12 November 2006

A Short Journey to Bolivia and Peru

My travelling companion was my daughter Anna. We joined a segment of the Exodus 'South American Explorer' overland itinerary.


With Anna on the Salar de Uyuni
Day 1 - 28 October


9 hour flight from LHR to Miami on an underwhelming AA flight. Transferred baggage to next flight having cleared immigration and took cab to get some lunch at Miami Beach.
Quite a small city really, albeit with much new construction underway, taking the freeway to South Beach with views to the Downtown and Harbour Bay areas. Had a quick look at the (nondescript) beach before walking the ´strip´ to find a restaurant for lunch. Art deco buildings, with an odd assortment of highbrow and downmarket venues all peddling similarly themed food. Settled on a Cuban restaurant and shared a plate of grilled fish before getting a cab back to the airport, this time detouring to have a better look at Downtown and areas to the north. Passed various islands with very large houses, one belonging to Gloria Estafan, with large boats moored nearby.
An interminable wait at Miami for the La Paz flight, but did, eventually, get that all important upgrade! We ignored food and went straight to sleep before waking to see dawn breaking over the Amazon to our left and spectacular views to the Cordillera Real to our left…a fine vista of 6000m snow capped peaks north of La Paz. Then over the barren altiplano to land at El Alto, the highest commercial airport in the world at over 4,000m. Arrived 0630 after a 6 hour 20 mins flight – 31 hours of travel so far!


Day 2 - 29 October


Met by Carlos, William and driver Estoban of ´Tours of Bolivia´. Carlos is a renowned Andean mountaineer, but left us in the hands of William, a very knowledgeable 36 year old guide, who studied tourism at university for 5 years. Into an ageing 4WD, we passed through El Alto, a rapidly expanding commuter suburb above La Paz, and headed south across the altiplano at an altitude of between 3,500 – 4,000m. Sudden moves produced a racing heartbeat and shortness of breath! 



Crossing the Altiplano at around 3600m
We passed through many small towns and villages, where people eke out a largely subsistence living, growing potatoes, millet, vegetables and raising llama for meat and wool, plus cows and sheep. A very poor people, still using ox-drawn ploughs, washing clothes in rivers, etc, although 100,000 of them commute from El Alto each day in search of work.
Big skies, distant lakes shimmering in the clear light, a thunderstorm producing intensely contrasting light to the east and seemingly barren landscape which is, in fact, very fertile.
A breakfast stop, great OJ, chicken sandwich etc., before moving south to Oruro, the biggest settlement on the altiplano with a population of 200,000 but now a shadow of its former self (a major silver and tin mining area), but with intriguing sculptures made from scrap metal and one of the most famous of all S American festivals held in February each year.
Onwards to Challapata for a quick lunch of sevaruho soup (made from a local grain called quinoa, which has an exceptionally high protein content).
As we travelled further south from here, the tarmac quickly ran out and we drove on wide, reasonably well graded gravel roads, moving across increasingly arid and deserted country. Outcrops of lava sills to the east, many ghost towns (whose previous raison d´etre was to service the railways carrying ore from the south).


South from Oruro
Passed Lago Poopo, much diminished due to evaporation (more impact of global warming), to the west, saw sand dunes that didn´t exist 10 years ago, and huge expanses of graminea , a local grass that grows in conical tufts. The roads were bordered by dhola, a bush with a pungent resin, used for fire making. Spotted a lone flamingo on a patch of salt lake.
Volcanoes and subsidiary vents seen all the way to Uyuni, particularly to the east.
A long drive, we could feel the intensity of the UV radiation at this altitude, and we were much relieved to finally reach Hotel Girasols, three blocks away from the market area of this dusty town in the middle of nowhere! A town now very dependent on tourism, with the demise of the local mine at Pulcayo.
Quote of the day…on dust: ´a communion with Mother Earth´ !
A very tiring day – about 41 hours door to door, but the anticipation for a great trip ahead unabated. A quick walk into town, a good pizza and bed by 2040!


