Monthly archives of “May 2014

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Black Sea rainforest? Gorgeous, green, Georgistan

Rainforest in Georgia? (as in Georgistan, Black Sea, by the way, not as in ‘Good-Old-Boys’). I saw it marked on a Wikipedia map and it seemed like a damned good excuse to go and have a look-see….

Some background: The word ‘gorgeous’ is reputed to stem from Georgian women. Evidence I gathered supports this, from the passport control officer onwards. The origin of the word “Georgia” itself is a little less certain. Some say it comes from a local word for ‘wolf’, while others claim it has a much more prosaic ancient Greek origin, who labelledthe inhabitants as ‘farmers’ (same ‘geog’ as geography). My own two cents worth asks why, of all the people around them, would the ancient Greeks have singled out the Georgians as ‘farmers’? It’s one, and likely was then, one of the wildest, unruly places on the planet! The Greeks certainly came to the Georgian coast – they were all around the Black Sea. The legend of Jason and the Argonauts (unruly pirates themselves) and their search for the ‘golden fleece’ had its origins here. Persistent winds blowing off that same Black Sea means that western Georgia has one of the highest rainfalls in Europe. Well OK, there is some debate there – depending on your definition, Georgia is part of Europe, or at least a ‘gateway’ to Asia. I travelled to Georgia after arranging a personal guide/driver through Explore Georgia (highly recommended). I entered via Turkey and spent my first night in the coastal city of Batumi. Next day we headed up into the mountains where my guide had arranged a lift with a heavy truck taking some locals up to collect wood. Despite the usual weather, my day was cloudless (damn -it’s no good for photographing in the forest!). Our route was a deep, entrenched track, and our truck made a hard job of it. We wound up onto a ridge, eventually seeing the snowy Caucasus far in the distance. And finally it was ‘good’forest – heavily cut-over, utilised forest – but something more ‘natural’ would have been much harder to get to. For a brief visit it did just fine.

Our truck, and a very, very deeply entrenched track. Georgia.

Our truck, and a very, very deeply entrenched track.

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Starts and stops….

 

The view back over Batumi, Georgia.

The view back over Batumi.

Forest in Georgia.

Trees in the forest, Georgia

Trees.

Georgian forest with snow-covered Caucasus in the distance.

The snow-covered Caucasus in the distance.

Evergreen shrubs below the deciduous canopy of a Georgian forest. Rhodendron and holly.

Evergreen shrubs below the deciduous canopy. Rhodendron and holly.

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And Georgian girls.

 

But was it ‘rainforest’? One definition of temperate rainforest is that of Paul Alaback (1991), whose research has been based on North and South America. He suggested four factors to define a ‘temperate rainforest climatic zone’:

  1. greater than 1,400 mm annual precipitation, 10% or more occurring during the summer months
  2. cool frequently overcast summers, July (or austral January) isotherm < l6C
  3. fire infrequent, and not an important evolutionary factor
  4. dormant season caused by low temperatures, may be accompanied by transient snow

When Alaback (1991) applied this definition to the world – he found that four European areas were included: the northwest corners of Ireland and Scotland, the southern tip of Norway, and a small region of the Alps. A map of temperate rainforest in Wikipedia  claims to follow Alaback (1991) but uses a somewhat different definition:

  1. Annual precipitation over 140 cm (55 in)
  2. Mean annual temperature is between 4 and 12 °C (39 and 54 °F).

The Wikipedia map gives a slightly different distribution of ‘temperate rainforest’. For example, now all of Ireland is included, the north coast of Spain, the central Alps spot has moved south into the Balkans – but there is now a solid arc around the southeast Black Sea coast, including Georgia. Actually, in detail, either of these climatic definitions results in some parches of ‘rainforest’ in western Georgia. As long as definitions like these are seen for what they are – drawing attention to areas with a comparable climate: i.e very wet, ‘everwet’ and cool, then then I have no problem. But the forests in these areas cannot be distinguished from those lying just ‘outside’ (i.e., slightly drier or warmer). The line is artificial. Floristically they do not contain any of the evergreen Lauraceae family- which are distinctive elements of the ‘Laurisilva’ rainforest of the Canary Islands, or which are prominent components of fossil assemblages of rainforest in Europe. In fact, the Georgian ‘rainforests’ have no broad-leaved evergreen trees (there are evergreen pines), although there is an evergreen shrub layer and some evergreen vines (Filibeck et al. 2004). Fire seems to be more or less absent, certainly not a part of the ecology – so by some Australian criteria, that could make it a rainforest. Basically, take your pick. If it’s forest where it rains an awful lot – then yes, the Georgian forest is rainforest. But whatever the label, the forest is now a fragment of its former extent. It’s precious. If you ever get the chance, go there and show your support. Georgia is well-worth a look.

