Tag Archives: Geology

On our last leg(s) – the journey to Christchurch

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Sunday 22 March 2026 – Dunedin was our last stop on the tour of the South Island. All we had to do was to get ourselves to Christchurch and hold ourselves in readiness for our return flights to the UK. Because of the unpleasantness in the Middle East, our original journey back via Dubai had been changed so that our route was now (a) via Singapore and (b) a day later. Thus we would have two nights and one day in Christchurch, and a layover in Singapore’s Changi airport of some six hours: total journey time therefore 30 hours, including 24 hours in the air.

But first we had to get ourselves to Christchurch, a distance of some 360km. Despite Jane’s best research efforts, there wasn’t a whole host of things to do and see en route, but she did find a couple of interesting diversions on our journey.

The first of these was still just about within the Dunedin city limits – Baldwin Street, dubbed the World’s Steepest (driveable) Street.

It’s notoriously difficult to convey steepness, either up or down, in photographs, so I made the sacrifice of walking up the steepest bit so that I could bring you a dispassionate measurement of the gradient.

It’s not that steep the whole way; a section near the top is the steepest.

I walked up the road, but Jane took advantage of steps, which run up one side of the steep bit.

For fun, we did another way of conveying the gradient.

At the top is a seat, much needed by some of the folk that had got that far

and some info about the street

Of course, some people have to make getting up the street a real challenge, and there are a couple of plaques there which are nods to the “because it’s there” lunatic tendency of some people.

and there’s one rather charming record, by the water fountain there, of a successful attempt to climb the street by a young lad aged only 3 years and 4 months.

After that little workout, we moved on, leaving logging country for more pastoral landscapes.

There were some exceptions to the low-rise nature of the landscape; Jane took this photo as we refuelled near a town called Bushey.

The Glastonbury Tor lookalike at the top is the Sir John McKenzie memorial, by the way (he was a politician in the last half of the 19th century). The last two thirds of the journey is through pancake-flat landscapes, which are conducive to high-density cattle farming, something we had noted in a few other parts of the country.

As we followed the coast northwards, we reached a town called Moeraki. It shares a name with Lake Moeraki, but the connection is merely linguistic, if ChatGPT is to be believed; Both names come from the word “moeraki” in the Māori language, often interpreted as something like “sleepy sky” or “day of rest”. Anyway, this Moeraki is a beachside town and on the beach are some geologically very interesting objects: the Moeraki Boulders.

Although their formation is a matter of abstruse geology, it’s clear that they are a popular tourist attraction. They are “septarian concretions”. A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, found in sedimentary rock or soil. Septarian concretions are carbonate-rich concretions containing angular cavities or cracks (from the Latin septum, “partition”, referring to the cracks or cavities separating polygonal blocks of hardened material). Some of the boulders show this partitioning very clearly, indeed looking as if someone has taken a broken one and glued it back together.

There are some broken boulders on the beach, which also give an idea of the crystalline nature of the material between the compacted mudstone.

There are many intact boulders, most of them part-buried within the sand

and very popular for kids to play on and (sigh) selfies. There’s one which looks to have rolled off the cliff where it was formed relatively recently (in geological terms, anyway).

Human provided for scale

The boulders are spherical through the way they were created, over a period of some 65 million years and starting with a seed, which might have been a shell fragment. Mineral-rich water percolating through the mud deposited crystalline material and mudstone evenly so that it expanded spherically within the cliff it was building up in.  When the cliff is eroded away by the sea, the formed boulders then roll down to the beach. There are apparently other similar phenomena on the North Island as well as these here.

We might have then completed the journey to Christchurch with no further stops other than for coffee, for example at this accurately-named establishment

which had a very enticing array of cakes.

But Jane noticed that a place called Geraldine had a vintage motors and machinery museum.  I was taken enough with the name of the town, as well as with Herbert and Alma along the route; but the prospect of a vintage museum proved irresistible, so we stopped off to take a look.

The desk was manned by a volunteer called Bruce, who was very pleased to see us, and accompanied us as we went into the first of the halls, which was real veteran cars.

It turned out that he owned one of them

but was also anxious to tell us about many of the other ones, too.  He was a lovely chap, but we were quite glad when other customers came along and diverted his attention away from explaining all the cars there. There were some interesting exhibits, such as this Model T Ford

and this creation, which I’d never come across before, the Reselco Solocar.