Day 3 - 30 October



Breakfast at the hotel including our first taste of coca tea (rather like green tea really), and then off to visit the magnificent Salar de Uyuni, the highest and largest salt lake in the world, lying at 3,650m and twice the size of Great Salt Lake in the USA, with an area of 100,000 sq. km. The depth of salt is normally between 2-20m. It’s an awesome spectacle as you first approach the edge of the salt lake, about half hour outside the town. Passing through a small hamlet where everybody derives an income from salt - either for industrial use or table salt (where it is processed with addition of iodine to eliminate goitre, traditionally a big local health issue) – we sped across the pan in a 4WD for our first stop at a now abandoned hotel, the Hotel Playa Blanca, constructed from salt blocks and roofed with thatch. Abandoned as effluent was polluting the salt pan, but certainly a great location, more so than the newly constructed salt hotels being finished on the edge of the pan nearby.


Hotel Playa Blanca
First view of the magnificent Salar de Uyuni
We stopped to view the ‘ojos de sal’, which are the breathing spaces for subterranean rivers flowing under the Salar, and spectacular shows of crystalline colours on a surface covered in pentagonal and hexagonal shapes. These areas are to be avoided when driving across the lake as they can be very deep. In the smaller holes you could pick out perfectly cuboid salt crystals forming on the sides.
Our next objective was Incahuasi (literally ‘Inca lodge’) – an island of volcanic origin, formed of pyroclastic lava and since covered in coral from ancient seas and now fossilised. Also known as Isla de Pescadores, it is about 80km from the hotel, and emerges like the back of a fish (hence the name) as you approach and the curvature of the earth reveals the view as you get closer. Incahuasi was used as a resting place for the Incas who used to cross the lake with llamas loaded with goods for trade in Chile (border about 150 km to the west) and beyond. As you draw near to the island you start to see hundreds of the giant columnar cacti, many of which exceed 10m in height, with the oldest specimen 1,203 years old!





Trick photography on the Salar de Uyuni
There’s a small café and hotel on the island, with thatched roof and coral walls. A circular tour path takes you up to the highest elevation, amidst the cacti, and this gives you spectacular 360 degree views of the blazingly white lake, occasionally punctuated by some of the other 60-odd islands, all remnants and products of extinct volcanoes. There were distant views to glacier topped mountains to the west and the 5,400 m Volcan Tunupa, our next objective to the north.










Views from the Isla de Pescadores (incahuasi)
The drive took about 90 minutes, with my daughter Anna and I taking turns at the wheel. Arriving at the base of the volcano, we crossed a waterlogged fringe area with foreshortened views of the gigantic crater, rocks grey and red from the past inferno. There were many llama and vicuna about as we ascended a steepening gravel track above the small village of Maya, climbing about 300m to view a tomb containing the remains of a mummified family. The father, obviously an important man, had died and, in the custom of the (pre Inca) times, his family were required to die with him. It was a bit spooky looking at a whole family in mummified form.





Mummified family, at cave near Maya, next to Volcan Tunupa 



Stumpy on the Salar de Uyuni
On the way up to the tomb we saw a condor in the distance (unfortunately now very rare), and another form of columnar cacti, this time with red flowers. Great views down across the salt pan, where we spotted a small group of Chilean Flamingo (yellow legs), before returning to Uyuni across the salt. We had some fun with photography, exploiting the intense light of this amazing natural feature.


Salar de Uyuni from Volcan Tunupa
Returning to Uyuni we stopped for a quick look at the graveyard for late 19th century steam engines and assorted rolling stock. Rusting away in the bright sun of the altiplano, this is the legacy of Uyuni’s mining heyday. Back to the hotel, farewells to our two guides and a quick supper at the Kaktus restaurant – llama steak, spag bol and a couple of drinks $20…a bargain! Internet café, hotel, bed!


Railway graveyard, near Uyuni
Uyuni


Day 4 - 31 October


Off at 0800, courtesy of Chris and Suzi at Tonito Tours in Uyuni, with ageing driver Ishmael. Steep pull eastwards on gravel roads, passing through a military checkpoint to enter the virtually deserted mining village of Pulcayo. Up and up, crossing a number of passes, one at over 4,190m, amidst spectacular scenery which changed completely every 15 minutes as we travelled through yet another geological zone. Rolling pampa, many llama and vicuna, eventually seeing more goats and pigs as we neared Potosi. Volcanic outcrops, lava flows, sand dunes, canyons (with a quick lunch next to the river in Rio San Juan) and immense landscapes in all directions. Very little habitation here – the odd village like Ticatica – but mainly clusters of farms near watercourses, where isolated but very green trees, mainly willows and a cypress type tree, grew. Some very wide river valleys, dry at this time of the year (the rainy season starts late November), with pampas grass surviving in the river bed.
A long, winding and frequently exposed gravel road, taking us about 5 hours to travel, only enlivened by the wandering attentions of our driver, which gave rise to a few heart-stopping moments on the more exposed sections!


