New Zealand's South Island

We transitioned to the South Island and an arrival in Christchurch just two weeks after the shootings. The South Island is much different than the north with fewer people, higher mountains and one very large transform fault, the Alpine Fault.

Map showing our route across the South Island. The right lateral Alpine transform fault runs along the western side of the Southern Alps and goes offshore just north of Doubtful Sound. Originally, Moeraki and Dunedin were not on the itinerary but the bridge to the Franz Josef Glacier was washed out days before we were to arrive. Up to one meter of rain (40 inches) fell there in a 48-hour period, washing out the bridge and our plans had to change.

To say that the city was shocked at what happened would not convey the depth of it all. Things like this do not normally happen in quiet, little New Zealand. Yet, it did. I was amazed at the way the Kiwi's came together as a nation after this. The path forward seems clear to just about everyone here.

Our Tour Director had a friend in Christchurch who made a bundle of red roses for each member of our group...

...and we placed them on the heap of flowers that has been growing for two weeks. The memorial garden is nearly 1/2 a kilometer long! There was a great sense of respect while we were here. Tears were shed.

This is the statue to Robert Falcon Scott (the leader of the second group to stand at the South Pole in 1911) along the Avon River in Christchurch. The statue was toppled in the February, 2011 earthquake and has only been replaced within the last year.

Here is a photo of the same statue I took in October, 1986 on my first trip to New Zealand. All of the buildings in the background were destroyed in the earthquake and are no longer there.

Christchurch is looking to the future. It was once the "Most British City" outside of England. But no longer. The earthquake leveled many buildings downtown and there are being replaced with more modern-looking, earthquake resistant designs.

Map showing the epicenters and location of aftershocks from a series of earthquake events near Christchurch between September, 2010 and December, 2011. The red dotted line below the Sept. 2010 date shows the blind fault (previously unrecognized) that ruptured transverse to the Alpine Fault. This first quake had the largest magnitude of the four major shocks, making all others (by definition) aftershocks. The February, 2011 quake was the most damaging to the Central Business District and 185 people lost their lives due to structure collapse. Note the rounded Banks Peninsula sticking out into the Pacific Ocean, a heavily eroded, late Miocene volcano between 9 and 11 million years old.

We were supposed to ride the train over the Southern Alps to Franz Josef Glacier but heavy rain closed the roads and the railroads. So we went south and passed through an interesting looking town called Oamaru, known for its limestone buildings. The limestone is quarried nearby.

Much of the town's architecture has been preserved.

And gentrified.

Savory pies are a staple in New Zealand and in this out-of-the-way shop I enjoyed a Thai Green Rice pie, absolutely the best that I had on this trip. There is a dominant sentiment that I detected in New Zealand that diversity in the population is welcomed and beneficial to the country.

Next stop down the east coast was the Moeraki Boulders. I had first heard of these strange beach rocks as a young geology student in the 1970s but this was my first visit to them.

They are technically septaria nodules (also called concretions) and formed in a 60 million year old mudstone, the Moeraki Formation.

Here is a view of me next to one nodule still in place within the mudstone in the sea cliff.

The waves from big storms have cracked some of the boulders, allowing us to see the inside structure.

The septaria (cracks) are composed of calcite that has grown in the voids.

A last look at the boulder-strewn beach and cliff behind it.

Next stop Dunedin, a town of Scottish heritage and a large university, the University of Otago.

Map showing the location of Dunedin at the head of the Otago Harbor. Note the circular nature of the peninsula - like the Banks Peninsula near Christchurch, this is a 16 to 10 million year old volcano that has been heavily eroded in the last 10 million years. See more about the Dunedin volcano here.

The old railway station is a fine example of the architecture in this city. It is made of dark basalt blocks that are framed with Oamaru Limestone.

The New Zealand Pigeon (Hemiphaga novaeseelandiae) was seen on the top of a tree as we toured the Otago Peninsula.


As we made our way toward Queenstown, we stopped at the Kawarau Bridge where the sport of bungee jumping was invented. We arrived in time to see this person take the plunge.