We wandered around the other sheds: tractors,

with a very charming array of tractor seats along one wall

and some very elderly-looking examples;

Stationary engines;

Crawler tractors;

and models.

There were other sheds with various other sorts of machinery, such as lawnmowers, much incidental period stuff such as old cameras and household goods, and a model horse in the yard.

The last shed contained cars of a vintage that was much more my period

Vanden Plas Princess 3-litre R
Wolseley 6/99
Armstrong Siddeley
Vauxhall Veloxes

and a Jag I’d never come across before, an XJ40 (mislabelled as a JX40, I might add).

The place had the same amateur air as Brooklands Museum used to have before it got really popular; amateur in the good sense of love being lavished on the exhibits.

There were a couple of quirky roadside objects to be spotted en route – creative use of hay bale “marshmallows”

and, having passed Bushey (the name of a town near where I was born), we also passed Chertsey

a town near where we now live. But there wasn’t another roadside attraction to divert us and so we found ourselves at the Sudima Hotel in Christchurch, not far from the George where we’d stayed before (and would have again, had they had room for us). It wasn’t the Small Luxury Hotel that the George is, but it was a well-organised and comfortable room and the service was friendly and efficient.

During our free day in Christchurch, apart from writing this blog, my main task was to return the hire car. This had the potential to be complicated, as I had agreed, on taking on the car at Greymouth all those weeks ago, to return it to the airport rather than the city depot of the car hire firm. Our travel agent hadn’t managed to change the arrangement, and I couldn’t persuade the agent on the phone to Budget that I even had one of their cars, far less could make any change to its return location. So I drove it, via a refuelling stop, to the Budget city offices to discuss whether it was OK to just drop it off there. To start with, that was a very frustrating process because there was only one chap on the desk actually helping customers, but, for some reason, a couple of others drifting about Doing Mysterious Things that didn’t help at all reduce the queue of three people in front of me. The chap at the desk was being frightfully helpful to an elderly American couple who seemed to be having many troubles picking up a car; he even spent time explaining phone charging cables to the lady and helped her buy one from the machine on the premises. All this took about 20 minutes with the three guys in the queue and me exchanging ever more meaningful looks and raised eyebrows. I had just resigned myself to a long wait when a guy wandered in to the office with a key for a car he was returning and said “fuelled up, no damage; can I just leave the key here?” and the desk chap just nodded. So I followed this wonderful example, and got the nod from the desk chap that the airport/city dichotomy was not a problem, dropped the key off and hightailed it back to the hotel before they could change their mind. I haven’t received any credit card charge, so I am currently assuming that all is OK.

We treated ourselves to one more Decent Cocktail And Nice Meal at the George in the late afternoon, after which, to shake the food down, we went for a walk. Obviously. So we got a few more photos of Christchurch’s street art,

cafés,

handsome buildings;

Antarctic Heritage Trust HQ

scenes of riparian beauty,

and even a farewell wave from Robert Falcon Scott

before turning in for the night to get some sleep before the long journey home.

So, that was it for New Zealand. We’ve had a wonderful time, full of new experiences, sights and sounds; we’ve covered over 3,700km on largely uncrowded roads; and we’ve walked over 200km, including a couple of toughish hikes. The country is a delight for British tourists – well-organised for a wide variety of activities at a wide variety of accommodation types and it’s been a pleasure to be able to enjoy much of that variety. Slightly sadly, we head home; there will be no more entries on these pages for New Zealand. But fear not: we will be on the road again in about six weeks’ time and I hope to be able to bring you the exciting sights of our next trip here. Where are we going? Ah – you’ll have to keep in touch with these pages to find that out.

 

 

 

Day 5 – Not as originally planned

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Wednesday 3 September 2025 – Mother Nature played a few games with Kuba’s plans today. The idea had been to do a landing and walk to a glacier. This one, actually,

but keen eyes on the bridge had spotted a polar bear nearby.

Yes, there really is a polar bear in this picture, which gives a good idea of how keen are the eyes of the crew. Here’s a closer view.

This meant that we couldn’t land, mainly for the polar bear’s benefit, since it would have been shot if it had started to make a nuisance of itself.  So we cruised around in Zodiacs instead. On the shores of the fjord, which is called Wijderfjord (I’ll let you guess why) there was an abandoned trapper’s cabin from the days when that sort of thing was permitted.