On the road to Potosi


We finally reached Potosi, the highest city in the world at 3,977m, a bustling town of narrow streets with brightly painted houses. There was some confusion over hotels, so we booked into the Hotel Santa Teresa, close to the main city square, the Plaza 10 de Noviembre. Towering over the city is the 4,824m Cerro Rico (Rich Mountain). At the end of the sixteenth century Potosi was the biggest city in the Americas and one of the richest in the world, rivalled only by London, Paris and Seville due to silver mining on a grand scale. The annual average temp is 9 degrees C!
Mine tours can last about 4-5 hours and are said to be ‘physically and emotionally draining’ – mine entrances are above 4,000m and the walking/crouching can involve breathing noxious gases and seeing people working in appalling conditions in temperatures up to 40 degrees C (miners get first degree silicosis after 5 years and are untreatable after 15 years). Needless to say, the miners are avid users of coca.
We decided to go for a shorter tour with tour guide Banoa, formed three years ago by an ex-miner (and avid coca user). We took a short taxi ride to the miner’s area and were provided with protective clothing, wellies, and helmet with electric light pack, before being led to purchase gifts for the miners we would see working. A ‘one stop shop’ found us purchasing bags of coca, cigarettes – and, amazingly, sticks of dynamite, ammonium nitrate, fuse wire and detonators!


Coca gift for the miners at Potosi
Cerro Rico, Potosi
Potosi
'Tourist' entrance to the silver mines at Potosi !
Then up to the mine on appalling access roads to watch our guide give a demonstration of how to produce an explosion…he calmly lit the fuse, handed the charge to me for a very brief photographic moment, then ran up the hill to place it into a hole in the side of the mountain, seconds before the charge exploded with a tumultuous bang.
This experience was accompanied by a little coca chewing. Placing the leaves inside your cheek and allowed to slowly soften to release the juices after 10 minutes or so, ash was then introduced to catalyse the chemicals in the leaf, given rise to almost instant numbness on that side of the face. A strange experience, and not one I’d be particularly bothered to repeat. But, apparently, chewing coca suppresses the appetite and enables the miners to work for long period without exhaustion.


Miner adds detonator to a stick of dynamite
Stumpy in a moment of madness, holding a stick of dynamite with the fuse already lit...
And the result...
After that we were up for anything, except the mine entrance was very foreboding – a hole in the side of the hill, with crude pit props and compressed air pipe work randomly suspended above our heads. Into the tunnels, quite low in places, with huge unprotected holes on either side of the path, which will have served as ventilation shafts or access holes for ore to be taken out of the mine for processing. Several hundred metres in, we came across a miner, working on his own in a hole, painstakingly pushing explosives into nine holes (each 20 cms deep) that he had spent the previous two days drilling by hand. After an hour or so, we all retreated 50m back up the tunnel, to be followed by nine thunderous bangs, each accompanied by a shock wave that pummelled the ears. No wonder these guys chew coca.


Miner rodding dynamite charges into the rock
Local woman with coca
As we turned towards the exit, we were persuaded to drop down into another shaft to view a ‘museum’, the main feature of which was a small chamber dominated by an effigy known as ‘El Tio’. This figure had a huge penis, was covered in coca leaves and had a cigarette stuffed into its mouth, all offerings given by the miners at the end of the Friday shift to pay homage to the god of the mine. Whilst they do this they also get smashed on 90 degree spirit before going down to the town for more…not very different from the old mining towns in the UK methinks!


El Tio
A short description of the mining is called for. The ore is a complex blend of silver, tin, lead, and zinc, found in seams amidst granite and volcanic lava. Some of the walls are covered with a crystalline form of arsenic…an inhospitable place indeed. Each miner is a member of a cooperative, and will normally employ less experienced men (and his own family during school holidays) to man-haul the ore to the surface. 15% of his proceeds go to the coop and 4% to the state who provide basic health care and old age provision. They make a living, occasionally a very good one if they hit on a seam of ‘red silver’, but their income depends entirely on the quality of ore they extract.
Returning to the hotel we later met up with the Exodus overland group we were to spend the next week or so travelling with. They had started in Rio de Janeiro some six weeks earlier and had recently come up through Chile. A good dinner was had at the restaurant El Fogon, but with appetites tempered by altitude and jet lag.


