Julian Thomson

I am a former Waldorf high school science and outdoor education teacher. In addition i was the science educator and communicator for GNS Science - New Zealand's geological research institute. I am now and independent education and science communication consultant, working with scientists and teachers. I focus on raising people's interest and engagement with the natural world.

Scientists’ response to the Canterbury Earthquake

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Whilst those of us in Wellington may have felt a short jolt and a bit of a wobble, the 7.1 magnitude earthquake hitting Christchurch on Saturday morning was an altogether different experience for the locals. People I have talked to referred to the noise of the quake as being one of the most powerful aspects of the experience. Different specialist teams from GNS Science immediately leapt into action to capture vital information about the origin and effects of the quake, and to keep authorities, public and news media updated. Web traffic has been very high with the GeoNet website receiving 15 to 20 million hits per day. This image is the seismic drum for McQueen’s Valley, near Christchurch on the Saturday afternoon. You can see how the aftershocks are very frequent. Some of them are up to magnitude 5.4, though scientists think a larger one of up to magnitude 6 is possible sometime in the next few days. This seismic drum is from the same time, but recorded in the far north up at Waipu. You can see how the weaker ground shaking has not reached that far, but many of the aftershocks are still recorded there. It is interesting to look at the way the waveforms change when they are recorded a lot further away from the epicentre. An initial flyover of the surface rupture revealed a fault trace about 22kms long in the Rolleston area to the west of Christchurch, with a maximum of 4 metres of horizontal and 1.5 metres vertical displacement. The surface rupture passed close by a few farm buildings and beneath two farm houses. The fault dislocated some hitherto undisturbed glacial river terraces, showing that it has not moved for a minimum of 16 – 18 000 years. Here is a video of the fault trace from the air: The Geonet seismologists started the analysis of the large number of aftershocks detected by the NZ network of seismometers, finding their locations and magnitudes, and using the information to interpret crustal stress and strain dynamics in the region. The data collection systems were thoroughly tested and have performed very well through this event. A team flew down to Canterbury and installed an array of extra seismometers which add further data as the aftershocks continue. Other GNS Science teams are now in the Christchurch area assessing and monitoring such things as: infrastructure damage, including water and sewage, fault and landscape mapping, risk engineering, high resolution GPS measurements, and further measurements and mapping of ground motion.

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Romanian Salt

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Another place that I visited in Transylvania was the town of Torda, where there is a huge (1200 metre thick) salt deposit that formed about 18 million years ago. The salt can be found forming the sides of a nearby valley where it has been eroded by rainwater into pinnacles. The salt is 99% pure and the crystals form cauliflower like surfaces covering large areas. It has been mined since Roman times, and some of the undergound workings have become huge chambers up to 80 metres long, 50 metres wide and 40 metres high. The high relative humidity, constant temperatures, absence of dust and high concentration of sodium chloride particles in the chambers are regarded as beneficial for sufferers of breathing disorders (eg asthma, allergies etc). Large areas are equipped with playgrounds, a restaurant, internet access and even a church so that visitors can spend days at a time underground.

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Romanian Ice Cave

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On a recent trip to Europe, I spent time in Romania, France and Italy. Here are some of the geological highlights I visited: This photo is an underground glacier in the Apuseni Park. This is an area of the Carpathian Mountains with over 200 limestone caves. The Focul Viu ice cave that we visited is one of several in Romania. There is about 25 000 cubic metres of ice which has accumulated as snowfall from a large hole in the ceiling of the cave ( along with branches and leaves from the surrounding forest). Due to the poor circulation, cold air sinks into the cave and maintains very low temperatures even in the hot summer months. An 8 metre ice core has been retrieved from this cave. A piece of wood from 7 metres down was dated at about 1700 years old.