References

Alaback, P. B. 1991: Comparative ecology of temperate rainforests of the Americas along analogous climatic gradients. Revista Chilena de Historia Natural 64: 399-412.

Alaback, P. B. 1995: Biodiversity patterns in relation to climate: the coastal temperate rainforests of North America. In. Lawford, R., Alaback, P. and Fuentes, E. R.  (Ed.)  High latitude rain forests and associated ecosystems of the west coast of the Americas: Climate, hydrology, ecology and conservation. Ecological Studies Vol. 116. Biodiversity patterns in relation to climate: the coastal temperate rainforests of North America., Springer-Verlag: 105-133.

Alaback, P. B. 1996: Biodiversity patterns in relation to climate- the coastal temperate rainforests of North America. In. Lawford, R. G., Alaback, P. B. and Fuentes, E.  (Ed.)  High-latitude rainforests and associated ecosystems of the west coast of the Americas. Biodiversity patterns in relation to climate- the coastal temperate rainforests of North America, Springer: 105-133.

Filibeck, G., Arrigoni, V., & Blasi, C. 2004. Some phytogeographical remarks on the forest vegetation of Colchis (Western Georgia). Webbia: Journal of Plant Taxonomy and Geography, 59, 189-214.

Veblen, T. & Alaback, P. B. 1996: A comparative review of forest dynamics and disturbance in the Temperate Rainforests of North and South America. In. Lawford, R. G., Alaback, P. B. and Fuentes, E.  (Ed.)  High-Latitude rainforests and associated ecosystems of the West Coast of the Americas. A comparative review of forest dynamics and disturbance in the Temperate Rainforests of North and South America, Springer: 173-213.

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Canary Islands – ‘Last’ Rainforest in Europe (?)

The fossils are clear – just a few million years ago Europe was covered in broad-leaved, evergreen forest. There were palm trees and numerous other trees that are now only found in the tropics. Under almost any definition, this would be called ‘rainforest’. The climate then cooled and dried and the evergreen forests were mostly replaced by deciduous ones. Europe has plenty of evergreen pines now, but evergreen broad-leaves are few (holly is one). On these criteria, the rainforest has vanished. However, there is a place that is sometimes advertised as ‘The last rainforest in Europe’ – high in the mountains of one of the Canary Islands. The Canary Islands lie a little to the west of the African coast. They sit adjacent Morocco and Western Sahara, so it’s a bit of stretch to include them in Europe. This claim may have more to do with travel agents than geographers. That they have rainforest is less questionable.

Map of the Canary Islands - just off the west coast of Africa.

The Canary Islands – just off the west coast of Africa.

I can generally trace many of my stuff-ups back to the precise moment where I made an Assumption. There was some point, generally early on in what ever happened, that my brain unquestionably took me down a certain path. For the Canary Islands, it was flicking through a Merian journal in Frankfurt airport. The journal happened to be written in German, but the photographs of ‘The last rainforest in Europe’, were stunning. I resolved there and then to go there and took a casual mental note of a couple of place names. These were, I assumed, enough to get me going to the island of La Gomera, where the best rainforest remains.

In Madrid I popped into a travel agent and asked for tickets to La Palma. Or something like that. In retrospect the agent may have tried to clarify something with me, but with a language barrier, I probably just nodded dumbly and said ‘fly me’. I had been in the Canary Islands for a few days before I found out that I was in Las Palmas, not La Palma. Ironically this was by sharing a bunk room with a Spanish school teacher, with German as our only common language. The city of Las Palmas is on the island of Gran Canaria, to the east of La Gomera. The island of La Palma is to its west. Just to add to the mix, the main city of the island of Tenerife, is Santa Cruz, while the main city of La Palma, is … Santa Cruz. As it turned out, I was about as far away from La Gomera as I could possibly be. The location of the Canary Islands is not one where the word ‘rainforest’ springs to mind. They are a group of volcanic peaks, sitting just west of the Sahara – and the environsof Las Palmas emphasises this. The Canary Islands are mostly known as haven for sun-seeking tourists. Plant cover is practically absent, though the ‘Canary Island Palm’, now spread throughout the world’s cities and presumably the culprit behind my fiasco with names, seemed to thrive almost anywhere. Unfortunately, with the virtual lack of greenery and dry climate, rubbish just remained in full view wherever it was dumped or had blown. The locals seemed rather indifferent, no doubt over-dosed on tourists, though helpful in a matter of fact way when I asked for local directions.

