writing the first part, and starting this, we've pack up, sold up, and moved to France, so now I'm trying to pick up the threads some 6 months after Part 1, and 10 months after the trip!

Picking up where I left off in April, we carried on from the mirador at Morro Veloso to the Rio de Vega where we walked down the barranco to examine ring complex exposures (see previous trips) and then along the road above, stopping at miradors. 

A pipit?

The information board above Las Penitas dam

A raven at the mirador

Walking up onto the syenite tor above the mirador

The syenite ridge

Agricultural roundabout

A reminder that Christmas is just around the corner!

Ajui 15 December

This is a favourite day, when we walk up the barranco south of the little ex-fishing village to look at the island's ultramafic roots and seamount evidence.

Submarine lava cut by a dyke (bottom left) and zones of migmatisation

There is submarine lava, with pillows, near the entrance to the barranco just south of the village.

Basalt, dykes and migmatite

 Migmatised ultramafic rock is cut by basalt dykes

Zebra rock - the distinctive migmatite texture found here

I really want to know more about the texture and mineralogy of this migmatite - the leucosomes show preferential orientation(s) and have dark edges - depleted melanosome? Plus there are porphyroblasts (or are they restite phenocrysts?) Looking forward to having time to make a thin section of it for myself. Meanwhile I have to rely on information (Woodcock, 2007) that the leucocratic veins are made up of plagioclase feldspar with some smaller grains of clinopyroxene, a brown pleochroic amphibole and an opaque mineral. The finer grained melanosome is clinopyroxene, brown amphibole and opaques. The larger individual grains are cpx, "probably" restite phenocrysts.

Ajuy beach from the south 

When you get back from the barranco there's a fantastic view north up the beach to the cliff at the far end which is submarine seamount series with loads of dykes at the base, then that is planed off with submarine sands planar bedded on top.

Barranco de la Solapa

Heading back inland and turning south in Pajara there's a stop by a road cut where the seamount series are exposed without the benefit of wave washing.

The col between Fayagua and Chilagua

 There are stunning views in all directions from this col, and from the hilltop viewpoint a short walk away.

Parking at the col - popular with tourists

Below the viewpoint (top right) there are lots of dykes cutting across the hillside

Ravens hoping for picnic crumbs

A good place for a group photo at the end of the trip!

After seeing most of the group members off the next day, I stayed on for a little longer as I wanted to check out some ideas for a project.

The F-island in retrospect

A trip in December 2017 immediately before Christmas has now been overshadowed by organising an impending move but it's time (4 months later!) I wrote up a few notes before I forget about it entirely.

First Reccy day

Two days to reccy before the group turned up, so on the first we headed north towards the Tindaya area. I was particularly interested in the origin of some ?fossil shells lying around on the surface and thinking about how they got there. At 170 m ASL it is far too high to have been remnants of past higher sea level.

Tindaya, a sacred mountain to the aboriginal Maho inhabitants of the island, is a trachyte intrusion which has weathered to a pyramidal shape and stand up clearly above the surrounding flat plains.

 A gravel track leads from the village to Tindaya itself where there is plenty of space to park alongside the track. There's a path which goes past some ruined housed and on up to the summit but (Dec 2017) it was closed while some renovation work was being carried out.

The summit track

We spent some time scouring the area for shells and found that, whilst they were fairly abundant below the ruined houses, they were very sparse elsewhere. The shells are coated with pinkish caliche (calcium carbonate) which would have taken some time to be deposited. One of our hypotheses is that they are "kitchen midden" traces from the Maho civilisation.

 We also wondered if they might have been dropped by passing sea gulls - some show signs of predation.

As well as Patella and Strombus there were fragments of mussel shells. If the shells aren't remnants of a kitchen midden, or dropped by gulls, then they might be wind blown or, just possibly, put in place by a very big tsunami - although this is high up, the land slopes gently rom the coast several km away.

The gently sloping coastal plain, looking south from El Cotillo, with Tindaya the conical peak in the distance.