He really had beautiful form with a nice, swan dive off the deck and a gentle curve down to the river. I would really like to be able to do this but I know that I would chicken out on the deck. It's too close to the earth. I would jump out of an airplane (again) in a heartbeat - it's high enough up for me.

You can request to barely touch the water - they have the length of the bungee down to a science - and this guy chose to do it.

The rebound back up toward the bridge looked to be the most fun and this guy made it more than half way back up!

The big excursion out of Queenstown was a day-long trip to Doubtful Sound. This is a map showing the Fiordland National Park, encompassing 3 million acres of pristine, virgin forests and deep fjords. The Park covers all of the mountainous terrain in the center of the map. There are 14 fjords that indent the coast.

The trip includes a boat ride across the freshwater Lake Manapouri, then a bus ride over Wilmot Pass, then on another ship on Doubtful Sound. The rocks in much of the Park are Cretaceous granite and gneiss, intruded when New Zealand was still attached to the Gondwana supercontinent.

Slide from one of my lectures showing the position of the southern continents during the Jurassic. Subduction occurred where the word New Zealand is located and the subducted slab melted at depth with the granite in Fiordland forming on the continental side of New Zealand.

The clouds lifted as we passed the Southern Arm of Lake Manapouri. This was incredible as this area gets an average of one inch of rain very day - an average of 360 inches per year.

The Captain took us on a side trip up the Northern Arm to show us these dikes running through the granite. The dikes are differentially eroded with the granite softer than the dikes.

Whoa - what a day! I love these clouds. High cirrus in Fiordland!

These are better exposures of the granite.

From Wilmot Pass we obtained our first view of Doubtful Sound, named when Captain James Cook doubted that he could turn the H.M.S Endeavour around in the narrow fjord. The road we were traveling on was constructed in the 1960s when a hydroelectric scheme was installed on Lake Manapouri. Read about this interesting and controversial project here. New Zealand's first nationwide environmental controversy ensued because of the project, ending in a compromise with the scheme being completed but without raising the natural level of Lake Manapouri.

Zoom lens view of Doubtful Sound.

Not a cloud in the sky. How does one do field geology in a place covered in vegetation?

A perfectly eroded U-shaped valley in the upper end of Doubtful Sound. The amount of ice that was here just 14,000 years ago is impressive.

We made it all the way out to the mouth of Doubtful Sound and the Tasman Sea. Only 2,000 miles to Tasmania! Doubtful Sound is not technically a sound, although that is the name Captain Cook gave it. A sound is a shallow river valley that has been submerged beneath rising seas (or sinking land). When Cook sailed here, geology as a modern science was not yet invented. Neither was the definition of a fjord known to the British. A fjord is a glacially carved, sea-flooded entrant on a coastline.

These tree ferns on the shore were so damn photogenic. The vegetation in New Zealand has suffered much from the arrival humans but in Fiordland National Park Park, it is preserved. This reminded me of what the forests in Gondwana might have looked like.

Another side arm in the fjord.

This concludes my trip to New Zealand. I'll be back next year with Smithsonian Journeys.

New Zealand's Volcanic North Island

For about a week, I toured the North Island of New Zealand with ten travelers on a Smithsonian Journeys adventure called Journey Through New Zealand. The North Island is where volcanism, geysers, mud pots, and hot springs play an oversized role in shaping this very active landscape. We visited and witnessed many of the features left behind by these dynamic forces.

This is a true color satellite image of New Zealand on a relatively rare cloud-free day. Blueish Lake Taupo is clearly visible in the center of the North Island and the white spine of the snow-clad Southern Alps is also obvious on the South Island.

Zooming in on the same image to the North Island with our stops listed. I flew internationally into Auckland and traveled overland to Rotorua, Lake Taupo, Napier, and the capital at Wellington.

Auckland

A view of the Central Business District (CBD) of Auckland from across Waitemata Bay at Devonport. The view is to the southwest. Auckland was built within a basaltic volcanic field that is still active! This photo is from my trip in 2017 to New Zealand.