Hotel interior, Potosi
Day 5 - 1 November


Awoke feeling groggy for the first time, the first effects of altitude, probably not helped by red wine the night before. Had a walk up into the town, visiting the ornate mestizo style tower of the Jesuit Compania de Jesus Church where we climbed a very tight spiral staircase up to the bell tower, to get great views over the city. We then did a quick walking tour of the city and some people watching in the Plaza 10 de Noviembre, before taking a tour of the Casa Nacional de Moneda, one of eight gold and silver coin mints established by the Spaniards in South America. It’s an impressive building and we had an amusing tour with a slightly eccentric guide – paintings, coins, dies and presses. A good lunch in the Internet Café Calendria, then a short walk around the town in lovely warm sunshine. Evening dinner with the group and a bar whose walls are covered in graffiti from overland groups and assorted travellers.


Day 6 - 2 November



Met group and breakfasted in the Hotel Jerusalem before boarding our truck (‘Pope 6’) for the long drive, thankfully on tarmac, from Potosi to La Paz. We set off at 0800 and quickly we were passing through spectacular canyons and mountainous country again. Very few signs of life out here, although groups of families were clustered in cemeteries today to celebrate the ‘Day of the Dead’. We passed through tracts of country where the rocks and soil were a light shade of green, probably evidence of copper, before reaching Challapata where we had stopped for lunch on our first day in Bolivia. Then north towards Oruru on a relatively flat road, with Lago Poopo to our left. A lunch stop in the middle of nowhere, then on again until a succession of tyre problems happened upon us – a blown tyre wall, a blow out in the replacement tyre, and finally a puncture in the replacement for that, as we passed through the rather dodgy El Alto township above La Paz. All in all, this added three hours to the journey, but time was passed with a good book (recommended - ‘The Boy in the Striped Pyjamas’), quizzes, and some hilarity with a Quecha woman who was married to a tyre repairman who helped us some 2 hours south of La Paz.


Lunch stop between Potosi and La Paz
Wacky Quecha lady and Stumpy
Passing through El Alto with the cabin lights turned off (so as not to attract attention to a bunch of ‘wealthy’ gringos in this rough part of the city), we eventually reached La Paz, fantastically situated in a deep canyon 350m below the altiplano. 


El Alto
We reached the hotel, Estella Andina Hostel, at 2100, before having a very good (but quick) dinner next door.
Traveller’s note: iPods do not function well above 3,000m, and even if you do get them working, they frequently fail when you get back down to lower altitudes…you have been warned!


Day 7 - 3 November


La Paz! Awoken by peeping horns everywhere. The hotel, situated about two blocks from the famous ‘Witches’ Market’ in Linares, is very friendly and efficient, with each room individually painted in frescos of Bolivian scenes – ours of Potosi, with a picture of Cerro Rico and another of the entrance to the Mint concealing our bathroom door. The hotel also has internet facilities.
After breakfast, we took a short walk down to Linares and Sagrnasa streets before an informative visit to the Coca Museum, which was well presented and interesting. Then back to Linares for some shopping, including an oil painting from a gallery close to the museum. 




We paid a quick visit to the bustling Plaza san Francisco before rejoining a few of the group for lunch at ‘Pot Colonial’ on Linares. Waited a hour for our drinks, then another 30 minutes for food of poor quality. A completely shambolic place to eat…not recommended.
We took a three hour city tour in the afternoon, first heading out to the Valle de la Luna, an area where mud has dried, then eroded into fantastic pinnacles and canyons. Weird. It is also overlooked by the world’s highest golf course, Mallasilla GC. 




Valle de la Luna, La Paz


Going back into the city we passed through the wealthier suburb of Calacoto, before stopping at the main square, Plaza Murillo, a busy place full of pigeons, surrounded by fine buildings on all sides, including one riddled with bullet holes from the 2003 troubles. Here we saw the Palacio Presidencial and the Congreso Nacional buildings, before walking up Indaburo, past the Teatro Nacional into Calle Jaen, an area with some fine colonial architecture. A quick visit to the Museo de Metales Preciosos (the ‘Gold Museum’) which has many Inca gold artefacts in basement vaults. Then back to Linares, via the San Francisco cathedral, for the Witches Market, with stools offering llama foetuses (used to bring good luck to a new house constructon).


