Miocene leaf fossil from Blue Lake, St Bathans, New Zealand
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Blue Lake, St Bathans – the most biodiverse Miocene fossil plant locality

The biodiversity of Blue Lake, at St Bathans, New Zealand, is precisely zero. It is an artificial lake partly filling a hole blasted out in the search for gold in the 19th century. The hole is directly in front of one of St Bathan’s and New Zealand’s gems – the Vulcan Hotel. If you ran out the front door and forgot to stop at the cliff marking the edge of the old workings – you would land in one of the most biodiverse fossil plant sites anywhere on the planet.

Blue Lake, St Bathans, New Zealand

Blue Lake, St Bathans, New Zealand

The gold miners were sluicing quartz-rich gravel and sands. But in among those are thinner beds and lenses of mud. These are often full of plant fossils of Miocene age – say around 17-18 million years. Sometimes these are amazingly-preserved whole leaves – the featured image and one below show fossil leaves that have been floated out of the mudstone and then set in glycerine jelly between sheets of plastic. But often the fossils are just a hash of leaf fragments. This looks like a handful of compost at first, but it’s this hash, plus the extremely good preservation of that hash – that can make just a single handful of mud rich with fossils.

On the slope marking the edge of the Blue Lake digging and in front of the Vulcan Hotel there used to be a pine tree. It was my marker to locate a lens of mud remarkable by itself for its fossil plant content. In a few handfuls of mud from that lens were seven genera of conifers and at least 48 flowering plants. The conifers included some of our familiar New Zealand trees – like matai (Prumnopitys) and rimu (Dacrydium). But there were also surprises. There was Acmopyle – unique as a ‘hairy’-leaved conifer, and only growing in Fiji and New Caledonia now. Also Retrophyllum, a conifer with a distinctive paired arrangement of leaves along its shoot, but now found only in New Caledonia, Melanesia and South America.

Miocene leaf fossil from Blue Lake, St Bathans, New Zealand

Miocene leaf fossil from Blue Lake, St Bathans, New Zealand

And that little lens was just the start of it. Blue Lake has many such lenses, and over the hill is a ‘sister-lake’ – one of the local names being ‘Grey Lake’. It has a similar kind of geology. The sands and mud exposed in these lakes were deposited in an ancient river flowing along what geologist Barry Douglas (1986)  has called the ‘St Bathans PaleoValley’. It came from uplands in the west, to the coast somewhere to the east. In both Blue and Grey Lake muds I’ve now recorded a total of 13 conifers, 144 flowering-plant types and a further two cycad-like ones. To put this biodiversity in context, As a comparison, today there are around 215 species of tree in the entire New Zealand region (including the subtropical Kermadec Island; McGlone et al., 2010) and nine genera of conifers. So in an area of just a few hectares – there are more fossil conifer types than in all of New Zealand today. This is one of the most biodiverse, and perhaps the most, Miocene plant fossil localities anywhere.

What caused this high biodiversity? It was certainly warmer – the climate was warm temperate or even subtropical. Average temperatures would have been at least 6-7 degrees warmer than today. But perhaps more importantly, the cooler temperatures would have been much warmer. The harsh frosts and snow that St Bathans gets now, would have been entirely unknown. The kinds of rainforest plant fossils found at Blue Lake prove that rainfall too, would have been higher and more consistent, quite unlike the low and drought-ridden climate that the area has now. On top of that, Douglas considered that the ancient river was ‘braided’. This is a type of river that has many channels, and switches between  them from time to time. This process keeps vegetation in various stages of ‘succession’, allowing many species a chance to find their niche.

Vulcan Hotel, St Bathans, New Zealand

Vulcan Hotel, St Bathans, New Zealand in the snow. There would have been no snow, or even frosts, during the Miocene when biodiverse rainforest grew here.

The Miocene plant fossils of Blue and Grey Lakes are a treasure -trove and much remains yet to be understood. Many of the fragmentary plant fossils are still unidentified. They are clearly not plants living in New Zealand today – but where will similar plants turn-up? New Caledonia? Patagonia? Madagascar? And just what were the plant communities that lived in the St Bathans Paleovalley? How many new fossils wait to be found?

And that first lens of mud? The one beside the pine tree? Pine trees are an introduced, often invasive conifer in New Zealand. Their spread across parts of New Zealand is causing problems (they shade out smaller natives, acidify the soil and are a fire hazard) and so the Department of Conservation is doing their best to control the pines. That pine, one of the few trees in an otherwise naturally vegetation-free spot, was removed, and along with it, much of that biodiverse fossil lens. In fact, with the pine tree gone and the disturbance that created, I’ve had trouble re-locating it.

Something very ironic there!

References

Links will take you to a site to download pdfs of the papers.

Douglas, B. J. 1986. Lignite resources of Central Otago. New Zealand Energy Research and Development Committee Publication P104: Volume one, Volume 2.

Pocknall, D.T., 1982. Pollen and spores from Blue Lake, St Bathans (H41) and Harliwichs Lignite Pit, Roxburgh (G43), Central Otago, New Zealand. Palynology Section, NZGS, Lower Hutt.

Pole, M.S., 1992. Early Miocene flora of the Manuherikia Group, New Zealand. 2. Conifers. Journal of the Royal Society of New Zealand 22, 287-302.

Pole, M.S., 1997. Miocene conifers from the Manuherikia Group, New Zealand. Journal of the Royal Society of New Zealand 27, 355-370.

McGlone, M. S., S. J. Richardson, et al. 2010. Comparative biogeography of New Zealand trees: species richness, height, leaf traits and range sizes. New Zealand Journal of Ecology 34: 1-15.

Pole, M., 2007. Conifer and cycad distribution in the Miocene of southern New Zealand. Australian Journal of Botany 55, 143-164.

Pole, M., 2008. Dispersed leaf cuticle from the Early Miocene of southern New Zealand. Palaeontologia Electronica 11 (3) 15A:, 1-117.

Pole, M., 2014. The Miocene climate in New Zealand: Estimates from paleobotanical data. Palaeontologia Electronica 17, 1-79, palaeo-electronica.org/content/2014/2780-miocene-climate-of-new-zealand.

 

Fossil pea pod (legume) from the Miocene of New Zealand
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Giant Pea Pod fossils in New Zealand’s Miocene

Pea pod fossils in New Zealand were first found by Aline Holden, a pioneer of New Zealand plant fossil research. She found the first ones at Bannockburn in 1981, while working on her PhD, and then found more in the Nevis Valley.

In 1987, my PhD professor, J.D. Campbell and his wife, Anne, dropped in unexpectedly in Alexandra (my home). They were on their way to the Nevis Valley and wanted to know if I would come too. The Nevis Valley has a well-known oil shale deposit, and this includes fossil leaves and scattered fish bones of Miocene age (c. 18-17 million years). Once in the area, ‘JDC’ focussed on shale near the track, while I set off to explore up a shrubby side valley. I was on the way back when I spotted a likely outcrop up on the valley side. It was solid gold – to a fossil plant person that it is. Technically it was mudstone, but stuffed full of not only fossil leaves, but pea pods as well. I worked out as large a chunk as I could, strapped it to my pack frame, and then staggered back to the car with it.

Back in the lab, chipping away the overlying mudstone, revealed fossil pods (legumes) up to 130 mm long, and with 14 peas (seeds).

Fossil pea pod (legume) from the Miocene of Nevis Valley, New Zealand

Fossil pea pod (legume) from the Miocene of Nevis Valley, New Zealand (length c. 130 mm)

Today New Zealand has just four groups of peas (the legume family). There’s kowhai (Sophora), Kakabeak (Clianthus), the scree pea (Montigena) and the many brooms (Carmichaelia). All of these are part of the legume family that have classic ‘pea flowers’. One of the technical terms for this group is (or was) the Papilionoideae (think of the French word for butterfly – ‘papillion’).

But traditionally, there are also two other large groups of legumes. One is the Caesalpinioideae – with quite showy flowers (think Bauhinia), then the Mimosoideae. These have very reduced flowers, looking a bit like pom-poms (think of the wattles/Acacia).

Fossil pea pod (legume) from the Miocene of Bannockburn, New Zealand

Fossil pea pod (legume) from the Miocene of Bannockburn, New Zealand

The lucky find in the Nevis that day was not just the large fossil pea pods, some with the seeds (peas) in them, but some scattered leaves that were surely produced by the same plant. Based on the combination of evidence, the legume expert Dr Les Pedley, suggested most likely identification of the fossils was Serianthes. This plant is now found in New Caledonia, Fiji, and French Polynesia.

Fossil legume leaflet from the Miocene of Bannockburn, New Zealand

Fossil legume leaflet from the Miocene of Bannockburn, New Zealand

Serianthes is one of the Mimosoideae group. The Mimosoideae was already known in New Zealand based on fossil pollen, although in those cases, Acacia was considered the more likely parent plant (Pocknall and Mildenahll 1984; Mildenhall and Pocknall 1989).

Together, the pods, leaves and pollen make a nice addition to what used to grow in New Zealand. But what do these fossil mean? Based on where Serianthes grows today, the average annual temperature may have been more than 20 C. That’s about twice what it is now. Also a suspicion that the vegetation it was growing in was relatively dry.

I seem to spend half my life staggering kilometres with a pile of rock, either on my back or worse, carrying it in my arms. But in this case, it was well worth it.

References

Links will take you to my academia.edu site where you can download a pdf.

Mildenhall, D.C., Pocknall, D.T., 1989. Miocene-Pleistocene spores and pollen from Central Otago, South Island, New Zealand. New Zealand Geological Survey Palaeontological Bulletin 59, 1-128.