A slide from my lecture to the group. Basaltic volcanism began here about 250,000 years ago. This image, from Geoffrey Cox's book "Fountains of Fire" shows the landscape around Auckland before volcanism began and during the Ice Age, when sea level was about 300 feet lower than present. (The modern shoreline in Auckland can be seen as the faint dashed line). I have annotated the future CBD (shown in the photo above this) and the International Airport where I arrived. Note that the Waitemata River in the top of the diagram flows east into the Pacific Ocean (left to right), but the Manukau River flows opposite this towards the west and into the Tasman Sea.

Each yellow circle represents one of the approximately 50 scoria cones located in central Auckland (not all 50 are within this image). The city center and international airport are also shown for reference to the previous diagram. The red circle in the upper right is Rangitoto Island and it is the most recent of the volcanoes to erupt - only about 500 years ago.

This is a view of Rangitoto Island from the top of Mt. Victoria in Devonport (one of the oldest volcanoes in this field). This photo is from my trip in 2017 to New Zealand.

The formation of Rangitoto Island with Maori people watching from the future site of Auckland city. Image used from "Fountains of Fire".

Drive South

Heading south, we passed Mt. Pirongia, a late Pliocene-Pleistocene basaltic center. The various peaks show basaltic vents on the volcano, now inactive. A native forest can still be found here. New Zealand was a land of unique wildlife and flora inherited from its separation with the Gondwana supercontinent. However, the introduction of exotic mammals and other pests, begin Ning with the Maori about 800 years ago, decimated native bird populations, with about 40% of endemic species now extinct. Therefore, the New Zealand government has strict requirements for entry into the country. I once traveled on a trip here where two of my fellow companions were fined $400 US each for having mud within their lug-soled boots.

Ruakuri Cave

No, this is not the extreme vertical entrance to the cave we visited. But it is a natural opening in the limestone near the town of Waitomo, where a series of solution caves have been carved into the Te Kuiti Group. This marine limestone is dated at between 27 and 23 Ma, at a time when most of New Zealand was submerged beneath sea level.

This is the man-made entrance to the cave, which is nearly identical to the natural outcrops of the limestone.

The cavern system is extensive and has numerous speleothems (cave formations) such as stalactites, stalagmites, and curtains such this one.

The caves in New Zealand are famous for their glow worms (one is curled here in the yellow oval). These are the larval stage of a dipteran fly. Their scientific name is Arachnocampa luminosa.

The natural "glow" of the glow worms. The ISO on my camera is set at 6400 and this is a hand-held image.

This is the big room in Ruakuri Cave showing the many formation to be seen here. A river runs beneath this section of the cave and "blackwater rafting" is offered inside the cave.

Rotorua

The Pohutu geyser. (This photo is from my trip to New Zealand in 2017).

Tree ferns and the Pohutu geyser on March 25, 2019. This is a localized venting area within the much larger Rotorua caldera. The rim of the caldera can be seen in the distance through the steam.

We arrived just as the geyser began its 20-minute display of steam and fountaining.

A nearby mud pot erupts with its boiling mud. The chemistry of the thermal water is such that it dissolves some of the enclosing volcanic rock, which is rich in silica. The tiny particles of silica mix with the boiling water to create the mud. I just love boiling mud pots!

At the Te Puia park, the local Maori people share their culture and crafts with the public. We enjoyed a traditional hangi, where the food is cooked in the ground traditional style.

On the road south from Rotorua toward Lake Taupo.

Lake Taupo

The Taupo Volcanic Zone is one of the most active, land-based volcanic areas on planet Earth. Its volcanic history is revealed through the many deposits scattered across New Zealand and out to sea. New Zealand is located in a very complex tectonic setting.

First off, New Zealand is the emergent part of an 8th continent - Zealandia. The continent is outlined in the black dotted line above. Part of the continent rests upon the Pacific tectonic plate and the other is part of the Australian plate. Continental crust, rich in silica and alumina makes up the crust of all continents including Zealandia, even though 85% of its rock remains submerged beneath sea level. Zealandia was once part of the supercontinent Gondwana but broke away from Antarctica and Australia beginning about 85 Ma.