There was plenty of bird life to be seen – the ubiquitous kittiwakes and other gulls, who found the various islets very convenient scouting posts for any possible picking on other species they could consider.

On the shore line, we saw a gang of purple sandpipers fossicking around and feasting on the region’s delicious seaweed.

There were arctic terns flitting about,

and every so often coming over to check us out.

The geology was fascinating: close-to, layers of different coloured rock made some lovely patterns;

and, far-off, we had some wonderful landscapes.

Specifically, there was a canyon for us to explore.

This river flows from Five Mile Lake; but we could only go a short distance up because there was quite a considerable current flowing out of it into the fjord. You can see what looks like rapids further up the stream in this picture.

Having cruised the canyon, we then made a landing, which I hadn’t expected,

and took a short, but somewhat exhilarating hike

up to a viewpoint,

where we got a different perspective over the canyon

and the wonderful scenery.

Kuba (left) and Gunnar are the guides that drive the Zodiacs and lead the excursions.

They are both armed and dangerous, mainly to any importunate polar bears.

On the hike, we saw some interestingly split rocks,

and some of the local vegetation.

Then we headed back to the ship.

Kuba explained that his original plan had been to do the canyon and associated landing in the afternoon, with a somewhat longer hike to Five Mile Lake.  But it wasn’t that far from where we couldn’t land earlier because of the polar bear; the bear could easily have covered the distance to the second site during the morning, so we couldn’t risk an afternoon hike there, hence the abbreviated morning walk.

Instead, for the afternoon, we moved around the corner into Woodfjorden and did a landing at Jakobsenbukta. Again, the scenery was awesome.

The shore was basically a glacier river delta, with lots of water (and driftwood).

The weather was incredibly mild, possibly as warm as 8°C, so most of us were wearing (relatively) light clothing and carrying very little.  The exception was Doina and Denis, who live and breathe (and make a living from) online content, so they were fully kitted up.

The site was not one that Kuba or Gunnar had ever visited before – they had taken a look at maps and decided that it looked promising for a short hike; having landed, they then discussed which direction we should go.

The direction they chose wasn’t a problem for most of us; we’d followed instructions to wear our rubber boots. Not everyone had, though, so there was a bit of a hold-up whilst people worked out how to cross a water-filled channel – not deeper than wellie boots, but deeper than hiking shoes!

The delta had areas of still, calm water, which made it a fantastic source of my favourite kind of image – reflections!

The view back to the ship was quite impressive, too.

Jane spotted a footprint,

which we assume came from a reindeer, as did a small pile of droppings we passed. We also passed some Campion moss

which has evolved a survival defence against being eaten by reindeer, which is one of the few animals which can digest normal moss. Thus, it being slow-growing, this clump could be quite old. (Campion, The Wonder Moss?) We were enjoined to take care and avoid walking on it and others like it.

Our walk took us towards the near ridge you can see below, with Kuba leading and Gunnar behind (so he was the rear Gunnar at this point).

However, Rolf’s footwear developed a technical problem

and so Kuba and Gunnar had another planning session and decided to split the party. Kuba led a few of the party, including Rolf, obvs, back to the landing site, where (I think he had to spill the beans on a surprise, here) they could help the ship’s crew, who were planning a bonfire.  Gunnar took charge of the rest of us and we walked on to the ridge. It’s important for the man with the gun to go first in order to be able to protect the rest of the group if need be, so Gunnar was now our forward Gunnar.

We got to the top of the ridge, which gave us a chance to take in the fantastic scenery. Kuba had explained that the triangular rock was caused (as can clearly be seen here) by two converging glacier flows.  Geologists call this shape a “horn”

and I guess the most familiar to Europeans is the Matterhorn. The other famous one is Artesonraju in Peru. You may never have heard of it (I hadn’t), but you’d recognise it as the mountain which inspired the Paramount logo. To the left of the horn above is a cirque – a circular ice field with a glacier emerging from it.  The light was great for landscape photography.

After some moments for people to take in the view

we headed back down the way we came.  Agnese, the other Italian lass, found a fossil

which Gunnar told us was strictly not to be taken away from the scene. Apparently there is a chance that baggage will be scanned to check for illicit stone or fossil removal, with fines as a penalty, so no-one took the risk. No, they didn’t. Really, officer.

We could smell the bonfire before we could see it, and then there it was,

brilliantly setup by the ship’s crew, who were doing the environment a favour by consuming some of that driftwood.