Pocknall, D.T., Mildenhall, D.C., 1984. Late Oligocene -Early Miocene spores and pollen from Southland, New Zealand. New Zealand Geological Survey Paleontological Bulletin 51, 1-66.

Pole, M.S., 1992. Fossils of Leguminosae from the Miocene Manuherikia Group of New Zealand, in: Herendeen, P.S., Dilcher, D.L. (Eds.), Advances in Legume Systematics: Part 4. The Fossil Record. The Royal Botanic Gardens, Kew, pp. 251-258.

Pole, M.S., Holden, A.M., Campbell, J.D., 1989. Fossil legumes from the Manuherikia Group (Miocene), Central Otago, New Zealand. Journal of the Royal Society of New Zealand 19, 225-228.

Araucaria fossil shoot from Miocene of New Zealand.
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Hoop Pine fossils – dry rainforest in New Zealand’s Miocene

In a little patch of shale, continually flaking onto the road near Bannockburn (central South Island, New Zealand), there are the unmistakable fossils like Australian ‘hoop pine’ shoots. Hoop pines are members of the tree family which includes ‘monkey puzzles’, ‘bunyas’ and the ‘Norfolk Island Pines’. The Latin name is Araucaria – New Zealand has none of these in its native flora today, but it does have the kauri (it’s another genus, Agathis, but in the same family).

A long fossil Araucaria shoot from the Miocene of Bannockburn, New Zealand. Shoot is c. 6 mm wide.

A long fossil Araucaria shoot from the Miocene of Bannockburn, New Zealand. Shoot is c. 6 mm wide.

Around 17 million years ago (Miocene period) the shale would have been accumulating in a standing body of water, probably a flood-basin lake. Plant fossils would have been washed into it after they blew off a tree into a river, which then flowed into the body of water. The pine shoots are made of long, overlapping scale-like leaves, that together make a tail-like structure, maybe 4-6 mm in diameter. Along with the shoots there are also occasional  seed cone-scales and rare pollen cones. The cone-scales have delicate wings, just like modern hoop-pines, but these have often been lost in the fossil.  These additional plant fossils all help to show that the original tree was something much closer to the Australian ‘hoop pines’, the Norfolk Island pine’ and some New Caledonian species of Araucaria, than to other species in the family.

A fragment of a branch of fossil Araucaria shoots from the Miocene of Bannockburn, New Zealand

A fragment of a branch of fossil Araucaria shoots from the Miocene of Bannockburn, New Zealand

Back in the days of the dinosaurs (Cretaceous, c. 75 million years ago) the hoop pine family was common in New Zealand. They were an important component of the wet coal-swamps. But at the same time the dinosaurs vanished, so did those trees. From that time on, fossils of Araucaria are rare in New Zealand, with the layer of shale near Bannockburn an exception.

A fossil Araucaria seed-cone scale from the Miocene of Bannockburn, New Zealand (c. 20 mm high)

A fossil Araucaria seed-cone scale from the Miocene of Bannockburn, New Zealand (c. 20 mm high)

What do these fossils mean? Probably warmer times than today, but perhaps more intriguingly, the Australian hoop pine is a key plant in what are called ‘dry rainforests’. This term sounds a bit contradictory, but it refers to forest where rainfall is relatively low, but where fire does not normally occur. Unlike wetter, more normal rainforests, the low rainfall helps keep the forest canopy more open. Without so much shade, the greater amount of light reaching the forest floor is probably a reason why the hoop pines live in them. It’s certainly a very different habitat than the coal swamps where their relatives lived in along side dinosaurs.

The Bannockburn fossil ‘hoop pines’ (using the term broadly to refer to a group pf species) are evidence of forest (the area was virtually treeless when Europeans arrived in the 19th century),  warmer conditions than in southern New Zealand today (and more like southeastern Queensland), but with some sort of degree of ‘dryness’ – probably seasonally low rainfall.

Small-stuff, but it’s bits of evidence like this that climatologists can use to figure out exactly how our climate system changes.

 

References

Links will take you to my Academia.edu page where you can download a pdf.

Pole, M.S., 1992. Early Miocene flora of the Manuherikia Group, New Zealand. 2. Conifers. Journal of the Royal Society of New Zealand 22, 287-302. (describes the Araucaria shoot, seed-cone and pollen cone fossils from Bannockburn)

Pole, M.S., 1993. Early Miocene flora of the Manuherikia Group, New Zealand. 10. Paleoecology and stratigraphy. Journal of the Royal Society of New Zealand 23, 393-426. (proposes the dry rainforest interpretation for the shale at Bannockburn)

Pole, M., 2008. The record of Araucariaceae macrofossils in New Zealand. Alcheringa 32, 405–426. (describes cuticle from the Araucaria fossils at Bannockburn)

Palaeontologia Electronica 17, Issue2;27A; 79p;palaeo-electronica.org/content/2014/780-miocene-climate-of-new-zealand (detailed evaluation of New Zealand’s climate at the time of the Bannockburn shale and its Araucaria fossils)

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Webb, L.J., 1959. A physiognomic classification of Australian rainforests. Journal of Ecology 47, 551-570. (defines ‘dry rainforest’ in Australia and Araucaria as one of their keys)

 

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New Zealand’s Hawks Crag Breccia – prelude to the drift from Gondwana

The New Zealand road network has some seriously quirky idiosyncrasies – little things we locals take for granted, but can cause some alarm to the ever-increasing number of tourists. There are, for example, hundreds of ‘one lane’ bridges. And about these,  I was once asked, in total exasperation by an American “Why don’t you just build two-lane bridges?!” (I dunno, cause they cost twice as much?). But on encountering one of those one lane bridges up near Hokitika – that also include the railway line, he was speechless.

Another quirky New Zealand road is that which claws its way around Hawks Crag, a steep bluff above the Buller River. You’ll encounter it if you drive from Westport towards Murchison. It’s one-way, and, in contrast to one-way bridges, because of the curve, you can’t see if there is on-coming traffic. There are now traffic lights, but a sign asks you that if the lights aren’t working (they weren’t last time I drove it) to be-careful.

The one-way road clawing its way around Hawks Crag, above the Buller River in New Zealand.

The one-way road clawing its way around Hawks Crag, above the Buller River in New Zealand.

The bluff that the road cuts around is’Hawks Crag’, and the rock its self is a ‘breccia’, composed of angular rock fragments in a finer matrix. Hence the formation that the road cuts through is called the Hawks Crag Breccia. It’s one of the more intriguing units of New Zealand geology.

The origin of the Breccia is relatively clear – it is the accumulation of material on a ‘fan’ – along the edge of an actively-growing mountain (this type of rock is sometimes called a ‘fanglomerate’). The rocks have not traveled far -rivers have not rounded or sorted the boulders. Material simply poured off active fault scarps into a basin. However, for many years the age of the Hawks Crag Breccia was unclear. Partially this was due to the nature of the breccia itself. It is largely devoid of fossils. But there are a few mudstone beds that would have been flood basins or swamps, and these did prove to have fossil spores. But many of these fossils were new – they were found no-where else, and thus could not be correlated elsewhere. From a variety of reasons, an early conclusions was that the Breccia was Jurassic (Couper, 1953, 1960). However, this was a problem, as the fledgling science of radiometric dating rocks at the same time concluded that the boulders in the breccia, were Cretaceous (Aronson 1965). The age of the rocks in the breccia of course, cannot be younger than the breccia itself. Either the radiometric date, or the date based on fossils, had to be wrong.

Detailed view of the Hawks Crag Breccia - an unsorted pile of sharp-edged rocks.

Detailed view of the Hawks Crag Breccia – an unsorted pile of sharp-edged rocks.

Eventually 30 species of plant fossils were found in the Hawks Crag Breccia (Norris 1968) – and fortuitously, at the same time, a detailed study of similar fossils in the Cretaceous of Australia became available (Dettmann and Playford 1968). This led to confirmation of a  mid Cretaceous age (late Albian, c. 105 Ma) of the Hawks Crag Breccia (Norris and Waterhouse, 1970; Waterhouse and Norris 1972; Raine 1984). There was no longer a problem with the age of the boulders – they were formed slightly before they entered the breccia. Several plant species that grew at Hawks Crag were also in eastern Australia. In some respects this is not surprising, as at the time, not only were they closer, but you could have walked from this part of New Zealand to Australia, or even Antarctica.  New Zealand was peripheral to, and only just breaking away from, the continent of Gondwana.

The plant fossils of the Hawks Crag Breccia (Norris 1968) are a diverse mix of lycopods, ferns (including tree ferns), podocarp and araucarian conifers, as well as the pollen of an extinct conifer family, the Cheirolepidiaceae. In some respects, the particular pollen and spore fossils are reminiscent of the cool and wet New Zealand vegetation today – but with one major difference – there were no flowering plants. These arrived in New Zealand very shortly (a million or two years or so) after the Hawks Crag Breccia accumulated.

The Hawks Crag Breccia is now understood to be one rock type in a broader system – the Porari Group. For example, the very different Bullock Formation is made up largely of mudstone. This has been interpreted as a lake, or series of lakes, into which the Hawks Crag fans flowed (Laird 1995). The Porari Group is now scattered over about 320 km of the West Coast, as well as there being similar deposits east of the Alps (Laird 1995). One could thus think of a ‘Porari Landscape’ or even a ‘Porari Ecosystem’.