One side of the Canary Islands - sun, sand and tourists.

One side of the Canary Islands – sun, sand and tourists.

Typical lowland vegetation of the Canary Islands - semi arid and with palm trees.

Typical lowland vegetation of the Canary Islands – semi arid and with palm trees.

Having finally oriented myself, I took two ferries – one to Tenerife, then another to La Gomera. In the town of San Sebastian I got a room in the house of a little old lady, and the next day got a bus into Garajonay National Park, in the highlands. I learned there was a single bus back to the town at about 5 pm and I had to wait at a certain roundabout.

San Sebastian, Canary Islands - looking up towards the clouds, hiding the rainforest.

San Sebastian – looking up towards the clouds, hiding the rainforest.

Barren, dissected country, on the winding road from San Sebastian to the National Park.

Barren, dissected country, on the winding road from San Sebastian to the National Park.

Finally, I was in the ‘last European rainforest’. It’s what the Spanish call the ‘Laurasilva’. The situation of having dry vegetation in the lowlands and moist uplands with rain, or ‘cloud forest’ is frequently found around the world. While I was there, the forest was in perpetual cloud or mist. Cloud drip, rather than actual rain (La Gomera has a pronounced rainfall dry-season each year), is a key factor in keeping the area wet, mossy, and looking like a rainforest.

I wander along a misty path in the rainforest. La Gomera, Canary Islands

I wander along a misty path in the rainforest.

Under the canopy - low, small trees, but it's cool, wet and moss-covered. Canary Islands

Under the canopy – low, small trees, but it’s cool, wet and moss-covered.

I went for a relaxing walk along a path, beneath the canopy of moss-laden forest. The trees are not large and the biodiversity is low – there are some heath trees and just four species of the evergreen laurel family. It’s the presence of these laurels that really get botanists excited. Laurels were common and diverse in the original European rainforest, as they are in many warm rainforests today. Even if the Canary Islands are not Europe, they are still the nearest place with a forest that includes laurels. So not only does the forest have the ‘look’ of a rainforest – it fits some floristic criteria too.

A schematic cross-section of a Canary Island. The laurel-dominated rainforest is a wedge between the semiarid country below and the pine forest above.

A schematic cross-section of a Canary Island. The laurel-dominated rainforest is a wedge between the semiarid country below and the pine forest above.

Despite the low biodiversity, this tiny spot is a refuge from what was once wall-to wall across Europe (well before humans arrived on the scene). With the exception of a young couple with a small child, I had the place to myself, and there was plenty of time to explore and then wander back to the roundabout in time for the bus.

As the rainforest lay in a pass, I could walk evenhigher – and this is where things got surprising. I’m used to the wet forest forming the highest forest on a mountain – anything higher is typically shrubland, where trees are limited by cooler temperatures. But here – the cloud-shrouded wet forest passed upwards into sunny, dry pine forests. The reason for this is that the clouds all form where trade winds from the sea blew through the narrow pass by lower down. Higher than that they did not form – but the temperature was plenty warm-enough for trees. I was happy to have learnt something new and wandered back down to the still cloud-enveloped pass and waited at the roundabout for the bus. Cloud below pine forest, Canary Islands.Cloud below pine forest, Canary Islands.

When the bus came, it shot past so quickly and without any hint of even slowing that I started to doubt I saw it at all. But it had, and the only option now was to start walking – the 17 km back to San Sebastian. I tried hitching but the car drivers seemed as indifferent as whoever had been driving the bus. Eventually it was dark and any chances of hitching had likely evaporated and I gave up.  It was pitch black except for the lights of San Sebastian far below. As the hours passed and I plodded on down the hair-pin bends, by some curious optical illusion, the lights of the town rose, like some galaxy, until they appeared to be above me. Then a car pulled over, unbidden. The driver, who spoke just enough English to bellow “Hah, others think you are Bandido – but not me!” That was all he ever said, and he dropped me in San Sebastian without a further comment or wave.