Someone had even had the idea of using driftwood to create a bridge over that awkward water-filled channel.

Everything was beautifully set up, with Anni manning the bar

 

so quite quickly we had a relaxed, party vibe going on the beach.

Russell the Viking, together with Chief Officer Morten and AB Rasmus

Gunnar and AB Malte doing competitive seesaw

Proof that two females are the equal of one male?

The evening sun gave us a marvellous backdrop.

Once back on the boat, we had yet another splendid dinner from Roger, our Swedish chef (but no muppet, he), who had cooked fish that had been caught from the boat the previous evening. And timing allowed another fishing session for those who wished to join in.

As backdrop for this, we had a rainbow

and a fabulous sunset

which I think made a fittingly splendid end to another splendid day. It may not have been as originally planned, but Kuba and the skipper between them hatched up a good plan B (and then C) so that everyone had a great day.

Kuba has a plan for the morrow, too, of course – he always has a plan. Let’s see whether circumstances allow it to proceed in its original form, eh?

Coober Pedy – Life Underground

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Monday 26 August 2024 – Today was our last full day on the Ghan, and our final excursion, to a far away place with a strange-sounding name – Coober Pedy (pronounced “Peedy”). It was an exceedingly content-rich day; in other words this is a long post warning. I recommend you get yourself a cuppa or a glass of something stronger and settle down to read about the day.

After our stop at Alice and moving on overnight, the landscape had changed markedly.

We pulled into Manguri,

which was just a halt, really – no actual station or anything; just a gathering point so that people could hop on to the relevant coach for their chosen excursion. It was noticeable at this point that the temperature had dropped significantly now that we were moving south; it was very pleasant, in the low 20s, and a nice change from the 30+ temperatures we’d had further north.

We were booked on a general “explore Coober Pedy” tour, and I have to say I had no idea what to expect; all I knew was that it was the centre of a significant mining industry. The industry in question, or the quest which caused a lot of industry, is opals, and it’s a very significant one – Coober Pedy is estimate to produce around three-quarters of the world’s opal supply.

It turns out that mining opals is akin to gambling.  It’s not quite the same; gamblers always lose, the only winner being whichever house provides the game. In opal mining, it’s possible to win big or lose everything; apparently there’s a phenomenon called “opal fever”, where miners simply get addicted to the search for the next big opal seam. The trouble is that there’s no certain way of locating a seam of opal-bearing rock except simply to dig a hole and start looking around. It was not long after our coach set out (on a dirt road for much of the way) that we saw the first evidence of what effect this speculative hole digging actually has on the landscape.

Every single one of those heaps of rock, which are called “mullock heaps”, marks the presence of a hole that someone has dug in search of opals. They are everywhere on the landscape.

Apparently, even if nothing is found, the holes are not filled in with the mullock that’s been excavated, as this would result in unstable and unsafe terrain; so the holes just remain there, with a heap of mullock beside each one.

Some digging obviously uncovers rich seams which get expanded as they’re explored,

and some appear sufficiently promising that drills are set up to explore further

with blowers to clear the excavated dust away – drill on the left above, blower on the right,

and a blower in action above.

There are two main types of drills – small-bore ones for initial exploration, and larger-bore for creating a main hole from which tunnels can radiate out in the search for these precious mineral creations.

The process of claiming territory to mine is quite straightforward, but the manner of extracting opals is delicate and precise as opal is a fragile material; it doesn’t lend itself to industrial-scale large mining machinery, which is why the landscape is dotted with holes and heaps. Anyone can basically dig a hole anywhere for initial exploration. If such exploration yields a sufficiently good prospect of finding opal seams among the rock, then a (renewable) claim can be lodged (and paid for) for a certain area around the hole and for a certain period of time – maybe 20 metres for three months – and the person who lodged that claim puts pegs to mark the claimed area. They are then not allowed to move the pegs or to lodge another claim until the expiration of the current one, which puts a stop to people making multiple explorations. And there’s absolutely no guarantee that an exploration will find opals – it’s entirely a gamble.

The base rock in which opals form is sandstone. Water, seeping into the ground, picks up silica from the sandstone and then settles into cracks and other voids in the stone. Over millions of years, the water evaporates, leaving behind deposits of silica spheres; if these spherical silica deposits are arranged neatly in a uniform lattice arrangement, the interference and diffraction of light between the layers creates the colours which mark out a valuable opal; if irregular, then the result is called “podge” and is not particularly valuable. Extracting opal from rock requires extreme care – if an opal is cracked it loses all its value, so it is basically a manual operation, which explains why the good stones are so expensive.