In the broader picture the deposition of the Hawks Crag Breccia, and the whole Porari Group, was related to the Rangitata Orogeny – the period of mountainous upheaval that preceded the New Zealand region breaking away from the rest of Gondwana (Carter et al. 1974; Waterhouse and Norris 1972; Adams and Nathan 1978). The Rangitata Orogeny is one of New Zealand’s major periods of geological change where the regime went from compressional to extensional and eventually led to New Zealand drifting into the Pacific (Laird and Bradshaw 2004).

Schematic diagram (simplified from Schulte et al., 2014) to show the the Porari Group (including the Hawks Crag Breccia) forming on the flanks of a Metamorphic Core Complex.

Schematic diagram (simplified from Schulte et al., 2014) to show the the Porari Group (including the Hawks Crag Breccia) forming on the flanks of a Metamorphic Core Complex.

In detail, the Hawks Crag Breccia can also be placed into a more recent concept – the Metamorphic Core Complex (Tulloch and Kimbrough, 1989; Schulte, et al., 2014). These form in extensional environments, and consist of a central core of deeper, older rock that rises to the surface and is typically intruded by granites, while breccia-filled half-graben valleys develop on the flanks.

I wonder how long it will be before some local-Councillor gets it into his or her head to blast away this quirky stretch of road, to enable more people to get through, faster? In the meantime, just keep driving carefully, watch out for on-coming traffic. and the odd person having a closer look at the Hawks Crag Breccia.

References (links will take you to a downloadable pdf)

Adams, C.J.D., Nathan, S., 1978. Cretaceous chronology of the Lower Buller Valley, South Island, New Zealand. New Zealand Journal of Geology and Geophysics 21, 455-462.

Aronson, J.L., 1965. Reconnaissance rubidium—strontium geochronology of New Zealand plutonic and metamorphic rocks. New Zealand Journal of Geology and Geophysics 8, 401-423.

Carter, R.M., Landis, C.A., Norris, R.J., Bishop, D.G., 1974. Suggestions towards a high-level nomenclature for New Zealand rocks. Journal of the Royal Society of New Zealand 4, 5-18.

Couper, R.A., 1953. Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand. New Zealand Geological Survey Palaeontological Bulletin n.s. 22, 77.

Couper, R.A., 1960. New Zealand Mesozoic and Cainozoic plant microfossils. New Zealand Geological Survey Paleontological Bulletin 32, 88 pp.

Dettmann, M.E., Playford, G., 1968. Taxonomy of some Cretaceous spores and pollen grains from eastern Australia. Proceedings of the Royal Society of Victoria 81, 69-93.

Laird, M.G., 1995. Coarse-grained lacustrine fan-delta deposits (Pororari Group) of the northwestern South Island, New Zealan: evidence for Mid-Cretaceous rifting. Special Publication of the International Association of Sedimentologists 22, 197-217.

Laird, M.G., Bradshaw, J.D., 2004. The Break-up of a Long-term Relationship: the Cretaceous Separation of New Zealand from Gondwana. Gondwana Research 7, 273-286.

Norris, G., 1968. Plant microfossils from the Hawks Crag Breccia, south-west Nelson, New Zealand. New Zealand Journal of Geology and Geophysics 11, 312-344.

Norris, G., Waterhouse, J.B., 1970. Age of the Hawks Crag Breccia. Transactions of the Royal Society of New Zealand. Earth Sciences 7, 241-250.

Raine, J.I., 1984. Outline of a palynological zonation of Cretaceous to Paleogene terrestrial sediments in west coast region, south island, New Zealand. New Zealand Geological Survey Report 109, 1-82.

Schulte, D.O., Ring, U., Thomson, S.N., Glodny, J., Carrad, H., 2014. Two-stage development of the Paparoa Metamorphic Core Complex, West Coast, South Island, New Zealand: Hot continental extension precedes sea-floor spreading by ~25 m.y. Lithosphere 6, 177-194.

Tulloch, A.J., and Kimbrough, D.L., 1989, The Paparoa Metamorphic Core Complex, New Zealand: Cretaceous extension associated with fragmentation of the Pacific margin of Gondwana: Tectonics, 8, 1217–1234.

Waterhouse, J.B., Norris, G., 1972. Paleobotanical solution to a granite conundrum: Hawks Crag Breccia of New Zealand and the tectonic evolution of the southwest Pacific. Geoscience and Man 4, 1-15.

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The Lost Forest of the Ashley River, Canterbury, New Zealand

A gem in the heart of Christchurch is Riccarton Bush (sometimes called Deans Bush). It’s a patch of original kahikatea forest, just a few hundred meters from the Riccarton shopping center (See Molloy,1995, for pretty much all you need to know about the forest).

As anyone who flies in or out of Christchurch, or drives that dead-boring road to Timaru can see, the Canterbury Plains are as ecologically-devastated as an area can get. Not just flat, but the native vegetation has simply been replaced with something else. There was, and remain, patches of native forest on the Banks Peninsula high-ground, and likewise where the foothills meet the plains, such as Geraldine and Oxford (Clark 1926). But for the Plains, Riccarton Bush is pretty much it. It really is a miracle that this one little patch has been preserved. Added to the data collated by Molloy and Brown (1995) of relict living trees, old stumps and charcoals, it is clear that there were once at least patches of forest on the good alluvial soils.  Without Riccarton Bush, it would be so much harder to believe that forest once grew on the Canterbury Plains.

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The interior of Riccarton Bush.

Much of the ‘subfossil’ evidence for ancient forests comes from transient exposures in gravel pits or road works, but Benfield (2011)and Molloy (1995, Plate 9) illustrated stumps of a lost forest in a channel of the Ashley River. I don’t share Benfield’s views on 1080 poison, but his interest in the remains of the forest in the Ashley River fascinated me, and led me to have a look for myself.

As is so often the case (with me, anyway) I spent ages floundering around an overgrown, weedy area, along the river bank, then threading my way through a pile of blackberry (I made the most of this by eating lots and giving myself a stomach ache) before giving up, and finally finding some remains of the forest on the way back to the car.

IMG_0757

A single large conifer stump in the Ashley River.

What I came across was one large tree stump, projecting from flowing water up to my thighs (see the featured image). It is one of the podocarp conifers, probably totara, or perhaps kahikatea or matai, although I haven’t worked out which yet. There were a few smaller stumps, totally submerged, a little downstream. The broad location is c. 28 km north of the center of Christchurch, and more precisely, 600 m  upstream of the bridge over the Ashley River near the right bank. A radiocarbon date on an Ashley River stump (NZ 14C No 7680) reported in Molloy and Brown (1995) provided an age of c. 870 years before 1950.

The radiating roots of a submerged stump in the Ashley River are just visible - and another stump is just upstream.

The radiating roots of a submerged stump in the Ashley River are just visible – and another stump is just upstream.

Benfield’s (2011) personal experience shows that even this small group of stumps was more extensive up until a few years ago. Development has either destroyed or re-buried much of it. Forests such as the one in the Ashley or Riccarton, owe their existence to the dynamic nature of braided rivers – with periodic fresh alluvial deposits or old channels becoming available for a new cohort of seedlings. The abruptly changing channels can also be their demise, or leave them standing in water as a ‘swamp forest’. Travelers down the West Coast will be familiar with the sight of semi-submerged kahikatea forests, for instance at Lake Wahapo or Ship Creek. These postcard examples help give rise to the belief that kahikatea prefers to grow in standing water, and in high rainfall areas.

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Kahikatea trees in Lake Wahapo – with a c. 1m lower water level than normal.

However, it’s the Canterbury Plain evidence that helps confirm that kahikatea is also a tree of drier rainfall, provided the soils, and the groundwater table (Webb, 1995), suit. Ryan (1995) gives a figure of 668 mm as the average annual rainfall of the Christchurch Botanical Gardens – relatively low for New Zealand forests. These drier forests were most prone to being destroyed by fire once humans arrived on thee scene, thus distorting their apparent climatic preferences towards the wet end of the spectrum, Tellingly, Benfield (2011) observed that the Ashley River forest appeared to have been burnt.

A take-home message from this, is that the soils and the rainfall of the Canterbury Plains are fine for some of our native forests. Imagine a revived network of forest patches across the Plains – spaced within walking/cycling distance of Christchurch. Something to break that awful tedium of farms. It’s something I think about every time I drive past our ever increasing roadside plantings of natives. It can be done, and it just may have started.

References

Benfield, W.F. 2011. The Third Wave, Poisoning the Land. Tross Publishing, Wellington.

Clark, A.F. 1926. Canterbury’s native bush. TeKuraNgahere, New Zealand Journal of Forestry, 2, 15-22.

Molloy,  B. 1995. Riccarton Bush: Putaringamotu. The Riccarton Bush Trust, Christchurch.

Molloy, B. and Brown, L. 1995. Vegetation history. pp. 85-115 in: Molloy,  B. (Ed.) Riccarton Bush: Putaringamotu. The Riccarton Bush Trust, Christchurch.

Ryan, A. 1995. Climate & Weather. pp. 69-82 in: Molloy,  B. (Ed.) Riccarton Bush: Putaringamotu. The Riccarton Bush Trust, Christchurch.

Webb, T. 1995. Soils & Landforms.pp. 59-68  in: Molloy,  B. (Ed.) Riccarton Bush: Putaringamotu. The Riccarton Bush Trust, Christchurch.

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Phyllocladus fossils from the Miocene of New Zealand, and Cretaceous Protophyllocladus

A rare plant fossil in the Miocene Manuherikia Group of New Zealand, is Phyllocladus (the Celery Pine). This is a strange conifer which, instead of leaves, the adult plant has multi-veined flattened branches that are called phylloclades. With these phylloclades, the average person would scarcely believe Phyllocladus is a kind of conifer (very broadly, a pine). But it is common in some parts of New Zealand today (typically in ‘difficult’ places, cold, or with poor soils) and also in Tasmania and Malaysia.

