GUATEMALA....LAND OF VOLCANOES

If you are young and fit and want to climb a volcano, then go to Guatemala, its got dozens of them, mostly in the height range of 3500 to 4000 metres., so you'll get a good view from the top. Also, Guatemala is a great country to travel in once you get used to and learn to enjoy the Indian culture and cuisine.  Some backpackers seem to have moved in for good at villages around Lago Atitlan, located in the Western Highlands, which is a popular tourist region.

Plate Tectonics in action

Guatemala lies on the Pacific  "Rim of Fire"  which is important in explaining the concentration of volcanoes around the rim of the Pacific Ocean.  The geological theory of "Plate Tectonics" was founded as recently as 1960, and explains how mountains are built and volcanoes are born.  The continents are considered to be rigid plates (the SIAL, or a silicious scum) which move around by plastic flow on top of the earth's mantle, which has a denser composition (the SIMA).  Movement rate is about 10 cm per year, so in a million years a continent could move a 100 kms. 

Along the eastern side of the Pacific Ocean, following Central and South America, there is an elongated 'Subduction Zone" whereby the continental crust of Central and South America is thrust over the Oceanic crust, causing earthquakes and melting of the newly buried material. This magma is squeezed upwards and forms volcanoes at the surface, maybe one volcano every 50 kms along the mountain chain of the Andes and in Central America.

Wikipedia lists 29 volcanoes for Guatemala all lying in the SW Highland region close to the Pacific Ocean and having elevations of 1200 to 4200 metres.  Two are recorded as being active, Pacaya and Fuego, the later's eruptions causing much damage and casualties at present (May 2018). The Pacaya volcano (2552 metres)  is a favorite one for backpackers to climb via organized tours from the tourist city of Antigua (the old capital). I tried this out but was defeated by gale force winds on nearing the summit.  It was impossible to stand up.  The only way up was to crawl on the steep ash slope.  Not good.....so we retreated down to shelter in the forest, and so back down the track to the parking lot where our bus awaited.

The volcanoes make for lovely photographic backgrounds to the tourist regions centered by the towns

Lago Atitlan, with Volcanoes Toliman 3158 m, and  Atitlan 3537 m,
 in the background.

Antigua, and Panajachel on Lago Atitlan. Some volcanoes often give a puff of smoke, just to remind us that the fires below are still smoldering.  Antigua, population now about 30,000, the original capital of Guatemala, was founded by the Spaniards in 1542.  It was so continuously devastated by earthquakes and volcanic eruptions that the capital was moved in 1775 to what was considered to be a "safer" region"  called "Guatemala City" having now about 2 million inhabitants.

Antigua remains a beautiful tourist town whose skyline is dominated by a trio of volcanoes having sinister reputations.....they appear on the city's coat of arms.  Volcan Agua lies to the SE, Fuego is SW, and Acatenango is to the west, all about 3700 metres high.  Volcan Agua is about a 5 hour climb to the top.  Fuego is out of bounds as it is erupting at present.

Lago Atitlan is a caldera lake of volcanic origin.  It measures about 10 km across and 25 km wide.  It was formed about 1.8 million years ago when a super-duper volcanic explosion took place that blasted a hole in the region, which subsequently filled up with water. It is estimated that about 300 cubic kms of material, mainly tephra, was ejected and covered the region as far away as Florida and Ecuador.  At a later date new volcanoes sprouted up around the rim of the caldera which are the ones we see today.  The super eruption that formed the crater lake is known as the Los Chocoyas eruption, being named after a bird that makes its nest in the soft ash.

Lago Atitlan is a major tourist attraction of the Western Highlands.  The small villages found around the lake shore are accessed by boat from Panajachel, the main town on its shore.   The village of San Pedro, across the lake at the foot of Volcan San Pedro, is a very popular place for tourists and backpackers, for experiencing the local cuisine and also for attending Spanish language schools.  Growing and processing coffee is a local industry.  The lake was stocked with black bass in 1958.  I did see one caught  from the shore, of about 3 lbs, on a spinner.  I had no luck.  Lago Atitlan is a place where you could happily disappear for ever.   Many backpackers are doing just that.
Regards from Allano

Yes, I'll buy that.

No thanks, I don't want to buy a chook.

ON FOSSIL BEACHES

Rocks have lots to tell us if you speak their language.  You have to be a geologist to have a rapport with rocks, minerals, and gemstones.  Fossil shells are fairly common place and make for interesting initial collections for hikers exploring the outdoors.    But a fossil beach?  I have found some amazing ones in my travels.

A fossil beach denotes shallow water, such as found in a sea water estuarine system.  A current or tidal flow may create ripple marks over extensive areas of flat beach.  These ripple marks can be preserved when covered over by later deposits of sand and mud.  This can happen with terrestial flooding from rivers, or from regional subsidence.  It happens frequently.   The amber deposits of Guatemala are found in such sedimentary rocks of estuarine origin.

Jo standing by a fossil beach in the Adelaide Hills

But what about close to home where I live?  In the Adelaide Hills, between the suburbs of Belair and Mitcham there is a quartzite quarry with a wonderful exposure of ripple marks. It's on the steeply dipping side of the quarry wall of fine sandstone of the Kanmantoo basement rocks, and is about 400 millions old.

It is a nice afternoon scramble down hill northwards down the gully and so to Mitcham metro station.  Take the train both ways. Enjoy the city views, take a lunch. Watch out for the local wild life, the koalas, the foxes, and on hot days beware of brown snakes slinking around in the shrubbery.

The most spectacular fossil beach I have encountered is rather difficult to get to.  It forms the exposed crest of the Spero Range inland from Bathurst Harbour in South West Tasmania. It is composed of flat lying glaringly white quartzites of Pre-Cambrian Age, and looks like a ripple marked sandy beach formed just yesterday.  It invites you to strip off and dive into the water, but the tide went out maybe 800 million years ago (see Tasmanian Mines Dept Ref. below).

Dinosaur footprints in Bolivia…..being inspected by  Philippa Haselgrove,  from Adelaide.  (click to enlarge image)

Sometimes creatures have walked along these ancient beaches and have left their footprints.   Not human beings of course, for it was before their time.   Go back a 100 million years or so and you may encounter evidence of dinosaurs out for a stroll along the beach, leaving footprints of Mum or Dad and the youngsters in the sand, and the dragging furrow of their long tail.   A good example of this is in Bolivia, at a cement works quarry near Sucre. Take at taxi out to see the sights.  The steeply dipping mudstone of the quarry wall  is covered in dinosaur footprints, both large and small, made by Tyrrannosaurus rex , having feet up to 80 cm across,  and of a smaller iguanodon.    

So the rocks do speak to us and have a lot to say about how they were formed.  You may find rocks with fossil shells on the Adelaide beaches and elsewhere, which make nice ornamental pieces for display at home.  They will remind you that all the present political skulduggery is just a flash in geological time, so don't worry too much about it.    Regards from Allano.

An Adelaide sandy beach at Brighton....no dinosaurs here.

SW Tasmanian geology and Spero Range ripplemarks.
http://www.mrt.tas.gov.au/mrtdoc/dominfo/download/TR4_34_46/TR4_34_46.pdf

Old  quarry in Adelaide Hills showing ripple marks.

Foto opposite: Having a picnic with Joanna, Christobel and dog Jarrah in the old quarry showing ripple marks on the sloping walls.   The track down from the road above is rather steep so be careful.  The area is well signposted giving the history of the workings.  It's a nice outing on a summer's day.

Regards from Allano









PS: I have found some more dinosaur footprints.   These ones are preserved for tourists to look at near Mendoza in Argentina.   (Click to enlarge images)