La Paz cityscapes

Central La Paz

Lama foetus in the Witches' Market, La Paz
Witches' market, La Paz
The evening was spent in Mongo’s in the south of the city, which became increasingly lively and funky as the evening drew on. Then on to a club for more drink, as if we hadn’t already had enough, some cheesy ‘Latino Rap’ (and even cheesier dancing), before a half decent Cuban band came on to perform some upbeat salsa. Late to bed…


Day 8 - 4 November

An early start, picked up by guide and driver for a privately organised climb in the mountains north east of the city. A two hour drive, the first hour through the sprawling suburb of El Alto, often on appalling roads, and then an hour on a very rough gravel track with the Cordillera Real appearing ahead of us – glaciated tops, many over 5,500m. We were heading for a lake known as Chiarcota, set amongst a group of 13 mountains known as the Condoriri, all between 5,100 and 5,700m. We walked from the Tuni dam, taking two hours to do a ‘three hour’ itinerary. It was a straightforward walk, mainly on gravel tracks and then on to llama paths, winding their way up the valley past other lakes and some very isolated farmsteads with llama and alpaca in abundance, ascending from 4,400 to 4,700 m.



Entering the Cordillera Real
As we neared our objective Chiarcota, the clouds closed in on the tops, seriously reducing visibility. After a quick lunch in a small barn (joined by a Tucan Adventure group) we set off down again for the two hour slog back to the car, occasionally rained on in increasing wind. I got a bout of 'tingly fingers' - my body's reaction to the first proper physical effort above 4,500m and similar to my expereience in Ecuador in 2004 - but it had subsided by the time we dropped below 4,500m again. Annoying! Views back to the Cordillera Real and forward to a distant view of Lake Titicaca.


Approach to Chiarcota, before the cloud came down!
Retuning to La Paz, we were rewarded with a great view of Illimani 6,439m looming above the city. We had a dinner at an ‘English Pub’ – curry , beer and great chips! All washed down with a pint of Tetley Tea! Early to bed…knackered.


Day 9 - 5 November

Departed La Paz at 0800, passing up through the chaotic streets of El Alto for the last time and out on to the altiplano once again in overcast weather. A two hour drive through barren country brought us to the ruins of Tiahuanaco. Here a guide with very poor English attempted to take us through the history of this amazing pre Inca civilisation which lasted for 2,700 years before failing around AD 1200, probably as a result of a prolonged drought. 





Tiahuanaco
Skull deformation, clever agriculture, advanced building techniques – a surprisingly gifted group of people who dominated the region for so many years. A tour of the museum, the ruins, with assorted ‘sun gates’, walled fortifications and pyramids, before a quick lunch and short drive to the border with Peru at Desquedero. Very straightforward border crossing, and then a long drive following the shoreline of Lake Titicaca to our right, witnessing an amazing hail storm as we progressed north. Distant views to Ilampu 6,480m on the other side of the lake and rounded, often terraced, mountains to our left.


Border between Bolivia and Peru, Desquedero
There were festivals in almost town we passed through and people here looked slightly wealthier than we had seen in Bolivia – more tractors, outside toilets next to most dwellings – and rich agricultural land adjoining the lake. Carrots in abundance! After another hour or so we stopped to view the Temple of Fertility where we guided by a couple of kids around a pre Inca construction containing both erect and inverted penises. Amusing for all.


Exodus group at the Temple of Fertility, en route to Puno
On to Puno, a town which has taxi rickshaws everywhere. We parked the truck in a compound and took a rickshaw to the Hotel Italia, set close to the attractive town centre, with throngs of people on the streets celebrating the final stages of the Jubilee Festival. We had a briefing by the guide on the forthcoming tour of Lake Titicaca then set out for a local restaurant…alpaca meat and some good red. Dodgy stomach overnight the result…


Puno




Day 10 - 6 November



Early walk into town with glorious blue skies all around. Off at 0800 by bicycle rickshaw to the harbour where we purchased gifts for our hosts at tonight’s home stay. Boarded a small motor boat for the 45 minute trip through the green algae caused by effluent pollution in the bay next to Puno (a treatment plant is being built which should resolve this) and out to the Uros floating islands. 