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The Wellington Fault with LEARNZ

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LEARNZ is a unique kiwi organisation that runs ‘virtual’ field trips for primary and secondary schools in New Zealand. Using videos, audioconferences and internet based information, school kids are able to interact with scientists and other expert professionals in different parts of New Zealand. LEARNZ even runs virtual field trips to Scott Base in Antarctica. Last week, Shelley Hersey and Andrew Penny from LEARNZ were investigating the Wellington Fault. Russ van Dissen, Julia Becker and Hamish Campbell from GNS Science joined me to assist them. We looked at the way scientists work with planners and emergency services to understand the earthquake risk and prepare for the possibility of a ‘Big One’ striking Wellington. There is nothing like a detailed description of the potential impact of a natural disaster to remind you to re- check your personal Civil Defence emergency preparedness! In addition to the many other active fault lines in the region that could cause an earthquake, there is a small but real possibility of a Wellington Fault earthquake occurring. This would cause a rupture along the fault line with perhaps 5 metres of sideways movement and one or two metres of vertical dislocation. Houses built across the fault would be ripped apart, and the whole city shaken violently, resulting in severe building damage, streets full of glass and other debris, broken water, gas and electricity supplies, roads, railways and the ferry terminal out of action and communications largely cut off. Did you click on that emergency preparedness link yet? Over three days we visited a number of city viewpoints and structures, the emergency operations centre of the Wellington Regional Council, the fault line itself, and the water supply lakes at Te Marua. It was reassuring to see how much thought and effort has been put into planning for the earthquake risk by the authorities. In this photo of the place where the fault runs right below the Thorndon overbridge and the Wellington Railway, you can see the steel re-inforcement casings around the motorway support pillars and the large concrete slabs that are designed to prevent the motorway segments from collapsing. The take home message is very much that local government and other organisations are doing their bit, and it is up to us individuals to make sure that we have our personal survival plans in place as well. Over one hundred school classes participated in the event. The GNS Science website has a lot of information about the Wellington Fault, including a tour guide, a fault line field trip, a photo gallery , a Google Earth flyby video as well as our Wellington Fault short doco movie:

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Under a cloud in the UK

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Having arrived at Heathrow a few hours before the shutdown of all flights over Britain due to the volcanic eruption in Iceland, it has been fascinating to watch the unfolding impact as the flight ban has been extended through the last few days. As with an earthquake or tsunami, a geological process is suddenly thrown into the public consciousness, even though it originates from far away. In this case the process is relatively prolonged and there is no-one who has any idea of how long the eruption might last or how the winds might be moving the ash cloud a week from now. As well as having stressful consequences, there have also been benefits resulting from the ash cloud. I am staying in the south east of England, not far from Gatwick and Heathrow airports. For many people this is the first time ever that they are able to sit in their back yards and have a conversation without being drowned out by the roar of aircraft overhead. The weather has been sunny with clear skies, with no visible sign of the ash cloud that is causing so much disruption. News bulletins are filled with the scientific background, economic predictions, traveler’s personal stories and political commentaries. I have been increasingly grateful for my good fortune in having got here just in time, whilst wondering if my return journey at the end of April will be equally unaffected. There are direct lessons to be learnt for NZ too as Gill Jolly and Graham Leonard, both volcanologists at GNS Science, describe in this media release

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Tararua Range

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With Uwe Morgenstern, also from GNS Science I hiked the length of the Tararuas just north of Wellington over 4 days. The Tararua mountains are a section of the ‘backbone’ of New Zealand. They are made of greywacke rock, pushed up by the tectonic forces of plate collision. Like most of New Zealand’s mountains, they form an obstruction at right angles to the prevailing westerly winds and are renowned for high winds and high rainfall – often making for tough tramping. Luckily for our trip we had very stable and clear conditions, a rare treat! We set out from the Putara road end near to Ekatahuna, at about 9am. After following a stream and hiking upwards in the forest, we came out into the open tussock after a couple of hours. It was quite cloudy through the day. This made for an amazing sunset as we continued along the ridge to Arete Hut which we reached after dark. For the final hour and a half we had to navigate by map and compass, with a bit of searching to finally reach our refuge for the night. Day 2 saw us following the ridge for hour after hour. the distant point on the horizon was our objective for the night and again we reached Jumbo Hut after dark. We passed by this possum that seemed to have lost its way and was hiding under a rock well above the tree line. Day 3 was our longest day. Leaving Jumbo hut at about 7am, we traversed to Mount Holdworth, then dropped down through the forest to the Mid Waohine Hut which we reached at about 11am. After a very brief dip in the river, a long and exhausting climb saw us back on the tops further to the West. From Aokaporangi Peak we headed to Maungahuka Hut which we reached about 5pm. After a short break we decided to keep going in order to be able to complete our traverse in time for work on Monday. As fast as possible we dashed over the Tararua Peaks – very steep ground which we didn’t fancy attempting in the dark. Soon we were beyond them and darkness was upon us. Four hours of arduous tramping by headtorch we arrived at Kime Hut and the end of a fifteen hour day. All that was left was to complete the Southern Crossing of the Tararuas, over Mount Hector and down the less travelled Quoine Ridge. The views in all directions were spectacular, including Taranaki and Ruapehu volcanoes, our own route through the Tararuas, the Wairarapa Plains, Palliser Bay, the Rimutaka Ranges, Wellington Harbour and the Kaikoura Ranges of the South Island. Just above the tree line we came to this GNS Science continuous GPS station cemented into the bedrock. This device is part of a nationwide network that continuously monitors the horizontal and vertical displacement of New Zealand on its plate boundary. As we descended, we entered the Goblin Forest – a wierd world of beech trees covered with mosses and lichens. Finally by 5pm we arrived at our awaiting vehicle and the prospect of a very satisfying rest.