All that was left of the day was to negotiate with the little old lady to let me in at 0100, and finally get some sleep.

Reference

Juan, C., Emerson, B. C., Oromí, P. & Hewitt, G. M. (2000). Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands. Tree 15, 104-109.

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The Last Deep Dark Primeval Forest in Europe?

In Poland there are any number of subjects that might make good postcards, Polish girls perhaps. But decaying logs?  In the far east of Poland, this is in fact the case. Białowieża Forest is reputed to be the last, or perhaps the last sizeable ‘untouched’ forest in Europe. Unlike the rest of Europe, where forests are managed to within an inch of their lives, where dead-wood is immediately whisked away or trees cut well before they become dead-wood, a place where trees are allowed to grow old, fall, and rot, is a novelty. So novel that botanists practically burst into tears at the sight, and enterprising locals, aware of this, take photographs of fallen trees and put them on postcards.

A decaying log in Białowieża Forest. This natural process is a rarity in Europe.

A decaying log in Białowieża Forest. This natural process is a rarity in Europe.

Light shines in a tree-fall gap in Białowieża Forest. Beyond - the dark under a closed canopy.

Light shines in a tree-fall gap in Białowieża Forest. Beyond – the dark under a closed canopy.

Białowieża Forest is certainly deep and dark. While I was staying at the local Youth Hostel I was joined by a class-load  of Hungarian students. One of their number had left the bus at one of the brief stops, wandered into the forest – and emerged, somewhat shaken, about five hours later. I nearly did the same thing, while wandering the forest tracks toward dusk. I had come across the Polish-Belorus border – a slightly overgrown cut-strip with the remains of a security gate in the undergrowth. The smart-arse thing to do would have been to sneak across, just to say I’d ‘been in Belorus’. But I had no idea what hidden eyes may have been watching me. I was in enough trouble as it was, with trees towering above me in all directions, no clues as to directions, and it was getting dark. Fortunately I chose the correct fork in the path.

Ever since then I’ve mused about what it would have been like to have walked from there to the west, say 7,000 years ago. This was pre-agriculture for this region with the locals hunting, gathering and fishing. Such a walk, so it has long been said, would have been hundreds of kilometres under the canopy of a deep dark forest – broken only by the larger rivers and perhaps some swamps. Or was it? A few years ago a detailed thesis by Frans Vera made a full-frontal assault on this belief, attempting to turn it on its head. Instead of vast tracks of deep dark forest, Vera argued it was mostly an open park-like vegetation. The details of Vera’s hypotheses – and the explosion of responses to it, would make the basis of many posts, but part of Vera’s arguments were specifically based on Białowieża.

Vera pointed to research that plants such as some oaks and hazel – which pollen evidence shows have been part of Białowieża for thousands of years, are no longer regenerating. That is, there is no sign that their seeds are establishing. Vera made the connection between the break down of this process- and the loss of large herbivores in the forest. Until very recently, large herbivores were an integral part of the forest – animals like the extinct auroch, and then cattle. It was only when cattle were excluded that the structure and composition of the forest began to change. Vera argued that large herbivores were needed to maintain a partially open environment with patches of ‘thorny scrub’ that were the only places some tree species could successfully regenerate in.

There is plenty of opposition to Vera’s broader hypothesis, but it seems like the current appearance of Białowieża Forest is unlikely to be ‘primeval’. Rather, as one researcher, Andrzej Bobiec, put it, it is “culturally modified ancient forest”. In the sense that it has been left to run-wild, with natural processes like tree-fall and decay to take place – Białowieża could be seen as an example of ‘rewilding’. However, this would be to miss the point that by excluding large animals, humans have, oxymoronically, placed limits on wilding. It may be re-wilding, but it’s not a re-turn to the past.

It’s somewhat sad to realise that even this place is not untouched, but we are thankful it exists at all. Białowieża is deep and dark and wild – enough that you can quickly get lost or disoriented. In the deep-down yearning in some of us for the ‘primeval’, perhaps that is what really counts. It’s a place deep dark and wild enough that you can still believe a forest path will lead you to a rusalki sitting on a decaying log. Now there’s a postcard.

References

Bobiec, A. 2012. Białowieza Primeval Forest as a remnant of culturally modified ancient forest. Eur J Forest Res. 131:1269–1285.