Leaving Puno for the Uros islands


On the floating Uros islands on Lake Titicaca
Stepping on to 2 m deep tortora reeds was a bit strange (in about 20m of water, apparently) and the locals (mostly a mixture of the Uros and the larger Aymara tribe) showed us how to make the islands, talked us through their life as reed dwellers, and ultimately persuaded us to buy their handicrafts. Entertaining enough and not too exploitative, but a bit too touristy for my taste. Then a short crossing from one island to another on a reed boat in order to visit a school where, rather embarrassingly, they sang for us. 


On Lake Titicaca
The rest of the morning passed as we travelled north across the lake for some two and a half hours to the island of Tarique. Glassy surface gave some great photo opportunities. Titicaca is the world’s largest high altitude body of water, fifteen times the size of Lac Geneva and 284m deep. Incidentally, the name Titicaca derives from the Aymara word titi (mountain cat) and the Quecha word caca, meaning rock – the cat inhabited the lake shores and was said to have visited the Sacred Rock on the Isla del Sol worshipped by pre Inca peoples. The link comes from the legend that the ancient indigenous people saw the eyes of the cat gleaming form the rock.
We landed in bright sunshine and ascended 100m on an easy path to the market square at 3,995m. The island’s inhabitants dress quite differently here, the men knit and wear Father Christmas like hats that they store coca leaves in. The women wear a black veil and red skirts. We enjoyed a good lunch of quinoa and vegetable soup, followed by lake trout, and then walked to the other end of the island where the boat had been repositioned to collect us for the short journey to our overnight stop, the island of Amantani.


On the island of Tarique, Lake Titicaca


Landing on Amantani, with clear views again to the distant Illanapu, we were split into couples and introduced to our family host for the night – Norma. A walk up through terraced fields led to a pleasant little farmhouse and cosy bedroom, later lit by candle. From the house at 3,881m we walked up to almost 4,000m to partake in the customary football match against the locals – exhausting, although I did manage to score a goal (at the right end!). The family daughters, Stefanie and Sabina then brought us back to the house in the gathering darkness. Waiting for dinner, a big electrical storm went off all around us…very dramatic. We enjoyed a simple dinner in the tiny (filthy) kitchen – vegetable soup with pasta, rice followed by traditional mint tea – with assorted family members drifting in and out. We skipped the planned entertainment back up in the village hall and enjoyed a good sleep in our cosy little room.


Amantani, Lake Titicaca, our island homestay

Homestay kitchen!
Day 11 - 7 November


Breakfast of pancakes and bread/jam, washed down with coca tea, then returned to the harbour to bid our hosts farewell. It took 3 ¼ hours on choppy waters to get back to Puno in light rain with heavily overcast skies. The algae on the approach to Puno had been dissipated by the overnight storm. Lunch and internet back in Puno before setting off again for an hours' drive to visit the Sillustani funery towers, 30km to the north. We visited the chullpas, very large white stone towers up to 10m in height in which the Colla tribe buried their dead. Set on a small peninsula this temple/cemetery consists of a ring of stones more than 500 years old. There are honeycomb chullpas, with superb stonework influenced by the advance of the Inca Empire, and the later more elaborate Inca-type stone masonry.


At Sillustani funery towers


It was an attractive setting overlooking lakes on all sides, with photogenic Peruvian country in the late afternoon light. A short walk back through the village brought us to our rough camp site for the night (rough=no toilets, showers and no running water). We quickly set up our tents and Anna and I repacked for my departure the following day. It started pouring with rain as dinner was being prepared and the meal was enjoyed inside the truck. Early to bed, but sleep disturbed by dodgy stomach and packs of dogs who barked all night…great.


Day 12 - 8 November


A long wait at Juliaca airport
Dropped off at Juliaca airport (outside the shabbiest town you’ve ever seen) and watched the truck disappear northwards towards Cusco. Got flight to Lima via Arequipa in the afternoon – great views of the El Misty volcano on the approach to Arequipa – and some big volcanoes seen en route to Lima. A fitting end to a short trip to South America. Lima overnight, back to UK the following day.


Volcano country north of Arequipa