Fossil pollen suggests Phyllocladus has been in New Zealand since the Eocene (Mildenhall 1980). There are somewhat similar, but older pollen records,  for example from New Zealand’s Late Cretaceous (Couper, 1953; Cookson & Pike, 1954) but these are likely to represent something distinct. Despite conifers being very diverse in the Miocene St Bathans Paleovalley sediments of the Manuherikia Group,  Phyllocladus appears to have been absent there (Pole 1992a, 1997, 2007). The climate may have been so warm, and the soils rich enough, to preclude it (Pole 2014). However, Phyllocladus is present in the Miocene Nevis Oil Shale (Pole 1992, see figured image), which was deposited in very different conditions (Douglas 1986). There are hints from the Nevis, including large fossil legumes (Pole et al. 1989, 1992b) that the climate may have had a distinct dry season. This may have favoured Phyllocladus. DNA evidence suggest the extant New Zealand species only radiated in the Late Cenozoic (Wagstaff, 2004), and there are certainly Phyllocladus fossils from this time (e.g. From Mataora, in the Coromandel. Pole and Moore, 2011).

Fossil Phyllocladus from Mataora, New Zealand.

Fossil Phyllocladus from Mataora, New Zealand.

Phylloclades appears to be a strategy to increase light-intercepting area beyond that of typical, simple, needle-like leaves ( e.g. Brodribb 2011). In essence, Phyllocladus is trying to become more like the broad leaves of typical flowing plants, in order to compete with them. Separate from that hypothesis, there seems to be an unstated assumption – that the world’s forests became darker, shadier places, with the evolution of broad-leaved flowering plants. But did they? Conifer forests can be damned dark under the canopy. An individual pine needle doesn’t create much shade, but a whole lot of them do.

Extant Phyllocladus IMG_0714

In one of the places I lived in for a few years in Brisbane, my neighbour on the opposite side of the street was Ray Specht. There was a big Eucalyptus tree growing between his house and mine. Ray happened to be one of the most influential people in Australian botany. For example, the various schemes of Australian vegetation classification mostly stem from him. On visiting Ray, the conversation would usually quickly go to the 1948 American-Australian Scientific Expedition to Arnhem Land, which was clearly a highlight of his life.   Ray would expound on the expedition until his wife would look up from her book and go “Oh Ray – shut up!”  Then, fascinating as the Expedition was, I could get him back to what I really wanted him to talk about – his views on how vegetation structure could be predicted from basic environmental properties.

One of Specht’s understandings was that the amount of shade under the canopy of a forest was fundamentally determined by the environment. Basically, closed canopy forests (like rainforests) are more open underneath the canopy, whereas open canopy forests (like Eucalyptus forests) have a denser zone of shrubs. Down near the ground, things even out. There are no doubt plenty of botanists who might take issue with the details, but I find it a valuable insight. At least in Specht’s view, given the right environmental conditions,  forests would have been just as dark and shady before flowering plants evolved, as after.

I’ve wondered if any other fossils might be helpful. In fact, there is a fossil plant with the intriguing name Protophyllocladus has long been known from Cretaceous rocks right across the Northern Hemisphere. In terms of gross morphology, it has phylloclades uncannily like Phyllocladus. However, their detailed structure,  and its affinities, have remained unclear up until very recently. But in 2014 the Russian scientists Natalya Nosova and Lena Golovneva from St Petersburg made a detailed study of the fossil epidermis of Protophyllocladus and compared it with Phyllocladus (Nosova and Golovneva 2014). They concluded Protophyllocladus was a conifer, and likely in the same family as Phyllocladus (the Podocarpaceae).  Protophyllocladus is much older than Phyllocladus, but it still comes from a time when flowering plant forests had spread across the Northern Hemisphere (see fig. 7 in Pole et al. 2016). In that respect, it is consistent with the idea that phylloclades evolved in response to the spread of flowering plants. If fossils of conifers with phylloclades turn up from pre-angiosperm times, then Spechts’ ideas should be looked at closely.

Extant Phyllocladus trichomanoides

Extant Phyllocladus trichomanoides

However, my feeling is that the epidermal morphology of Protophyllocladus is distinct from Phyllocladus or any of the extant related plants (the family Podocarpaceae). For instance the epidermal cells of Protophyllocladus  do not often occur in files. That is, I think the phylloclades of Protophyllocladus probably evolved quite independently of Phyllocladus.

Lightening, so it is said, never strikes the same place twice. But of course, we know this is wrong – lightening does hit some places multiple times and even the odd person has been struck more than once. I think of evolutionary developments as a bit like lightening striking a particular place (a new morphological feature evolves), but just occasionally, it strikes there again (and a similar feature evolves in another lineage. The technical term for this is ‘convergent evolution’. I suspect the phylloclades of Protophyllocladus and Phyllocladus are convergent evolution.

And that big Eucalyptus between my place and Ray Spechts’ ? According to him – it had been hit by lightening at least three times.

References

Links will take you to a site to download pdfs of the papers.

Brodribb, T.J., 2011. A functional analysis of podocarp ecology, in: Turner, B.L., Cernusak, L.A. (Eds.), Ecology of the Podocarpaceae in Tropical Forests, Smithsonian Contributions to Botany, No. 95. . Smithsonian Institution Scholarly Press, Washington, D.C., pp. 165-173.

Douglas, B. J. 1986. Lignite resources of Central Otago. New Zealand Energy Research and Development Committee Publication P104: Volume one, Volume 2.

Mildenhall, D.C., 1980. New Zealand Late Cretaceous and Cenozoic plant biogeography: a contribution. Palaeogeography, Palaeoclimatology, Palaeoecology 31, 197-233.

Nosova, N., Golovneva, L., 2014. The Mesozoic genus Protophyllocladus Berry (Pinopsida). Review of Palaeobotany and Palynology 210, 77–88.

Pole, M.S., 1992a. Early Miocene flora of the Manuherikia Group, New Zealand. 2. Conifers. Journal of the Royal Society of New Zealand 22, 287-302.

Pole, M.S., 1997. Miocene conifers from the Manuherikia Group, New Zealand. Journal of the Royal Society of New Zealand 27, 355-370.

Pole, M., 2007. Conifer and cycad distribution in the Miocene of southern New Zealand. Australian Journal of Botany 55, 143-164.

Pole, M., Moore, P.R., 2011. A late Miocene leaf assemblage from Mataora, Coromandel, New Zealand and its climatic implications. Alcheringa 35, 103-121.

Pole, M.S., 1992. Fossils of Leguminosae from the Miocene Manuherikia Group of New Zealand, in: Herendeen, P.S., Dilcher, D.L. (Eds.), Advances in Legume Systematics: Part 4. The Fossil Record. The Royal Botanic Gardens, Kew, pp. 251-258.

Pole, M.S., Holden, A.M., Campbell, J.D., 1989. Fossil legumes from the Manuherikia Group (Miocene), Central Otago, New Zealand. Journal of the Royal Society of New Zealand 19, 225-228.

Pole, M., Wang, Y., Bugdaeva, E.V., Dong, C., Tian, N., Li, L., Zhou, N., 2016. The rise and demise of Podozamites in east Asia—An extinct conifer life style, . Palaeogeography, Palaeoclimatology, Palaeoecology.

Wagstaff, S.J., 2004. Evolution and biogeography of the austral genus Phyllocladus (Podocarpaceae). Journal of Biogeography 31, 1569–1577.

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Aboriginal Paintings of the Kimberley- very old Pleistocene or not so old Holocene?

Many of the real advances in science seem to come from a sudden ‘insight’ ( think Archimedes and “Eureka!”) – and there is often no simple connection between collecting data and that ‘aha!’ moment.  The tedious data collection happens, but at some moment, the brain, perhaps quite subconsciously, puts two and two together, and comes up with something more than four. Grahame Walsh was a man who dedicated most of his life to studying the ancient rock paintings of Australia. After having spent about twenty years recording paintings in the Canarvon Gorge region of Queensland (and many other parts of the state), he also spent thirty working in the Kimberley – the remote, north-west corner of the continent.

The extraordinary Grahame Walsh - an authority on Australian rock paintings.

The extraordinary Grahame Walsh – an authority on Australian rock paintings.

The fundamental part of his research was a grueling regime of surveying. Scattered over the rock outcrops in the Kimberley there is a series of often very distinct painting styles. There are rock faces where there are layers of paintings, one over the other. Oddly, the older paintings are often better preserved than the younger, as they are ‘sealed’ by a layer of natural silica varnish.  These superimposed layers provide a kind of stratigraphy of painting styles, and persistent study by Walsh and others, worked out the relative order of these painting styles. But the big mystery, was not the relative but the absolute date. Just how old were they? Almost all of the sites with paintings do not have associated archaeological  material that can be easily  dated.

Thousands of years of overlapping rock paintings in Australia's Kimberley region. Instances like these provide a kind of 'stratigraphy' that allowed researchers such as Grahame Walsh, to work out the relative order of painting styles.

Thousands of years of overlapping rock paintings in Australia’s Kimberley region. Instances like these provide a kind of ‘stratigraphy’ that allowed researchers such as Grahame Walsh, to work out the relative order of painting styles.

