Threlkeld Mining Museum

Saturday morning on the OUGS winter weekend at Shap Wells and a group of us headed off for the mining museum at Threlkeld. I was really looking forward to this as last time I'd been to Threlkeld Quarry, near Keswick, was soon after the quarry had closed down in the very early 1990s.
That occasion was one of Mike Henty's 'Geolidays' - we stayed in self catering cottages on the edge of Keswick, Mike and Linda did the cooking - amazing barbecue cookery - every night and Dave Williams and Dee Edwards were there to help us with the geology. The aim of the week was to check out Threlkeld quarry so that the group hoping to set up the mining museum had some pointers to some of the interesting geology there but we also managed a good look around locally, partly under Eric Skipsey's guidance, including the Borrowdale volcanics.
The stunning Skiddaw slate xenoliths in the Threlkeld microgranite, and the beautiful example of a granite/country rock contact we found on that occasion are still the 5 star geology exhibits on a tour around the quarry but there is masses of other stuff to see there too: excellent displays of local geology, much in the way of quarrying and mining machinery, a narrow gauge steam railway to take visitors around the site, and an underground tour of an old silver, lead, zinc and copper mine that was here.
Our guides were very knowledgeable and their enthusiasm was impressive! A smashing morning.

Last day on the F-island

On the final day we decided to head for a corner of the island we'd yet to explore - the SE, between Caleta de Fuste and Gran Tarajal. This is an area of cuchilletes - remnants of the central shield volcano - and scoria cones and flows. It is also the closest point to the African mainland so we headed first for the lighthouse on the south-east tip. This stands on top of a cuchillete - one of the few places where a road goes to the top of one of these knife edge ridges and as we drove up the single track road we began to see why: it wound around the hillside spurs with a steep slope below. Occasionally on the most dramatic points there was a token crash barrier but for the most part nothing between us and the drop and we were glad not to have to pass anything in one of the passing places!

Looking back at the lighthouse, and towards Gran Tarajal, from the headland

The road back down - we were glad not to meet anything!

From here we went on to Gran Tarajal which has a lovely beach and uses a very pretty stone for some of the buildings

Gran Tarajal

Leisegang rings in stone

Finally, as the icing on the cake we had a great view of a Fuerteventuran Chat while we ate our picnic!

More reccying south of Ajui

With just Jan, Gill and me left, after some serious work with Google Earth images, maps and GPS we decided to have a go at finding the carbonatite exposures south of Ajui and the migmatite in the Barranco de Aulaga so that we'd be better prepared for future trips. First off, the carbonatite: we followed a rather circuitous path around and through some new villas that seem to have been abandoned in mid-build and made our way out to the headland. There seemed to be some 4WDs probably belonging to fishermen, so we aimed for those hoping that there would be a way down to the shore platform below the cliffs. There was, but only for the more agile and longer legged (specially the bit where the directions say to 'cross a 2 metre wide tidal gully'... ! We three elderly ladies decided to view from afar but at least I can take people there so they can have a look if they want.

Punta de Nao, south of Ajui.

The carbonatite could well be some of the lighter bits here!

Giving that up as a bad job, we trekked back over the ridge into the Barranco de Aulaga to see if we could find some more tumbleweed to attack Gill, and perhaps some carbonatite further inland. On the way we happened to spot something I'd seen before and think were bee nests in the caliche coating over the hillside. They look rather like the bowls of old fashioned clay pipes. If anyone knows do say! (Later... Jesus, on the Iberianature forum , says that they are wild bees - and to keep away in spring and summer! ... and later still ... that they are Family Halictidae, genus Halictus or Lasioglossum)

Burrows or nests in caliche

Geology in the making in the Barranco de Aulaga - mud cracks and rain drop marks

Epidote crystals on a basalt joint face

 So - plenty else to look at but we still hadn't found the carbonatite (later checks with grid refs and Google Earth show that it is quite a way up the hillside so we were in the wrong place)
However we did find something we'd been looking for all week - a close up view of pillow lava in the submarine volcanics!

Good shape, chilled margin all around - has to be! 

Tomorrow - last day - the closest point to Africa!

The Majo sacred mountain and the north coast

Montana Tindaya

The pale coloured peak of Tindaya, near La Oliva, was a sacred mountain of the indigenous Majo people. Even today a permit is required to access the summit area. The rock itself is much more felsic than most, hence the paler colour.

Pliocene sea floor

Tindaya's lower slopes are blanketed by Pliocene marine sediments deposited during a period of higher sea level. There is good evidence in the numerous sea shells.

 On the coast to the west, near an abandoned urbanisation, are some superb exposures of the seamount series rocks, unconformably overlain by subaerial volcanics and some marine sediments

Lobos from the road west of Coralejo

 A graded track runs along the north coast - a little bumpy but perfectly drivable - and it has great views north towards Isla de Lobos and Lanzarote. In between the a'a flows from the chain of scoria cones to the south there are beautiful little sandy coves

Peridotite xenolith in basalt

 North of Coralejo harbour some rock armour contains beautiful mantle xenoliths, such as this one made up mainly of fresh and weathered olivine and plagioclase feldspar

Cats getting warmed up on some cosy basalt!