Second Reccy day - 8 December

Then, on the second day we went south from Caleta de Fuste where we were staying. There's a recent lava flow, the Malpais Grande, we were interested in exploring since we'd only managed unrewarding roadside stops here before. This time we turned right off the FV2 onto a track which leads westward in the direction of Tiscamanita.

The Malpais Grande where lava from the Caldera de Arrabales (far right) has flowed over a very level area which might have been an ephemeral lake bed in the past.

Pebbles of calcrete cemented by caliche

The level Tuineje plain with a recent lava flow on the right.

One of the recent scoria cones is being actively quarried (no entry!), which explains the excellent track up to this point!

 We went on a km or so past the quarry to see what it was like but the track soon becomes rocky and rutted - not a place to take a convoy of 5 cars - so we returned and stopped a couple of hundred metres short of the quarry entrance to take a look around.

A disused aqueduct built of random blocks of lava (dark) and caliche crust (pale buff).

The old aqueduct, with the working scoria quarry in the distance. The square structure where Jan is standing looks like an old stock pen or hut.

What we did find of interest by the stock pen was an old well, with water good way down (some stone dropping went on to check) showing that the water table, in winter at least, is accessible for agriculture etc.

Bearing in mind yesterday's hunt for fossil shells I had a good look around but only found this single Patella

 Continuing south we were keen to find the "new" way to the Strombus bubonius on the raised beach at Playa Matas Blancas. These are evidence of former higher sea levels and a warmer climate. Since we were last there a new road has been built to the resorts at the southern end of the island and the old road bypassed which disorientated us but after an initial search on the wrong beach we found it! At least we didn't have 20 people following us when we missed the way.

The Strombus bubonius site at Playa Matas Blancas. Nice "soft" protection and there's an information board up on the stone at the back of the beach.

Playa Matas Blancas and the Strombus bubonius site

We finished the day's reccy with a visit to the beaches either side of Punta de Guadalupe on the north coast of the Jandia isthmus. It just happened to be lunchtime as well so we were pleased to find the cafe was open (it looked a bit shut originally but that was just because the strong wind was keeping people inside!)

Raised beach at Punta de Guadalupe

More raised beach - there are about 5 generations of deposits (lava, beach, caliche etc) which take quite a lot of unpicking but is good brain and observation exercise!

The next day we spent shuttling back and forth to the airport - thankfully only a 10 minute drive away - and getting people sorted out and settled into accommodation, before a slightly lazy start the following morning to accommodate some who had arrived well into the evening, and some who wanted to pop to the supermarket for the day's sustenance.

First field day - Ajuy, Puertito de los Molinos, Corralejo dunes

Crab on the rocks at Ajuy

Lava flows interbedded with marine carbonate sands by the lime kilns at Ajuy

Cross stratified marine sands overlain by pillow lava and a flow - far side of Caleta Negra, Ajuy

More of the same

The fantastic exposure at Caleta Negra - Greenish, altered rocks of the Basal Complex planed off by a marine abrasion platform then overlain by marine carbonate sands and a lava flow.

Then it was on to Puertito de los Molinos for lunch and some real genuine field work. There are some spectacular dykes here, cutting Basal Complex gabbros, and exposed in the bottom of the barranco at the back of the beach. What's more, they are supposed to come from two generations of extension, of slightly differing directions, and the whole complex was rotated in between injection of the first and the second batch so that the early ones dip steeply but the later ones are vertical.

Beautiful clean exposures show up glassy, chilled margins so well

A close up of one of the dykes shows the gabbro and porphyritic basalt textures.

Some of the basal complex rocks are altered hyaloclastite breccias.

As above, only a close up!

We finished off the day (after tangling with yet more new roads which didn't go where we wanted them to) at the Corralejo dunes where we braved the wind to experience aeolian sand transport in action and see the ripples forming.

Corralejo dunes

Second field day - Malpais Grande, Gran Tarajal, Playa Matas Blancas and Punta de Guadalupe

We began with a trek across the Malpais Grande's caliche plains and lava flows to look at the quarry, and the well and aqueduct, that we'd reccied and made time to stop as we got back to the main road to look across to Los Arrabales breached scoria cone.