Walsh came up with a compelling scenario. A part of the painting style sequence could be interpreted as passing from an earlier time of abundance, where the paintings emphasised personal adornment, with no indication of aggression or violence. These have been called the ‘Bradshaw’ style, although ‘Gwion’ is used by some researchers (see figure below and the featured image).  The paintings then become militaristic, including regimented ‘toy soldier’ like individuals, with weapons. Then there was an apparent long gap, where no paintings were made, but existing paintings were ‘sealed in’ with a layer of natural rock varnish. After an unknown period of time, painting began again, but in an entirely different style. These continued to be painted until the Europeans invaded.

An example of the Bradshaw style of Kimberley rock paintings. Nice the costume 'finery' and ornate hair styles.

An example of the Bradshaw style of Kimberley rock paintings. Nice the costume ‘finery’ and ornate hair styles.

To Walsh, it seemed like this particular sequence recorded first a time of resource abundance – essentially ‘good-times’, which then passed to scarcity, resulting in violence. Then there was a time gap – when environmental conditions may have been so bad, that no one was in the area at all. Finally, when conditions improved again, a new culture moved into the area with different ideas about what to paint. Walsh’s insight was to suspect that this sequence was the run-up to the peak of the Last Glacial Maximum (around 17,000-21,000 years ago), and then the return to good times in the post-glacial Holocene. At Glacial Maximum, there was so  much water tied up in the worlds ice caps, that parts of Australia became super dry and humans were probably driven out of some areas – hence a gap in painting.  It was so dry that constant dust storms were blowing – and these were the cause of  the rock varnish.

Confirming this scenario was the problem. Walsh collaborated with some other researchers who had developed specialised techniques to date minute pieces of material. Richard Roberts used a technique (Optically Stimulated Luminescence – OSL)  that determines how long ago quartz grains were exposed to sunlight. The brilliant part here is that mud wasps in the Kimberley build their nests in the same rock overhangs as the paintings. Mud containing quartz grains is collected bit by bit by the wasp- and it is exposed ti the sun. But when it gets packed away into a next, it is sealed in darkness.

The core of one mud wasp nest yielded an age of  around 17,500 years (Roberts et al. 1997). This implied that a possible Bradshaw figure was even older, and the stencil of a hand below that, older still. It meant that these were painted at, or even before the Last Glacial Maximum. It supported Walsh’s insight. This date makes the Bradshaw Paintings remarkably old – perhaps older than the famous paintings at Lascaux in France, which are about 18,000 years old.

An example of a typical rock outcrop with Bradshaw rock paintings. There may be hundreds of paintings in such a spot - but little or no trace of who painted them in the ground below.

An example of a typical rock outcrop with Bradshaw rock paintings. There may be hundreds of paintings in such a spot – but little or no trace of who painted them in the ground below.

Another researcher involved in the study of the paintings was Alan Watchman. One of his specialties is the carbon dating very small fragments, and as well, he has an interest in the kind of rock varnish that covers the older paintings. Watchman collaborated with Walsh to collect material from paintings that could be dated, for example, a beeswax resin component . However, when he published his results, in the same year as Roberts and co-authors work on the mud wasp nests (Watchman 1997; Watchman et al. 1997), Walsh was not included as a co-author, and Watchman came up with very different results. Watchman’s pioneering estimates for the age of some Bradshaw figures and some from an even older painting style, were in the range of (only) 3,000-4000 years.

An example of a much younger painting style than the Bradshaws.

An example of a much younger painting style than the Bradshaws.

Robert’s Pleistocene results came under intense scrutiny. For instance, Aubert (2012) focused on both the location of the wasp nests with relation to the paintings, and details of their sampling and, in a blow to Team-Walsh,  concluded that there was “no substantial evidence” for a Pleistocene age. On the other hand, Bednarik (2014) threw a life-line to Team-Walsh by arguing that the organic material within the paint residues  may have been “acquired subsequent to the time of rock art production”.  In other words, there was now a mechanism to account for the young dates obtained by Watchman, but still have old paintings.

However, at around this time another group of workers came up with a new scenario for the sequence of Kimberley paintings.  They basically agreed with Walsh about the climatic significance of a ‘gap’ – but they incorporated Watchman’s younger Holocene dates.  Based on a record of fossil pollen, charcoal and dust, McGowan et al. (2012) found evidence for an exceptionally dry phase in the Kimberley in the mid Holocene. Thus, they proposed that Walsh’s ‘gap’ was not at the height of the Last Glacial Maximum, but relates to a ‘mega drought’ that occurred around 6300-3400 years ago and which was triggered by changes in the El Niño Southern Oscillation. This paper got my attention, and it was what stimulated me to write this. Was Walsh’s claim of amazingly old paintings wrong after all?

Come 2016 and out came a new paper (Ross et al 2016) using the OSL technique on mudwasp nests. It was mostly  a new group of researchers and a far more rigorous procedure was used than the pioneering work of Roberts et al. The minimum age of one painting was established at 16,000 years old. Unfortunately that particular figure could not be clearly placed into one of Walsh’s painting styles. That is disappointing, but the important conclusion is that Pleistocene aged rock painting in the Kimberley has probably been solidly established. McGowan et al’s drought was surely real, but just not the cause of the gap in the painting sequence.

Science seems to jump forward with ‘insights’. They may or not actually be right, but they do tend to stimulate more research, and that’s a good thing. In any case, my money is on Walsh being on the mark.

References

Aubert, M., 2012. A review of rock art dating in the Kimberley, Western Australia. Journal  of Archaeological  Science 39, 573–577.

McGowan, H., Marx, S., Moss, P.T., Hammond, A., 2012. Evidence of ENSO mega-drought triggered collapse of prehistory Aboriginal society in northwest Australia. Geophysical Research Letters 39, L22702.

Morwood, M.J., Walsh, G.L., Watchman, A.L., 2010. AMS Radiocarbon Ages for Beeswax and Charcoal Pigments in North Kimberley Rock Art. Rock Art Research: The Journal of the Australian Rock Art Research Association (AURA) 27, 3-8

Roberts, R., Walsh, G., Murray, A., Olley, J., Jones, R., Morwood, M., Tuniz, C., Lawson, E., Macphail, M., Bowdery, D., Naumann, I., 1997. Luminescence dating of rock art and past environments using mud-wasp nests in northern Australia. Nature 387, 696-699.

Ross, J., Westaway, K., Travers, M., Morwood, M.J., Hayward, J., 2016. Into the Past: A Step Towards a Robust Kimberley Rock Art Chronology. PLoS ONE 11, e0161726. doi:0161710.0161371/journal.pone.0161726.

Walsh, G.L., 1994. Bradshaws: Ancient Rock Paintings of North-West Australia. The Bradshaw Foundation, Geneva.

Watchman, A.L., 1997. Dating the Kimberley rock paintings, in: Kenneally, K.F., Lewis, M.R., Donaldson, M., Clement, C. (Eds.), Aboriginal Rock Art of the Kimberley. The Kimberley Society, Perth, pp. 39-45.

Watchman, A.L., Walsh, G.L., Morwood, M.J., Tuniz, C., 1997. AMS radiocarbon dating age estimates for early rock paintings in the Kimberley, N. W. Australia: Preliminary results. Rock Art Research: The Journal of the Australian Rock Art Research Association (AURA) 14, 18–26.

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The Biggest Tree Stump in the Curio Bay Jurassic Forest

Back in the late 1980s I had the pleasure of meeting the English scientist David Bellamy. Bellamy was famous at the time as ‘The Botanic Man’, and he was in New Zealand to film for ‘Moa’s Ark’, a TV series and book about the development of New Zealand’s flora and fauna (including the extinct moa birds) over time. ‘Moa’s Ark’ describes the view that New Zealand broke away from the edge of Gondwana (in this case, Australia and Antarctica) and drifted into the Pacific with a compliment of life that was then preserved in isolation for many millions of years. I don’t subscribe to that view – but hats off to the series and the book (and the title!). They were an inspired bit of science communication.

Curio Bay is a petrified forest of Jurassic age, located in southernmost New Zealand. This was when New Zealand was firmly attached to Gondwana. You could have walked to what was going to become  Australia or Antarctica from Curio Bay at the time. If you wanted a place to start talking about the voyage of ‘Moa’s Ark’, you could hardly beat the real Gondwanan fossil forest at Curio Bay.

The largest tree stump in the Jurassic fossil forest at Curio Bay, New Zealand.

The largest tree stump in the Jurassic fossil forest at Curio Bay, New Zealand.

 

I ended up in contact with Bellamy because of my work on Curio Bay. I had mapped part of the forest, studied the rocks that encompass the fossil forest, and searched the coastline for many kilometers either side of it for additional clues.

Curio Bay seems to have been a first generation forest. There was a flood that deposited sediment over a large area, forming a ‘clean slate’ for a new forest to grow. When the forest was preserved – by another flood, silica from the sediment percolated the wood and preserved it. In many cases you can walk around the forest and can see at least some of the growth rings in the tree stumps. On this basis, most of the trees in the forest were rather young when they were preserved, say 50-60 years. There are a few that much older, perhaps around 200 years. These may have been the very first trees to colonise the new flood plain surface. Gradually, the space around them was filled in by more trees. The fact that there are growth rings at all, tells us that there was some kind of seasonality – perhaps temperature, or even light conditions (the forest grew much nearer the South Pole than it is today.

David Bellamy (arm outstretched) and his Moa's Ark crew beside the largest tree stump at the Jurassic fossil forest of Curio Bay, New Zealand (1989).

David Bellamy (arm outstretched) and his Moa’s Ark crew beside the largest tree stump at the Jurassic fossil forest of Curio Bay, New Zealand. (1989).