Today New Zealand sits astride the boundary between the Pacific and Australian plates. Note however, that the two islands reside are on different plates. This explains the degree of complexity in New Zealand's geology.

A north-projecting oblique view of Zealandia with cross-sections cut across both the southern and northern ends of the continent. Note how the Australian plate is being subducted beneath the Pacific plate in the south, while the opposite occurs in the north with the Pacific plate subducting beneath the Australian plate. In between these two opposing subduction zones runs the Alpine fault, a right lateral offset much like our own San Andreas fault. With two opposing subduction zones and a San Andreas-type fault, it is an understatement to say that New Zealand is geologically active.

Close-up of the Taupo Volcanic Zone showing the four large caldera complexes of Rotorua, Okataina, Maria, and Taupo, and the three stratovolcanoes of Tongariro, Ngauruhoe, and Ruapehu (New Zealand will challenge those who suffer from vowel-phobia). 26,500 years ago a tremendously large eruption from Taupo created the caldera there.

These slides are from my lecture to the group and highlight some of the enormity of this eruption, the largest on planet Earth since the Toba (Indonesia) eruption about 71,000 years ago.

The 26,500 year Taupo eruption is known as the Oruanui eruption and this illustration shows the relative amounts of material erupted in other, more well-known eruptions. About 100 cubic miles of rock was erupted. For comparison, about 1/4 of a cubic mile was erupted at Mt. St. Helens in 1980.

Lake Taupo today is a quiet, peaceful place with a small town of retirees living along it quiet shores. I would imagine that most residents know something about the lake's violent past but maybe don't want to dig too deeply into the details. For myself, I find it interesting how things change with time.

Napier

These changes can be readily understood by those who live in and visit Napier, a unique city on the North Island's Pacific shore. On February 3, 1931 the entire Central Business District (CBD) was destroyed in a 7.8 magnitude earthquake. Within two years, the CBD had rebuilt in a modern style for the day - what we call Art Deco style today. Only in the 1990s, when some of the buildings from this era were being razed for newer development did the residents realize that they had a treasure - a city entirely built when the rest of the world's economy was stagnant during the Great Depression. Now, Napier's CBD is a tourist draw. The building above highlights the specific time when the city was rebuilt. To learn more about this devastating New Zealand earthquake, see here.

This could easily be a building from the 1930s movie, Superman. The Daily Telegraph was Napier's newspaper back in the day.

Another Art Deco building in there CBD of Napier. Of course, I have many other photographs but free time is short on this trip and I cannot include as much as I would like.

Wellington

We spent the day driving south toward Wellington, New Zealand's seat of Parliament and its capital. The city is located on a beautiful bay with many long-running ridges trending southwest-northeast. This fabric is due to a splay of faults that also have historic movements resulting in tragic human casualties. The January 23, 1855 earthquake with a magnitude of 8.2-8.3 is the strongest jolt in New Zealand in historic time. A whopping 59 feet of lateral offset was documented from this one quake. It seems as if we have been traveling in New Zealand with me talking to our small group only about one devastating event after the other. Don't think for a single moment that I am not keenly aware of how this must appear to my fellow companions, who may not have the time-honed ability to separate the stupendous natural history story of these events from the resulting loss of life and property. The scale of the events here is impressive and New Zealand is a MUST visit for anyone with an interest in the natural world and especially geology.

The red cable cars climb the hills to the west.

A view to the west from Mt. Victoria toward the CBD and the harbor area. What a lovely setting and we all loved this gentile city of about 400,000 people. Note the faceted spurs on the hill in the upper right of the photo. These triangular-shaped spurs highlighted here in sunlight denote where the Wellington fault cuts across the view. This fault is one of the many strands of a fault system that runs through this area. The Wellington fault runs along the base of the hill.

Flying out of Wellington toward the west, I took this last shot of the southern end of the North Island. I will be posing about my South Island journey next.