Vera, F. 2000. Grazing Ecology and Forest History. CABI Publishing, 506 pages.

 

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Discovering the ‘Bridge of Stone’ – the ancient route over the Kawarau River, New Zealand

Map showing location of 'Chalmers Leap' (the stone bridge) over the Kawarau River, Central Otago.

Kawarau map

Part way along the Kawarau River between Cromwell and Queenstown (Central Otago, New Zealand) is a feature known to Maori as ‘Whatatorere’ (Kaumatua Huata Holmes of Kati Huirapa Runaka ki Puketeraki pers. comm. to Lloyd Carpenter, lecturer in Maori Studies at Lincoln University) and to Pakeha (non-indigenous New Zealanders) as the “Natural Bridge” or “Chalmers’ Leap”.

Before bridges were built, it was the only spot along the Kawarau River where travellers could cross the wild river without a boat, or risking their lives trying to swim. The river narrows right down, so that one can either walk, or jump, from one side to the other. The Maori knew all about it. That the bridge was found is testament to how well the Polynesians explored New Zealand. It was a geological miracle that it existed at all, let alone be in virtually the ideal place at the end of the natural trail down the Cardrona Valley, Roaring Meg Stream, and then up the ridge of Mt Difficulty for a relatively easy walk on into Southland.  It is highly likely that the crossing was used for more than 600 years.

The first Polynesians would have approached the ‘bridge’ through beech (Nothofagus) forest. The dozen or so beech trees a few kilometres up the Roaring Meg are the last remains of the forest that grew over the southern Pisa Range, and no-doubt extended up Mt Difficulty as well. But this was quickly burnt-off, and the area became a rocky tussock and shrub-land. Generations of Maori would have made their way down through the scrub along what probably became a well-worn trail. Perhaps they rested by the river a while, and then continued on their way.

It would have been used by Te Puoho’s war party as it moved from Wanaka to Southland in 1836. The first European explorer in the area, Nathanael Chalmers was lead over the crossing by the Maori guide Reko in 1853. Reko said it would be a ‘bridge of stone’. There was evidently some element of risk in the crossing at the time – as the European name became “Chalmers Leap”.

The view down the Roaring Meg Ck, with its valley framing Mt Difficulty in the background.

The view down the Roaring Meg Ck, with its valley framing Mt Difficulty in the background.

One of two small Hoheria lyallii on the edge of the Roaring Meg. Relict Nothofagus in the background.

One of two small Hoheria lyallii on the edge of the Roaring Meg. Relict Nothofagus in the background.

After Chalmers a flood of Europeans came, and, perhaps predictably, some fool blew it up looking for gold (I recall reading this somewhere, but haven’t relocated the reference). As a relative local, I had been brought up to understand that the “Natural Bridge” had gone, but a few years ago I was thrilled to find that this isn’t quite the case. You can, in fact, walk across a rock from the Nevis side (no ‘leap’ involved) – and stand on a rock with the whole Kawarau raging below you. I opted not to try and get up the other side – it’s now a sheer rock wall. However, I’ve since found out that it is possible to work your way up a ‘gut’ in the rock face, but also that the crossing is only possible when the river is markedly low.

The view down to the Natural Bridge from the Mt Difficulty (southern) side.

The view down to the Natural Bridge from the Mt Difficulty (southern) side.

Standing on a rock with the whole Kawarau River roaring underneath!

Standing on a rock with the whole Kawarau River roaring underneath!

That this incredibly ancient and historical focal-point is barely-known, let alone no-longer used (or practically usable), is a tragedy. New Zealand is making leaps and bounds in creating and advertising long-distance walk/cycle-ways. For example, the track from the Cadrona and down the Roaring Meg is a public right of way, but when it reaches the Kawarau – all you have to look forward to is risking your life with the traffic along the periodically narrow road to Cromwell or Queenstown.

What could be done? At Chalmer’s Leap some sort of ladder/bridge arrangement would be needed to rebirth the ancient crossing (argh- safety, liability!!!). Or perhaps the nearby cableway could be modified, or a trail could connect with the bridge at the goldmining/Wild Earth winery. But once on the south side of the Kawarau – there is no longer any right of way over the mountains and down to Southland. “Stuff’ is certainly happening in the area. There is currently a huge operation to clear the ‘wilding pines’ (in this case, Douglas Fir). Hopefully some effort will be made to  replace them with some native trees. There has been some native planting along the roadside near the Roaring Meg car park, mostly kowhai and ‘mingimingi’, and towards Cromwell, what looks like an older one, including flax, toi toi, mingimingi and even a couple of Pittosporum.