I showed David Bellamy and his crew around the fossil forest, taking them to what is the most prominent large fossil stump. The idea at the time was that Bellamy would be Robin Hood, in Sherwood Forest, England, and shooting off an arrow. The arrow was to fall, and bounce off one of the petrified logs at Curio Bay, and story would begin. When I pointed out the big stump, and its growth rings (see the featured image), Bellamy, a gifted communicator – placed the arrow head-down, its tip on one of the growth rings. “I wonder what story this might tell us?” he asked – and proceeded to run round and round the stump, like a record player (note to younger generations, these were devices to play music from flat disks. The typical speed was 33 rpm, or a faster 45 rpm). After a couple of revolutions, Bellamy announced: “Wrong speed!”, and ran round and round even faster.

“What story?” indeed. I’ve added to it, but Curio Bay and its fossil forest will have more to tell us yet.

References

*Clicking on these links will take you to my Academia.edu site, where you can download a pdf of the paper.

Pole, M.S., 2001. Repeated flood events and fossil forests at Curio Bay (Middle Jurassic), New Zealand. Sedimentary Geology 144, 223-242.

Pole, M.S., 1998. Structure of a near-polar latitude forest from the New Zealand Jurassic. Palaeogeography, Palaeoclimatology, Palaeoecology 147, 121-139.

Pole, M., 2004. Early-Middle Jurassic stratigraphy of the Fortrose-Chaslands region, southernmost South Island, New Zealand. New Zealand Journal of Geology & Geophysics 47, 129-139.

Pole, M., 2009. Vegetation and climate of the New Zealand Jurassic. GFF 131, 105 – 111.

 

 

 

Miocene Lauraceae leaf fossil
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The Amazing Miocene Fossil Leaf Pack of Mata Creek, New Zealand

I was crouched in a long boat somewhere up a rainforest-swathed river in Kalimatan, Borneo, when I saw it – a ‘living’ example of a fossil leaf pack I had once seen in New Zealand.

Our long boat is pulled up on the bank of a rainforested stream deep in Kalimantan (Indonesian Borneo) while others pass by.

Our long boat is pulled up on the bank of a rainforested stream deep in Kalimantan (Indonesian Borneo) while others pass by.

Several years before, I had been exploring down a little stream near St Bathans, New Zealand. I was looking for leaf fossils in sediments of an ancient river. The geological unit is a faulted mix of the St Bathans and Fiddlers Members (Douglas 1986) of the Manuherikia Group. This was deposited in the Miocene, about 20 million years ago, by rivers that meandered across a landscape that didn’t have the high topography of today,

In a low cut-bank of Mata Creek a layer had been exposed that looked like a stack of old newspapers charred by fire on their edges. Sandwiching this, above and below, was the more typical white sand laid down by the Fiddlers Member rivers.

A Miocene fossil 'leaf pack' - thousands of fossil leaves compacted together in the bank of Mata Creek, near St Bathans, New Zealand.

A Miocene fossil ‘leaf pack’ – thousands of fossil leaves compacted together in the bank of Mata Creek, near St Bathans, New Zealand.

The magic happened back in the lab. What looked like flakes of old newspaper, were in fact fossil leaves along with some small twigs. Long and gentle treatment with bleach turned the dark, opaque fragments into beautiful, golden and translucent specimens (see featured image). The stack of newspapers was in fact, a solid Miocene leaf pack – hundreds and hundreds of fossil leaves, all compressed together. Preservation was so good, that the outlines of epidermal cells could be seen under a microscope.

Many of these fossil leaves belong to the laurel family. They do not grow this far south in New Zealand today (it’s too cold), a good indication that in the Miocene, New Zealand was warmer than today. Some of the laurel leaves are ‘tripli-veined’, with three large veins radiating near the leaf base. This kind of laurel leaf is not found in New Zealand at all today, but is common in some other rainforests, in Australia for example.

The long boats of Kalimantan are ideal for navigating the little rivers or streams of the rainforest. They have a propeller that is barely submerged, making it possible to skim over shallows or submerged logs. They aren’t that conformable, and their engines usually aren’t muffled. After an hour or so of squatting on a wooden beam (or none at all), I was generally looking for any excuse to get out.

A leaf pack extending into the river on a point bar in Kalimantan.

A leaf pack extending into the river on a point bar in Kalimantan.

It was on one of these trips that I spotted a real, recently-made leaf pack. We were roaring along the discoloured water, almost covered by a canopy of rainforest trees, when I noticed a clear patch of the bank. Instead of being a densely vegetated green, it was dark grey, and had a layered appearance. We had the boat turned around and pulled up alongside.  It was a huge mass of leaves and twigs, separated by a smaller amount of silt. This was a perfect recent analogy of the fossil deposit that I had found in Mata Creek.

Close up view of a leaf pack on the point bar of a river in Kalimantan. A little below an to the left of the upper hand is a leaf very similar to the Miocene fossil shown in the featured image.

Close up view of a leaf pack on the point bar of a river in Kalimantan. A little below an to the left of the upper hand is a leaf very similar to the Miocene fossil shown in the featured image.

The best part was that I could now actually see – just where a leaf mat occurred in the river system, and how it had formed. The leaf mat was on a ‘point bar’. These are the inner parts of the meanders in a meandering river. While the outer part of the meander loop cuts into its bank,  the inner part grows by dropping sediment – and in this case, leaves.

Diagram illustrating where point bars (the yellow) occur in a meandering river. Arrows indicate the current direction. Fossil leaf mats can be deposited on these point bars.

Diagram illustrating where point bars (the yellow) occur in a meandering river. Arrows indicate the current direction. Fossil leaf mats can be deposited on these point bars.

Vast amounts of leaves are dropped into the river from the rainforest canopy. During floods, the leaves tend to get sorted from the silt because of their lower density and bigger size. When the currents drop, on the point bars, a layer of almost nothing but leaves can be deposited on ‘normal’ point bar sand.  Then, if the next flood doesn’t wash it away, it can be covered with a layer of sand – and a fossil leaf pack is in the making.

A view of another leaf mat, this one more clearly showing it has been covered by a layer of white sand.

A view of another leaf mat, this one more clearly showing it has been covered by a layer of white sand.

I’m a great fan of trying to see ‘living’ examples of what you come across in the geological record. In this case it made a welcome relief for a sore butt sitting in a Kalimantan long boat.

References

Links will take you to a site to download pdfs of the papers.

Douglas, B. J. 1986. Lignite resources of Central Otago. New Zealand Energy Research and Development Committee Publication P104: Volume one, Volume 2.

Pole, M.S., 1993. Early Miocene flora of the Manuherikia Group, New Zealand. 6. Lauraceae. Journal of the Royal Society of New Zealand 23, 303-312.

Self portrait of Kcenia Nechitailo, State Russian Museum in St Petersburg,
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St Petersburg – 200 years of Russian Chick Selfies

Women, so I’ve read (and seem to observe), are significantly more likely to take ‘selfies’ than men. It doesn’t seem to matter where I go now, but there are crowds, struggling under the weight of a selfie-stick, with some digital apparatus on the end of it.

In a previous incarnation, I was a photographer. This was back in the days when, after the fun part, I disappeared into a dark room, banged the ends of ten rolls of film, threaded each onto a reel, whacked them into two tanks with chemicals, and then started shaking them – five rolls in each hand.  From strips of negatives proof-sheets were printed, then some frames enlarged onto prints. If there were dust spots, sorry, I mean, when there were dust spots, I mixed up a little white paint and Indian ink to get the right shade of grey to paint them out. God – where did all that go?!

Digital has somehow profaned the whole thing. Not just photography itself, but it’s made it so much easier to turn the camera around. Framing and focusing was damned hard  on yourself. Selfies are just too-easy. But there was the time, and still is the medium, when how you presented yourself to posterity, took time and effort.

In the  State Russian Museum in St Petersburg,  I was lucky enough to come across an entire exhibition of self-portraits. Not digital, or photographs at all, but mostly paintings. The exhibition was called (it’s over now)  ‘My own self’.

Right near the entry was one of the oldest self-portraits. A picture of Ekaterina Chikacheva, painted in 1812, the same year as her untimely death, at about 25.

Self portrait of Ekaterina Chikacheva , 1812, State Russian Museum in St Petersburg,

Self portrait of Ekaterina Chikacheva, 1812, State Russian Museum in St Petersburg,

From there on, I wandered through several rooms, engrossed in dozens and dozens of self portraits. They probably covered every decade for more than two centuries. There were more than 200 self portraits in the exhibition – possibly one of the largest collection of painted selfies on the planet. Men, men, men – where were the women? I had to look hard – maybe six artists?  The male:female ratio must have been at least 40:1.

The exhibition of Self-Portraits 'My Own Self' at the State Russian Museum in St Petersburg,

The exhibition of Self-Portraits ‘My Own Self’ at the State Russian Museum in St Petersburg,

As time and the exhibition progressed, there did seem to be a few more women. And perhaps to make up for the few female artists, there were several works shown from some of them. For ex example several self-portraits of the wonderful Zinaida Serebriakova. The first in the series spanning 46 years was a pencil sketch,  drawn in about 1900, when she was just 17. The next was a painting from 1911.

Self portrait of , State Russian Museum in St Petersburg,

Self portrait of Zinaida Serebriakova, c. 1900, State Russian Museum in St Petersburg,

 

Self portrait of , State Russian Museum in St Petersburg,

Self portrait of Zinaida Serebriakova, 1911, State Russian Museum in St Petersburg,

Self portrait of Zinaida Serebriakova, 1946, State Russian Museum in St Petersburg,

Self portrait of Zinaida Serebriakova, 1946, State Russian Museum in St Petersburg,

There were also a couple from Valentina Markova, and one of my favourites – a selfie of the contemporary painter Kcenia Nechitailo, which I’ve used as the featured image.