The landscape this extraordinary industry produces is unique and strange.

You’ll notice that the landscape is utterly devoid of trees, which means that early settlers and miners were a tad short of the usual materials for building houses. The solution was direct and simple – to build dwellings underground. The stone is soft enough to make excavation easy, and yet firm enough not to collapse; the resulting dwellings (like cave dwellings everywhere, of course) are stable in temperature throughout the year, which is good, since outside it can be anything from below freezing up to 50°C. We got a chance to see what an underground house looked like later on in the day, but there were a few other things to look at first.

Our driver, Jason, described the terrain, as he drove us towards a particular viewpoint, as having once been seabed. Clearly, the waters had receded, and when they did, a remarkable process of erosion began, and what was seabed was worn further away in some places but not in others. This left some significant outcrops of stone which appeared to have “broken away” from the rest of the landscape. Actually, they were just remaining bits of seabed, but their appearance was such that they re called

The Breakaways. It’s an extraordinary landscape.

Having admired this amazing vista for a while, we headed back to Coober Pedy. The houses there are not all underground dwellings. Some are perfectly normal houses

and some are sort of hybrid, with some areas above ground and some below.

Underground houses are marked by ventilation shafts

which you can see sticking up above ground here – clearly, there’s a need to get fresh  air circulating around the dwelling.

It’s not just housing that has gone underground; so has worship.  The town features two underground churches.  We were taken as a group to the first one, a Serbian Orthodox church, which is built into a hillside.

Inside, one can see, by looking at the roof and walls, that it’s been created by two types of drilling machine – square and round.

It’s an attractive interior

Jane and I also visited the Catholic Church in the town.

In between visiting the two churches, we had an underground lunch

which was served up in the excavated but no longer active areas of an opal mine that was still in use.  We had a quick tour before sitting down to lunch,

where one could “noodle” (sort through loose stones in search of opals) or “pick” – chip away at the rock.

Whichever method one chose, a useful implement to have to hand was a “black light”, i.e. an ultra-violet light, whose beam illustrated the presence of opals within the rock.

This was technology not available to the original settler miners. Apparently what they did was to drill until they heard the sound of glass being broken, which meant that they’d found some kind of a seam, and then proceed by hand.

Outside the lunch location was some machinery which showed that the mine was still active.

as well as an exhibit of an old-fashioned windlass, which would once have been used to hoist up excavated rock.

The final component of the day was to visit a combined opal museum and underground dwelling.

Our time there started with a short lecture about the different sorts of opals (doublets, triplets, etc) and how they’re produced, with careful polishing to bring out the colours. Then we were shown round the underground dwelling which is part of the operation. It really is just this house, you know? but with no windows.

The first three pictures below are of a section excavated in the 1920s and inhabited by a miner; the remaining pictures are of the modern extensions!

Some people professed themselves uncomfortable with the idea of sleeping in the bedroom, which could, of course, be utterly and absolutely black and carry with it the extreme risk of barking your shins or banging your head during any nocturnal wanderings. I think it would be great, provided there was just a tiny bit of illumination.

There was, of course, a retail opportunity.

Outside, one could wander up on to what was effectively to roof of the house – you can see the ventilation shafts.

Its location gave a good view over the town of Coober Pedy.

The town’s location and unique geology have made it a great location for films where utter desolation is needed (e.g. Mad Max), to the extent that the town has erected its own version of the Hollywood sign.

Wandering about, one can see that there is merciless merchandising of the underground theme.

Sadly, we didn’t have time to get to the underground bar before we had to go back to the train. En route, Jason and the other coach drivers stopped short of the train in a location which enabled people to take a shot of its entire length,

and was, of course, the location for a feeding frenzy of selfies.

We arrived back at the correct side of the train to find that the crew had set up drinks and canapes outside

which one optimist used as the venue to propose to his girlfriend.

(She said “yes”, apparently.)

And so ended an exceedingly unusual, interesting and enjoyable day, full of strange landscapes and bizarre life choices. The morrow would see us arrive into Adelaide and the end of our journey on the Ghan, so stop by these pages to see what happened when we arrived.