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Marlborough and Kaikoura from the air

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Yesterday I was offered a flight from Paraparaumu Airport to Kaikoura by Felix Morgenstern. His father Uwe is the water and ice dating specialist here at GNS Science. This was a great chance to admire some fantastic landforms created by the uplift of the leading edge of the Australian Tcctonic Plate right up close to the collision boundary, just east of the north end of the South Island. We flew directly south across Cook Strait, away from Wellington’s cloudy skies to a clear day over the South Island. This picture shows the coast of the Wellington Peninsula fringed by marine terraces that have been uplifted and tilted by successive earthquakes. Cook Strait is in the foreground and the white wind generator towers are making use of windy Wellington’s prime natural resource! On the other side of the Strait, the skies were clear. This is a view across the coastline to the south-east of Blenheim. The rocks that underly this landscape include several locations where the famous K-T boundary layer (Cretaceous – Tertiary or Cretaceous Paleocene boundary) is exposed. This thin dark layer of clay is found at different places worldwide. It marks the point in time when a massive asteroid impact in Mexico caused the extinction of the dinosaurs and many other life forms. One such place is the rocky hillside near to the true left of the river in the foreground. Soon we were passing alongside the inland Kaikoura Range, whose highest peak is Tapuae o Uenuku at 2,885 metres. It is made up of a complex of resistant igneous rocks, thought to be of Cretaceous age. Faults active for the last 20 million years are lined up along each side of the range, parallel to the plate boundary just off the coast. These are mainly strike slip (sideways moving) faults but there is also significant vertical movement pushing the mountains up by up to 10 mm a year. I took this picture as we were approaching the Kaikoura Peninsula. Suspended sediment in the sea from river outwash has developed into a nice spiral shaped eddy. Beyond the narrow peninsula is the area where the Hikurangi Trough meets the coast of the South Island. The Kaikoura Canyon – a deep slice in the ocean floor just off the coast, has created a haven for wildlife there including whales and other marine mammals. After landing for a short while at the Kaikoura airstrip we took a short detour out to sea. We didn’t see any whales but there was a crowd of dolphins surrounding a boat. A nice way to leave Kaikoura behind.