Self portrait of Valentina Markova, c. 1930, State Russian Museum in St Petersburg,

Self portrait of Valentina Markova, c. 1930, State Russian Museum in St Petersburg,

Perhaps there is a simple explanation for the very few women in a huge exhibition of self-portraits – maybe women just didn’t have the same opportunities to paint as men. Overall, I guess not. But, I’m not sure that’s the answer. One of the few options for women of leisure, was painting. So did they tend not to paint themselves in the past? Or is the imbalance something to do with curation?

In any case – what a change! Digital media is one of the great equalisers. The massive difference in gender balance with digital selfies seems to show us a kind of underlying reality –  what people like to do, when they can….

Thoughts?

 

Mongolia- on top of a mountain, one vehicle stuck in snow, the other with engine issues.
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In Mongolia any fool can drive, but…

In five years or so  in and out of Mongolia, I’ve criss-crossed thousands of kilometres by 4WD Landcruiser. But I’ve only taken the wheel once, and that was for a short hop back to a village when my driver wasn’t well.

Let me explain. Technically, anyone can take the wheels of a 4WD and go through the motions – and say “Hey – I’m 4WDriving in Mongolia”. It’s when things go wrong that count. Mongolia is a big, big, largely empty country. And when things go wrong, you’re pretty much on your own, and quite possibly with some severe weather coming your way. Quite aside from everyone having their job, driving is about responsibility. Just like “you break it, you own it”, being a real driver means that if things go wrong on your watch – its up to you to get out. I simply knew that getting behind the wheel in Mongolia, I could’t fulfill that condition.

Our fully-laden Russian Jeep, about to make a routine crossing of a river. But rivers always change - will this time be like the last?

Our fully-laden Russian Jeep, about to make a routine crossing of a river. But rivers always change – will this time be like the last?

Take getting a puncture. You can change a wheel? Cool. We normally travel with two spares on the roof. As soon as one goes down, we think about where the nearest town/village is that can replace it. And punctures happen in the damnedest of places. You can spend hours negotiating bare rock in the mountains, and finally find yourself on a smooth, sandy track on a plain. Get out to have a pee, and that ‘pssssss’ sound is not you or one of your mates, but the bloody tire. Time and time again. But on one trip we had six punctures. Do the maths – real drivers can patch a Landcruiser tube on the fly.

Travelling in Mongolia - and another flat.

Travelling in Mongolia – and another flat.

Then there was the morning I was out in the desert, with just my driver. I set off on foot to do some geology, and sauntered back mid-morning for a coffee. I got around the other side of the Landcruiser, and there was the entire wheel/hub assembly in pieces out in the sand. “Little problem” said my driver. There was a problem he had recognised, not fatal, but he didn’t blanch from putting his head down to deal with it. In Mongolia, real drivers are self-reliant mechanics.

Repairing Landcruiser wheel assembly in Mongolia.

“Little problem”. Repairing Landcruiser wheel assembly in Mongolia.

In Mongolia you rely on your drivers for everything. They get you there. Outside of the cities there are just a couple of sealed roads. Beyond that it can be anything from graded track, to wheel ruts, or nothing. The driver typically navigates by dead-reckoning (not always without the odd embarrassing cock-up), either by being used to the general route, or perhaps because he came this way once five years ago. Real drivers seem too have an amazing map inside their heads.

In Mongolia, travel across the wide valleys is often tricky. You can be bogged in a flash, and unlike anywhere else , tall grass can hide the danger.

In Mongolia, travel across the wide valleys is often tricky. You can be bogged in a flash, and unlike anywhere else , tall grass can hide the danger.

Partly it’s knowing the landscape. After a while you can look into the Mongolian countryside and predict where the tracks are going to be. Typically the centers of the plains are avoided. This is where the finest mud accumulates during floods, and it’s where you risk sinking. The huge gravel fans have dozens of deep channels in them. You either want to be well above them, right up in them, or be in that narrow zone between where they hit the plain, an the mud. But sometimes you have no warning and stuff happens. In Mongolia its always a great idea to travel in a pair of vehicles. One can help the other one out. Real drivers know when to toss the ego and work as a team.

In Mongolia, sometimes your only hope is another vehicle. Bogged to the floorboards, nothing to tie your winch to, screwed without some help.

In Mongolia, sometimes your only hope is another vehicle. Bogged to the floorboards, nothing to tie your winch to, screwed without some help.

A real driver can read the signs. A pair of wheel ruts going into a mountain gorge is a good sign you can get through. If its’s only a single rut – a motorbike trail, it’s a good assumption you can’t do it, because no one else has.

Two wheel ruts go into this Mongolian gorge - so there is a good chance we can get all the way through.

Two wheel ruts go into this Mongolian gorge – so there is a good chance we can get all the way through.

But hey, you can always be the first! A good, confident driver, will give it a go – or tell you if it’s a stupid idea.

In Mongolia single wheel ruts are made by motorbikes, and typically mean bad news for a 4WD. But no-one says you can't try!

In Mongolia single wheel ruts are made by motorbikes, and typically mean bad news for a 4WD. But no-one says you can’t try!

Winters are just too harsh to work in Mongolia – but spring can be a difficult time too. There are still deep, soft snow-drifts here and there and sometimes you just have to try and cross them. And frozen rivers that were perfectly safe to cross a week ago – are they safe now. These are decisions real drivers have to make. If they get stuck – it’s their responsibility to get out.

Mongolia - stuck in a snow drift.

Mongolia – stuck in a snow drift.

Mongolia - spring, when that frozen river starts to thaw...

Mongolia – spring, when that frozen river starts to thaw…

And real drivers too, are about personality. You constantly come across ‘incidents’in Mongolia  – a car crash, a truck off the road, a family vehicle stuck in a river, or, as on several occasions, a family sitting in a lone vehicle in the middle of no-where, out of petrol – and out of water. A good-natured driver will take any of this in his stride, stop, and do what he can to help. We’ve quickly  pulled several vehicles out of trouble. We never gave away petrol, but checked on the occupants of stranded cars and gave water if needed. Once we operated as the ‘Delgerengui Schoolbus’. My driver explained that the kids from the local nomad families spend the week at school, only coming home for the weekends. We picked them up and drove them to school one Sunday.

Mongolia - the 'Delgerengui Schoolbus'. The back seat of our Landcruiser taking a bunch of kids, and some parents, to school.

Mongolia – the ‘Delgerengui Schoolbus’. The back seat of our Landcruiser taking a bunch of kids, and some parents, to school.

Drivers often double as cooks – something I just can’t do. At least when it comes to whipping up something nice in the middle of no-where. They might even know how to boil water using crap. And of course, real drivers are good company – you are with them for long, long trips.

In Mongolia, real drivers are good company.

In Mongolia, real drivers are good company.

In Mongolia, real drivers can teach you tricks about surviving in the desert...

In Mongolia, real drivers can teach you tricks about surviving in the desert…

So you see, in Mongolia, anyone can drive, but it takes pretty special sorts to be real drivers….

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The Log Cabin at the Heart of St Petersburg, Russia

The most famous ‘little log cabin in the woods’ is probably the one in which Abraham Lincoln grew up in Kentucky. It was built in 1808, but unfortunately, no longer exists.  However, in St Petersburg, Russia, there is to this day, a log cabin built in 1703. It was the home for a few years of Tsar Peter the Great – the man who founded St Petersburg.

Peter the Great's original log cabin on display to the public, in St Petersburg.

Peter the Great’s original log cabin, virtually the first building of the city, on display to the public, in St Petersburg.

At the time, the area was mostly still one vast swamp or bog, although a map from 1698 (when the place belonged to Sweden) shows scattered houses and what appear to be ploughed fields.

A map of the St Petersburg area in 1698 (above) showing green forests and swamps and a few buildings and apparent plouged fields. Below I have superimposed a Google Earth image of St Petersburg as it is toda

A map of the St Petersburg area in 1698 (above) showing green forests and swamps and a few buildings and apparent ploughed fields. Below I have superimposed a Google Earth image of St Petersburg as it is today. A red arrow indicates the location of Peter the Great’s log cabin.

Peter decided he wanted a new capital (he wasn’t a fan of Moscow) and one that had good access to the sea. He chose this spot on the River Neva, and despite all the trees and very high water table, said something like “делай!” (Do it!). And St Petersburg was built. In the meantime, he lived in his little log cabin, presumably built from trees growing on-site.

The end of one of the logs making up Peter the Great's log cabin in St Petersburg. The narrow growth rings indicate the short growing season in this region of very harsh winters.

The end of one of the logs making up Peter the Great’s log cabin in St Petersburg. The narrow growth rings indicate the short growing season in this region of very harsh winters.

The log cabin remained – Peter was proud of his frugal ways (other than building cities) and to preserve it, it was encased inside a small brick building in 1723. This is open to the public as a museum.

View from the south bank of the Neva across to where Peter the Great's original log cabin is now behind some trees (red arrow).

View from the south bank of the Neva across to where Peter the Great’s original log cabin is now behind some trees (red arrow).

I’m fascinated by old images and trying to line them up with the present-day view. The Cabin museum displays a couple of old views of the building, one from 1805 and another of about the same age. These confused me, as they show a building much closer to the river than the present day. There is also a model reconstructing what I take to be the cabin and its immediate surrounds as they were in 1706. Neither buildings in the model match what is now inside the brick enclosure, but they still seem to be close to the river. During my visit, I looked at the two images and the model, and I wondered if the cabin once lay a little bit to the west. closer to the Peter and Paul fortress. This has a little bridge over to the island, which might be what is shown in the model.