References For the story of Nathanael Chalmers and Reko, see: Temple, P. 1985. New Zealand Explorers. Great journeys of Discovery. Whitcoulls, Christchurch.

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Mongolia – The Lost Forests of the Gobi

I grew-up in a semi-arid, naturally treeless part of the world – Central Otago, New Zealand. Well, actually not quite. There are tantalising scraps here and there that hint that the mountains and valleys were once forested. These include tiny relicts of the former vegetation, usually in the most fire-protected spots of the most areas (read: steep/rocky). When I worked in the Gobi Altai in Mongolia (the mountains to the north of the Gobi Desert) I was intrigued with the similarities to home. It’s the same kind of landscape, the same colours, sometimes the same sky – but on a vastly larger scale. It’s Central Otago ten or a hundred times bigger. Like Central, it’s virtually treeless. But now and again there is a little green, a patch of forest surviving in a remote gorge, or almost incredibly isolated trees in the arid lowlands. After weeks at a time of not seeing plants higher than me, trees were always worth a look and some photos. This is a brief introduction to some of what I’ve seen.

A lone larch tree on a ridge in the Gobi Altai mountains, Mongolia.

A lone larch tree on a ridge in the Gobi Altai mountains.

Another isolated larch tree, high up a valley of the Gobi Altai, Mongolia.

Another isolated larch tree, high up a valley.

In the mountains the trees are always larch – a deciduous conifer, green only in the brief Mongolian summer.

One of the small forests still remaining in the Gobi Altai. For several weeks my camp was in the distant foothills.

One of the small forests still remaining in the Gobi Altai. For several weeks my camp was in the distant foothills.

Inside the remaining larch forests of the Gobi Altai, Mongolia - a welcome change from the bare rock.. My field partner, Nyambayar for scale.

Inside the remaining larch forests – a welcome change from the bare rock.

Not far from the track a few kilometres from one of our main camps – was this ridiculously small patch of willows. It is the only patch of trees for a huge distance around. The special place was recognised by someone, years ago, who made the effort to fence it off and protect it from the goats. Alas, the fence needs a little attention.

A minute patch of stunted willows in a valley on the edge of the Gobi Altai, Mongolia - the only trees for tens of kilometres around one of our camps.

A minute patch of stunted willows – the only trees for tens of kilometres around one of our camps.

Highly coppiced willow trees inside the patch - and a fence - the remains of someone's attempt to preserve the trees. Mongolia.

The highly coppiced trees inside the patch – and a fence – the remains of someone’s attempt to preserve the trees.

Some of the larger rivers have a few patches of trees along them. At the edge of the mountains these may be larch, but willow is more typical in the open country.

Between a rock and a hard place - larch trees on the edge of a dry river bed.. Gobi Altai. Mongolia.

Between a rock and a hard place – larch trees on the edge of a dry river bed.

A nice patch of willow along the river edge by the town of Bajanhongor, Mongolia.

A nice patch of willow along the river edge by the town of Bajanhongor.

Now and then you come across amazingly isolated trees, in the middle of what you thought was pure desert. The Mongolians recognise these as ‘ganzmut'(single-tree) and they are often revered as special by Buddhists. Some of these are elms.

A single tree in the middle of the desert, Mongolia. The blue material wrapped around it indicates it is a special tree for Buddhists.

A single tree in the middle of no-where. The blue material indicates it is a special tree for Buddhists.

The last tree. From here on south - the Gobi Desert proper.

The last tree. From here on south – the Gobi Desert proper.

These remaining trees speak of what was – but importantly, what could be. The fact of their existence, however tenacious, shows that they can grow in this incredibly harsh environment. At one stage the Gobi Altai were probably covered in larch forests, and there were probably large patches of broad-leaved forest in the lowlands. All sorts of things would change with reafforestation – slow run-off would mean that rivers that now only flash-flood may flow throughout the summer, the forests themselves may have an ameliorating effect on the climate, and there could be a sustainable supply of wood for building and fuel.

It would take some special people with a bit of vision. Fortunately there are a few, and I’ll mention them in a later post.