South of Caleta de Fuste

We'd heard that the 'Salt Museum' was worth a visit so headed for it this morning. It is part of the chain of state run museums on the F-island - some are free and some charge a basic €5.

Las Salinas de Carmen, Caleta de Fuste

 The Salt Museum has an exhibition hall explaining the history of salt production and the salinas here; once we were genned up on that we followed the trail out around the foam collection tanks, heating tanks and evaporation ponds before picnicking in one of the shady shelters with stripy Barbary Squirrels for company.

Barbary ground squirrel : Arrdilla moruna : Atlantoxerus getulus. This was introduced to the F-island from the mainland in 1965 and has settled in well!

After lunch we headed to another of the museums, the Poblado de la Atalyita. This is a majo village which was inhabited by the indigenous people of the island before the conquest and lies on the southern edge of one of the a'a flows that run down to the coast here. The flow ran past a small conical hill known as La Atalayita 'the little watchtower', hence the name of the village. The houses themselves are dry stone huts built of rough blocks of a'a lava.

Looking south across the a'a flow (the Malpais Pequeno). La Atalayita is the low conical hill on the left. The village lies to the right of this, on the far side of the flow

A ruined stone hut built of blocks of lava. Jan for scale.

To wind up the day we went on down to the coast at Pozo Negro where we found a lovely restaurant right at the back of the beach and enjoyed sitting there for some time watching fishing boars being launched.

Fishing boats are launched straight off the beach at Pozo Negro. The nets (there are two here) are taken about a mile offshore

To wind up a good, varied day, as we drove back along the side of the Malpais Grande we saw a dozen or more Egyptian Vultures circling above the cuchillete on the northern side of the valley. Sadly too far off to photograph :(

Alcogida Eco-Museum and exploring Puertito de los Molinos

We'd checked up on the Eco-Museum a couple of days earlier and all of us fancied a look around it so all 6 of us headed off therein time for 10 am opening. It was well worth a visit with tradition houses restored - from very basic ones to the main farmhouse in the village; added to that there were plenty of displays of crafts - embroidery, stone carving, weaving, basket making, bread making (we sampled that and it was very good!).
A few geological highlights:

Building stone: light coloured Pliocene sedimentary rock (the odd bit of lava seems to have crept in) with quoins of red cemented scoria from nearby Mta Bermeja.

Lumps of scoria are hammered into the bottom of wooden boards to make a threshing sledge.

The stone mason carving a mortar: he had a three sided shelter so that he could always keep out of the sun... neat!

Pestles and Mortars carved out of volcanic rock

 After calling in at the Visitor Centre to buy some fresh baked bread we went on down to Puertito de los Molinos where we'd heard there was a good fish restaurant at the back of the beach and we weren't disappointed. We were then thrilled to see some lovely exposures of volcanic lavas cut by at least 2, possibly 3, sets of dykes.

Back to Ajui

Numbers halved after the departure of 6 of the group for the UK we decided to pay a return visit to Ajui to have a look for the migmatite in the contact metamorphic aureole of the pyroxenite intrusion. Sources described this as visible in the Barranco de Aulagar to the south of the village
We parked at the top of the village (saved going back up the hill again) and headed for the barranco which didn't look as though it had seen any water for some time though obviously there had been much more regular flow down it in the distant past. The route took us up the western side of an earth dam (which held back no more than a dampish infill of mud where some greenery was growing.
A couple of hundred metres further on we began to find the migmatite: this is formed when the heat is so great that the rocks, instead of being metamorphosed, begin to melt. First thing that happens is that some of the lower temperature minerals are sweated out of the groundmass, coalesce in any areas where there is space (in this case probably cracks created by shear parallel to the dykes) and then recrystallise as things begin to cool down.

Barranco de Aulaga looking upstream (S)

Migmatite

The pale, felsic minerals show as light streaks in the darker groundmass.
Aulaga is the Spanish name for various thorny plants, in this case Thorn Lettuce (which I've also known as 'chicken wire bush' because of the 120 degree angles of the thorny stalks). Rounded masses of this were blowing down the barranco in the wind - the original tumbleweed perhaps? - and one of the group wearing shorts got badly scratched when one made a beeline for her!
After some first aid, followed by a fish lunch at one of the beach restaurants we decided to go and have a second look at the southern end of the Barranco de las Penitas which we'd been to a few days before: Jan reckoned that we could actually drive the track to the far end, saving a hot walk, so that we could get close to the syenite outcrop at the southern end of the ring complex. She was right.

Malpaso - the southern end of the barranco de las Penitas

We were able to walk along a pleasant path and through a palmera (sadly a number of trees are dying but there is a project to restore them) to the southern end of the syenite ridge a short way below the hermitage. A good reccy for next time!

And then there were 6...