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1805 image of the brick building built in 1723 enclosing Peter the Greats cabin. Note the river very nearby to the left. Source: Photographed in the Peter the Great Cabin Museum, St Petersburg

 

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A further image of the brick enclosure around Peter the Greats cabin. Probably around 1805. Note the nearby river. Source: Photographed in the Peter the Great Cabin Museum, St Petersburg.

 

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Model in the Peter the Great Cabin Museum, presumably showing the cabin in 1706. But is that bridge over the Fontanka River, or the Kronversky Protok? Source: Photographed in the Peter the Great Cabin Museum, St Petersburg.

That the cabin had been moved at all was something I don’t think was pointed out in the museum. At least in English. However, I later read in Wikipedia that the cabin was relocated to its present site “in 1711 from its original site on the north bank of the River Neva close to the present Winter Palace“. This is a little confusing, as that would surely be the south bank. Perhaps that is just a typo, but it doesn’t help with the image from 1805 looking closer to the river.

A map from 1705  does show some buildings near the Fontanka River meets the southern edge of the Neva, and a bridge. Perhaps this is the original location of the cabin? If anyone knows, do tell.

A 1705 map of St Petersburg. Was Peter the Greats log cabin once at the location shown by the red arrow? Its present location is shown by the blue arrow.

A 1705 map of St Petersburg. Was Peter the Greats log cabin once at the location shown by the red arrow? Its present location is shown by the blue arrow.

Whatever. The original little cabin in the swampforest, basically the first building of St Petersburg. It’s still there….

Miocene Nothofagus leaf and Allocasuarina fruits, New Zealand.
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Miocene Rain and Fire Forests of Bannockburn

Canungra is the perfect place to stop for a snack on the drive up to O’Reilly’s/Lamington National Park in southeastern Queensland. On a weekend you can grab a latte and pie and sit outside a cafe, watching the biker crowd doing pretty much the same thing. From there you start winding your way up the one-way road, up the flanks of an extinct Miocene volcano, up towards the extinct caldera that forms the border with New South Wales. As you get higher, the temperature drops and the annual rainfall goes up.

Low-down the vegetation is typical Australian Eucalyptus and casuarina-dominated ‘fire-forest’, which will burn every few years. But then there are distinct and sharp boundaries, where you suddenly go from open fire-forest to a much more closed, shady and clearly more diverse forest. These are the rainforests, and the boundaries are from fires – the rainforests don’t burn.

Sunset from O'Reilly's. Canungra is down and off to the right.

Sunset from O’Reilly’s. Canungra is down and off to the right.

Between 1999 and 2007,  I taught ecology classes in the O’Reilly’s rainforest, With spending so much time up there, I finally reached the point where I could immediately identify 111 species of rainforest tree or vine – and I started feeling slightly respectable. But these feelings were always put into perspective with a memory from a decade before.

I was on a field trip in 1988 and had the pleasure of meeting botanist Geoff Tracey in the far North Queensland town of Yungaburra. Geof blew me away with his encyclopedic knowledge of tropical rainforests. He could pull leaves off trees and hand them to me with their names, faster than I could write them all down. When I asked him how many species he could rattle off the names for, it was over 2,000.

Geof and his colleague Len Webb (who I’ve never met), were an academic partnership that made a significant impact on understanding Australian rainforests. Among their publications, one with Webb as sole author (Webb 1959) presented a classification of Australian rainforests that remains in common use today. It’s efficacy is through using ‘physiognomic’ and ‘structural’ characters but just a minimum of botanical names. Being able to recognise rainforest types consistently was a big step towards understanding them and the underlying climate and geological conditions that caused them.

Webb called classified warmer rainforests* as ‘vine forests’, in recognition that they typically containing robust lianes. The cooler forests with only wiry vines, he called ‘fern’ or ‘mossy’ forests.  Further subdivision was based on the most common leaf size – for instance ‘Notophyll’ for leaves between about 8 and 13 cm long. This is a common leaf size in rainforests living under a broadly subtropical climate. Cooler than that, the leaves are smaller, warmer and they are larger. One of the few floristic terms he regarded as important was the presence of either hoop or bunya pines (genus Araucaria)

Part of my PhD on New Zealand plant fossils was based near the village of Bannockburn. Strata of the Miocene Manuherikia Group there have been tilted up on an angle, and leaf fossils are common in various layers. One of the key findings from this work was that there were several quite distinct assemblages of fossil leaves and fruits – each representing a different original vegetation types. This is actually not so common – most Miocene plant fossil assemblages from elsewhere around the world seem to represent just one kind of vegetation. The variety seen at Bannockburn is somewhat unique.

Webb and Tracey’s works were a big influence on me – and gave me a conceptual framework into which to place the Miocene plant fossils at Bannockburn. Most of Webb’s criteria are not visible in fossils, but I thought enough of the important ones were, or could be inferred, to suggest some of Webb’s forest types.

Miocene Eucalyptus fossil New Zealand

Miocene Eucalyptus fossil New Zealand

The presence of both Eucalyptus fossils in New Zealand and casuarina fossils in some layers at Bannockburn indicates fire, analogous to the lower parts of the drive from Canungra up to O’Reilly’s. However, they are mixed in with more typical rainforest leaves – and suggest a vegetation mixture, such as ‘wet sclerophyll  – rainforest regenerating through fire forest in the long absence of burning (see the featured image of a Nothofagus leaf next to a casuarina fruit).

Miocene hoop pine (Araucaria) fossil, Bannockburn, New Zealaand

Miocene hoop pine (Araucaria) fossil, Bannockburn, New Zealaand

Hoop pine fossils in New Zealand are present in one zone. This suggests Webb’s ‘Araucarian Notophyll Vine Forest’. This is broadly equivalent to what some authors call ‘Dry Rainforest’. It’s oxymoronic, but it means a forest which is relatively dry, but still excludes fire. This (along with the Eucalyptus and casuarinas) suggests periodic relatively dry conditions at Bannockburn. However, in detail, the associated leaves are smaller than notophyll, suggesting cooler conditions than typical ‘Araucarian Notophyll Vine Forest’. Dry rainforest with hoop pines is the first rainforest one encounters on the drive up from Canungra.

Large (120 mm long) Miocene leaf fossil, Bannockburn, New Zealand.

Large (120 mm long) Miocene leaf fossil, Bannockburn, New Zealand.

One layer at Bannockburn has relatively large fossil leaves, without any Nothofagus or Araucaria. This suggests the warmest conditions in the section, and without any marked dry seasons. This corresponds to Webb’s Notophylll Vine Forest, and is analogous to forest above O’Reillly’s.

Nothofagus leaf fossils are only found in the lower part of the Bannockburn section – suggesting this had  the coolest conditions, analogous to the Caldera Rim at Lamington National Park. Higher up,

There is also a zone at Bannockburn dominated by palm fossils. This is probably indicating soil conditions at least as much as climate. The fossil vegetation will have been roughly similar to Webb’s Mesophyll Palm Forest, type, just significantly cooler. There are an palm swamps on the drive up from Canungra simply because there are no flat areas of waterlogged soil. Palm swamps are present on the coast to the east.

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The Miocene section at Bannockburn, New Zealand, with location of key plant fossils and corresponding vegetation types shown.

Getting back to Australia, as you head up towards the state border from Canungra, you can see four basic types of forest in a rise of a several hundred maters. From fire forest you enter dry rainforest, then subtropical rainforest, and above O’Reillys there are patches of warm and cool temperate rainforest, In those Miocene rocks at Bannockburn, you can see at several very distinct fossil plant assemblages in about 80 m of geological section. That’s special. This suggests the present climate of Canungra is a good place to start when thinking of the temperature of southern New Zealand in the Miocene.

Canungra is about 100 m above sea level, and has a balmy average annual temperature of around 19 C – far warmer than the 10 C or so of southern New Zealand where Bannockburn is.  Average temperature drops at around 0.6 C for every 100 m increase in altitude. O’Reilly’s is at about 920 m above sea level, and thus has a average temperature of about 14 C, while the Caldera Rim/state border is about 1160 m and will have a temperature of a little less than 13 C.

Thus, the warmest rainforest at Bannockburn may have grown under something less than 19 C, while for the coolest ones it could ranged down to at least 13 C. The range of fossil vegetation types seen at Bannockburn was clearly not a result of changing altitude. All the sediment was formed in low-lying, swampy conditions close to sea level. Rather, they suggest broad changes in regional climate – enough to tip the balance between fire-forest and a range of rainforest types.

Getting back to Canungra again, 19 C will do me just fine – perfect for sitting outside a cafe with that latte and a pie…

*Following Baur (1968) and various current authorities (see Bowman 2000), I use the term ‘rainforest’ rather than the ‘rain forest’ that Webb used. This format tends to de-emphasise both rain and that it needs to be a forest (It’s more about absence of fire and light conditions).

References (Clickable links to download a pdf)

Baur, G.N., 1968. The ecological basis of rainforest management. Government Printer, Sydney.

Bowman, D.M.J.S., 2000. Australian rainforests : islands of green in a land of fire. Cambridge University Press, Cambridge, England.

Pole, M. S. 1993: Early Miocene flora of the Manuherikia Group, New Zealand. 10. Paleoecology and stratigraphy. Journal of the Royal Society of New Zealand 23: 393-426.

Webb, L.J. (1959) A Physiognomic Classification of Australian Rain Forests. The Journal of Ecology, 47, 551-570. You can get a pdf of this paper here. Webb’s paper is Number 34 in a list of 100 influential papers. Click on the pdf link adjacent the number 34.