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Grumbling about Graywacke

When I was growing up in Central Otago (New Zealand) graywacke was a bane of my life, and certainly of my Dad’s too. The family lived on a section near the foot of an alluvial terrace dating back to glacial times. The loess soil was soft, but the impact of a metal fork on a graywacke boulder, hidden in the otherwise nice soil, jared up your arms and left a metallic streak of the fork tongs on the rock surface.

A humble cobble of greywacke, picked up on <a title="Mondillo Vinyards" href="http://www.mondillo.com/">Mondillo Vinyards, </a>Bendigo, Central Otago.

A humble cobble of greywacke, picked up on Mondillo Vinyards, Bendigo, Central Otago.

Graywacke was simply a word I was brought up with – graywacke boulders are a common feature of the Quaternary alluvial terraces of Central Otago, and I could spot them from an early age. To me, they were simply hard, drab, and dead-boring (no fossils). At the time I was oblivious that graywacke was the bane of other people too, although for quite different reasons than its effect on digging up potatoes. The issue was over the definition and correct usage of the term amongst professional geologists. It mostly stayed below my radar, but it’s time now to try and understand what the problem was.

It became clear in the early 1960s, that the term “graywacke” meant rather different things to different people. Essentially it is a sedimentary rock composed of sand and mud. But some workers liked to emphasise its sorting (poor), others its immaturity (the grains included many feldspar and lithic fragments), or that the grains were angular. But there was also a tendency to link it to an origin. For example this could be in terms of the environment of deposition – graywacke is a typical rock of sequences that are called ‘flysch” , which in turn were conceptualised as part of ‘geosynclines’, and formed in deep-water. Or it could be lined to the actual process of deposition – beds of graywacke often show grading base to top.  Also, which may or may not have complicated matters, some worers lied to refer back to the original ‘type’ locality for graywackes in Germany.

There were calls for the use of ‘graywacke’ to be discontinued, or at least for a definition to be agreed upon. Robert Folk, the guru of sandstone, began using the term ‘phyllarenite’ in 1966.  This was a term, precisely defined by the relative amounts of Quartz, Feldspar and Lithics amongst the sand fraction. He felt that in a purely descriptive terminology, notions of origin, either of location or process, have no place, and because of the lingering link of ‘graywacke’ with origins, it was best to do away with it completely. In his classic text on sandstone petrology (various editions: 1968, 1974, 1980),  announced he would abandon graywacke, except as a broad field term. In a 1970 paper, which was specifically about classifying rocks in New Zealand – a place that could otherwise be known as the ‘Land of Graywacke’, the term is not used at all.

But whether you call them ‘phyllarenites’ or ‘graywackes’, the distinct link with a geosynclinal and/or deepwater origin doesnt go away. It was some years later before the explanation became clear. Phyllarenites’ or ‘graywackes’ – essentially poorly-sorted, immature sandstones, are a common product of turbidity flows, which are a typical feature of deep-water environments along continental shelves flanking active landscapes. New Zealand, which owes its existence to straddling a plate-boundary, is a very active place – and consequently a hodge-podge of rocks, many formed in a deep-water setting. It’s that continuing geological activity that gets those graywacke …. I mean phyllarentite …  cobbles into the potato-patch.

References pertaining to ‘graywacke’

Boswell, P. G. H. 1960: The term graywacke. Journal of Sedimentary Petrology 30: 154-157.

Dott  Jr., R. H. 1964. Wacke, graywacke and matrix–what approach to immature sandstone classification? Journal of Sedimentary Petrology 34: 625-632.

Folk, R. L. 1954: The distinction between grain size and mineral composition in sedimentary-rock nomenclature. Journal of Geology 62: 344–359.

Folk, R. L. 1968, 1974, 1980: Petrology of Sedimentary Rocks. Austin, Texas, Hemphill.

Folk, R. L. 1966: A review of grain-size parameters. Sedimentology 6: 73–93.

Folk, R. L., Andrews, P. B. & Lewis, D. W. 1970: Detrital sedimentary rock classification and nomenclature for use in New Zealand. New Zealand Journal of Geology and Geophysics 13: 937-968.

Folk, R.L., Ferm, J.C., 1966. A portrait of Paul D. Krynine. J. Sediment. Petrol. 36, 851 – 863

Huckenholz, H. G. 1963: Mineral composition and texture in graywackes from the Harz Mountains (Germany) and in arkoses from the Auvergne (France). Journal of Sedimentary Petrology 33: 914-918.