 With the departure of the 1-weekers that just left Ann, Sally, Greg, Gill, Jan and myself.

Jan, Sally, Gill and I decided to catch the ferry from Corralejo over to the Isla de Lobos for the day

Several boats go back and forth, some with 'glass bottoms' though when we looked you couldn't see anything very exciting!

Lobos has one large scoria cone volcano, plus lava flows

El Puertito is a small fishing hamlet which boasts a restaurant - order your meal on arrival and they will tell you what time it will be ready to come back and eat! We had parrot fish

El Puertito

A'a flow from the scoria cone is puntuated by hornitos - bulges where gases expanded beneath the crust of the flow

While Jan and Gill went off for a walk to explore the island, Sally and I relaxed in this sheltered cove and enjoyed a swim

A fun day out at the end of a busy week!

Last day for the 1-weekers: Pajara to Punta de Guadalupe

Slight problem with today - I needed to make space on the SD card and stupidly deleted the images before I'd saved them to my laptop. duh. Still, its a good excuse to go back ;)
We headed west to Pajara, stopping for coffee and a bit of tourism in the town. The church is lovely, with 'Aztec-style' carvings around the doorway and the noria (water wheel) just opposite was being demonstrated by an elderly Majorero (Fuerteventuran) and his burro.
From here we headed south and had a splendid view of Mta Hendida where subaerial basalt and trachybasalt lavas sit unconformably above an erosional surface in the basal complex seamount series. The older shield stage lavas are completely absent so 3 Ma worth of rock has gone, perhaps by flank collapse.
A winding road led up to a mirador on the col between Hendida and Sisacumbre with some exceptional views and at least 3 options for a stunning lunch location. Just down the hill from here we stopped at a T-junction to examine an exposure of dykes cutting green, altered basalts of the seamount series... still playing 'spot the pillows' though they hyaloclastites are fairly convincing!
Finally we headed down to La Pared and through the urbanizacion to the Punta de Guadalupe where, after a coffee stop, we went down onto the beach to look at the weathered breccias from subaerial cones that make up the shore platform. These are thought to represent the transitional stage from seamount formation to the point where the volcano broke surface and became an island. Shiny brown palagonitised surfaces were also much in evidence here.

A fantastic location to end the week on... though I'd saved some goodies for the 5 who were staying on for another few days.

Day 5 The Jandia Peninsula

Our guide book - Carracedo and Day's "Canarian Volcanoes" - warned that this could be a long day but it was not such a long drive as we had been led to expect: perhaps the roads have been improved in the last 10 years?
We headed south past Gran Tarajal and Tarajalejo onto the Jandia isthmus where we made our first stop to look at the carbonate sands that cover this area and compare them with those we'd seen at Corralejo which have a similar origin. Looking for somewhere to pull off the road our lead car was perhaps a little hasty - we hit a patch of soft sand and had to be pushed back onto something a tad firmer before we continued! In the excitement I forgot to take any pix :(
We went on to the next recommended stop in Valle de los Canarios: the access is a little convoluted since it involves going past the valley mouth, off the dual carriageway, round a couple of roundabouts, back the way you came and under the main road. By this time we were ready for a coffee and stopped at a filling station. There was a good exposure of the shield basalt lava beside the cafe which was rather fortunate since when we came to drive up the valley we found that the road was barred with a locked gate and the alternate access ended in a farm yard.

The lava flow by the cafe

Subaerial shield basalt in close up: phenocrysts of black pyroxene, white plagioclase feldspar and orange, weathered olivine.

 Continuing SW along the coast we stopped at the mouth of another of the broad valleys that have been eroded into the flanks of the Jandia volcano where we had an opportunity to look around at loose material on the ground as well as at the sections through the volcano that are exposed in the valley sides.

A valley eroded into the SE flank of the Jandia shield volcano

Northern valley wall: there are supposed to be two phases of eruption, separated by an erosional unconformity. We saw some evidence of this around the island

Dykes intruding lava flows in the headwall of the valley. These would have fed later eruptions

 From here we went on to the Degollada de Agua Oveja: a graded track leads up and over the arcuate ridge which is all that remains of the Jandia volcano. Most of it has disappeared NW into the Atlantic - perhaps in one mega flank collapse but more likely in a series of smaller slips. The scar is impressive... provided you can stand upright long enough to admire it! The wind was ferocious!

NW Face of what remains of the Jandia volcano

Jean, Jan A-J (the trip organiser) and Gill braving the wind at the top of the pass

 By now it was lunchtime so we continued west to the little fishing village of El Puertito  where we found a cafe where we were able to sit out of the wind.

The beach at El Puertito is cut by dykes

Faro de Jandia from El Puertito

Beach-comber art at El Puertito

 Finally we made our way to the lighthouse on the headland, though unfortunately as it was a Monday the exhibition wasn't open.

Jandia Faro

Dunes in the lee of bushes Punta da Jandia

A longish drive and, perhaps, less of geological interest than in some other areas but the views, and the topography are stunning! Well worth spending a day there.