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Palliser Bay

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Palliser Bay is an isolated sweep of coastline about 2 hours drive from Wellington. It is separated from New Zealand’s busy capital city by the Rimutaka Range. Yesterday I visited the area with a group of Lower Hutt school children as part of their Year Seven geology camp. Fully armed with the “Kiwi Fossils Hunter’s Guide” as well as another excellent book by Lloyd Homer and Phil Moore that describes the geological features of the Wairarapa Coast called “Reading the Rocks“, we visited several great geology hotspots along the coastline. A striking feature that we noticed straight away was the flat topped escarpment that runs along much of the coast. This is a raised marine terrace that was at sea level about 80 000 years ago. It indicates that the whole area has been undergoing an enormous amount of uplift which continues to this day. First stop was Hurupi Stream. (This is described in detail in the “Kiwi Fossils Hunter’s Guide“). The soft mudstones at the sides of the stream were deposited under the sea in the Miocene Epoch (sometime between 11 and 7 million years ago) , when the Aorangi Range just to the North was an island, separated from other parts of the North Island by a shallow sea. We found quite a few marine molluscs that are very well preserved and easily spotted. Not far along the coast road are the Putangirua Pinnacles. These spectacular features have been eroded out of a thick sequence of conglomerate. Hard layers or large individual boulders within the conglomerate form a protective cap at the tip of each pinnacle. The ground is strewn with loose rubble – testament to the fact that the erosion here is still very active. This might not be the best place to visit in a rainstorm! A few kilometers along the coast road, there is a dramatic example of coastal erosion where a whole section of the original road itself has disappeared! We followed the coast past the small settlement of Ngawi, and a huge tilted slab of fossiliferous sandsone called Kupe’s Sail, to the Cape Palliser lighthouse. This is built on a cliff of volcanic rock that was erupted under the sea as pillow lavas about 100 million years ago. The long staircase up to the lighthouse leads up to a great viewpoint. This is the Southeastern tip of the North Island of New Zealand, with nothing but ocean between here and Antarctica or South America. Just a few kilometres out to sea is the Hikurangi Trench, the collision boundary between the Pacific and Australian tectonic plates. The connection between uplifted terraces, fossils, erosion, earthquakes and volcanoes gave us all something to think about to round off our geological excursion.

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Turning over an old leaf with the Fossil Hunter’s Handbook

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If you are reading this blog, you presumably like the idea of getting outside and appreciating the landscape and its underlying geological features. James Crampton and Marianna Terezow are paleontologists here at GNS Science. They have just published a great book for fossil enthusiasts called the Kiwi Fossil Hunter’s Handbook. It is full of interesting information and highlights a number of prime localities around the country for unearthing nice fossil specimens. After a conversation with James,, and armed with information from one of the chapters in the book, I recently visited a fossil locality near Murchison in the South Island. About 6.5 kms north of Longford on the main State Highway 6, there is a sign indicating Nuggety Creek Road. A few hundred metres along the track there are some crumbling cliffs by the roadside. This is a fantastic place to collect fossil leaves from the Miocene (about 16 – 13 million years old). They were deposited in a river valley that was surrounded by a rainforest. Boulders at the foot of the cliff are absolutely packed with leaves of different plants. There were large trees here as well as smaller plants such as ferns living beneath them. The rock is quite crumbly, so it can take a while to find a lump that is solid enough to stay in one piece. These fossils are evidence that the climate in New Zealand in Miocene times was very humid and warmer than at present. As you can see from the last photo, some of the fossil leaves are superficially very similar in appearence to modern leaves found at the same locality today.

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Cretaceous Reptiles in Hawke’s Bay

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Over the last few days I have been with a GNS Science team exploring the remote Mangahouanga Stream in inland Hawkes Bay. This is the area that is famous for the discoveries of dinosaur and other reptile remains by Joan Wiffen (who died in June last year) and her team. It is on private land, deep in the forest and therefore rarely visited. Bones of marine reptiles seem to be relatively common in the hard concretions in the stream bed, but land dwelling dinosaur remains are very rare as they were washed some distance into the sea and separated before being buried in the sediments . An example of a therapod dinosaur toe bone, discovered by Joan Wiffen can be seen as a 3D image here On the way to explore the river we passed the two expedition huts used by Joan’s team . In the picture are Mike Wylde and Tunis Keenan, two Royal Society Primary Teacher Fellows being hosted by GNS Science this year.   After following a rough track through the bush, we reached the Mangahouanga Stream. In several of the large boulders we could see bone remnants. In this picture there is a large vertebra (backbone segment) of an unknown species of reptile. If you look carefully at the top of the rock in the right foreground you might see an oval shaped brown lump which is another similar vertebra. Here John Simes (GNS Science palaeontology collections manager) and Pete Shaw (forestry manager) check out a rock slab containing shells, sharks teeth and fish bones. Have a look at our video of fossil hunting in Mangahouanga Stream:

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