Los Arrabales from the FV2 as we headed south towards Gran Tarajal across the Malpais Grande

Los Arrabales - a good viewpoint to have discussions about wind directions, breached cones etc

Parking by the harbour in Gran Tarajal gives a good view of the shield volcano structure in the cliffs on the far side of the bay; we stopped for a coffee before taking a closer look,

Sea-front art in Gran Tarajal

Gran Tarajal mural

Fishing mural in Gran Tarajal

That headland, over there.... Punta de Piedras Caidas

More prom art

An interesting drive through the middle of Gran Tarajal and out on the eastern side, past the football stadium got us to the headland, the Punta de Piedras Caidas, a short, easy walk down a cobbled beach. This is composed of gently dipping lava flows, with intervening palaeosoils.

This annotated photo shows the dark lava flows (coladas) and red palaeosoils (almagres) at Punta de Piedras Caidas. From Ruiz, R.C. and Cabrera J.M.T. (2011) Inventario de recursos vulcanologicos de Fuerteventura. Available at http://visitfuerteventura.es/wp/wp-content/uploads/Inventario_Volcanes_web.pdf (accessed 16/4/18)

The lava on the headland is part of the Central Shield Volcano (CSV). Very vesicular with mineralisation in the vesicles

Close up of a fallen block at Piedras Caidas, we wondered if the reddened, fine grained, angular clasts were 

part of a reworked palaeosoil?

Final stop of the day was the beach at Punta de Guadalupe where the group had the task of sorting out how many generations of raised beach (from the various exposures of lava, cemented beach sand, and caliche) they could actually identify.

OUGS in action..... is this on top of that or is it a bit of the same one?

Arty bit - the stream at the back of the beach

G heading purposefully towards the next exposure!

Punta de Guadalupe exposes marine sandstones, and dune sands, over a raised abrasion platform

Heading back for a coffee across the jumble of volcanic and sedimentary rocks!

Shield volcano erosion on the way home

Still thinking about the caliche crusts that exist over so much of the island I kept an eye open for likely sites where I could investigate further around the relict "cuchillos" - knife edge ridges that are all that remains of the central shield volcano

The upper ash and lava layers are clear here but much of the lower slopes are obscured by talus which have been dissected into cones by V-shaped valleys

Here the V-shaped valleys extend right up to the ridge and summit

This hillside to the north of the Malpais Grande looks as though the talus areas may have a caliche crust

An isolated hill, again with the telltale light buff colour showing through scrubby vegetation

The caliche is much clearer here on talus "flatirons" stretching halfway up the hillside

And the caliche coated flatirons show up clearly in a close up view.
The unconformity between the lower and upper lava flows shows to the upper left.

There was definitely some food for thought here - something to investigate after the OUGS group had left at the end of the week! Just to finish off a good day, we were greeted by a rainbow when we got back to the hotel.

Strong winds and lime kilns

A walk south from Caleta de Fuste 

Looking back to Punta de Bajo

The wider view of Caleta

Big waves and palm trees getting windswept

Between Caleta and Las Corcobadas is more natural - no imported sand nor breakwaters, just blocky lava and sand.

There's a series of moles built out to protect bathing areas, and each has its chiringuito or restaurant at the seaward end

No bathers today - the December wind was strong and chilly!

The sea flooding over the approach to the restaurant

Sun loungers stacked and tied down

At the southern end of the promenade, Caleta de la Guirre, are some kilns - Hornos de Cal. I'm guessing that, in the absence of carbonate sediments in this part of the island the most likely source of lime was the thick caliche crust.

The beach by the Hornos de Cal de la Guirre

Lime kilns

Lime kiln

Lime kiln

Field day - Morro Veloso, Betancuria, Vega ring complex

The track and roadside exposures just below Morro Veloso - matching up plan views and sections of dykes

Dykes in Morro Veloso road cut

Displays in the mirador

This section was particularly interesting as it showed ground water reservoirs, which tied in with the well we found at the Malpais Grande. (It does rather remind me of a poppadum cooked in the microwave!)

To be continued...