Fossil Favourites from GNS Scientists

GNS Science recently produced a new "Photographic Guide to Fossils of New Zealand". It is a small, pocket sized booklet, packed with photos and information about many of our characteristic fossils. It also contains a very readable introduction to New Zealand geology, the fossilisation process and the geological history of New Zealand.

You can find more information about the book, including how to get hold of a copy; here. It is published by New Holland Publishers.

Here is the team that created the guide, from left to right: James Crampton, Marianna Terezow, Alan Beu, Liz Kennedy and Hamish Campbell.

I asked each of them to choose their favourite image from the book and say a few words about it.


Here are their comments:

James Crampton:

Cretaceous ammonite, scalebar is 1cm

My favourite fossil is the small Cretaceous ammonite on the bottom of page 62.  Ammonites are very rare in New Zealand Cretaceous rocks, although they are extremely common in other parts of the world.  This one came from the coastline of Raukumara Peninsula, north of Gisborne, from a lovely, wind-swept, wild, and pohutakawa-lined rocky shore.  This specimen is well preserved and shows how some species deviated from the typical, simple, flat spiral shell form of most ammonites - in this case, as the animal grew, the shell became partially uncoiled to end up looking like a hook.  In life, the animal had many tentacles and extended out of an opening in the shell at the point where the label is fixed (this opening is now filled with rock).  This ammonite was found with many fossils of strange clams that were specialised to live on deep-sea seeps - places where methane was naturally bubbling out of the sea-floor during the Cretaceous Period.  These clams probably ate bacteria that, in turn, survived by using chemical reactions to 'feed' on the methane.

Fossil shells from Hakateramea, New Zealand

Marianna Terezow

My favourite photo is the one that resides on the title page. It’s an image of a late Oligocene-Miocene limestone block from Hakateramea, South Canterbury. I love this photograph because it showcases some of the great variety of marine life-forms found throughout New Zealand’s fossil record. From small filter-feeders like the clam Limopsis to the large, carnivorous snails such as Magnatica, this image is a snap-shot of a once-living, thriving marine community. I find these life stories of community dynamics that fossils tell us very fascinating.

Struthiolaria frazeri - scalebar is 1cm

Alan Beu

My favourite image is Struthiolaria frazeri, on page 122. This is the largest, most spectacular and most elaborately sculptured of the "ostrich foot shells", family Struthiolariidae, which are almost entirely limited to New Zealand, and are one of the really characteristic elements of our fauna. They display a long, complicated history of evolution and extinction, with more than 35 species occurring as fossils over more than 40 million years, and yet only two species still live here now - Struthiolaria papulosa (top of p. 123) and Pelicaria vermis (p. 123, lower on the page). Struthiolaria frazeri provides a clear example of extinction, as it is a key fossil for identifying the end of the Nukumaruan Stage, becoming extinct suddenly 1.6 million years ago, at a cooling spell.  Presumably it was a warm-water species, as it is mainly found in shallow-water rocks in central and northern Hawke's Bay, with a few specimens found near Whanganui. The very obvious sculpture of prominent, square-section spiral ribs, the tall spire, and the short, oval aperture with thick, smooth lips and a deep sinus in the top of the outer lip make it easy to identify.

Cretaceous broadleaf - scalebar is 5cm

Liz Kennedy

My favourite image is of an undescribed Cretaceous broadleaf angiosperm leaf base and podocarp foliage on page 54. These beautiful leaf impressions, along with many other leaf specimens, came from very hard grey sandstone overlying a thick coal seam which was mined at the Strongman Mine opencast near Greymouth. They are a glimpse of the vegetation which made up New Zealand’s Late Cretaceous forests which were very different to those of today, a time when dinosaurs still wandered about, perhaps even eating this kind of angiosperm leaf. These leaf impressions are generally well-preserved, with the ridges of prominent veins providing texture to the impressions. An assemblage of leaves such as these can provide us with a fascinating picture of the past including what kinds of plants covered the Late Cretaceous New Zealand landscape, how diverse the vegetation was and what the climate was like when the plants were growing.

Historic fossil locality in the Chatham Islands

Hamish Campbell:

"My favourite image is on p.25. It captures not only fossils but also a 'fossil moment'. After all, photographs are fossils of a kind...preserving a record of things that happened long ago. This beach on the north coast of Chatham Island is famous because this locality, with fossil oysters that are 50 to 55 million years old, is the very first fossil locality to be formally recorded in the scientific literature from New Zealand. It was collected by Ernst Dieffenbach in 1839 and he sent the fossils to the Natural History Museum in London. Oddly enough, this locality was 'lost' for more than a century because it was buried beneath a sand dune. It was only rediscovered by us paleontologists at the time of this photograph in 1995."

Fossil Whale Hunting

Last weekend I returned  to our fossil whale locality in Palliser Bay with John Simes, the paleontology collections manager at GNS Science. This is where I had found three large jaw bone fragments of a fossil baleen whale last November.



We decided to have a good look through some of the loose debris in the area where I had already made some finds.
After some time. John spotted another large piece of mandible, very similar to the ones that we had from the previous visit.

I decided to try the direct route up the cliff, to get closer to the source of the bones. The ice axe proved to be quite useful for making progress up   the very crumbly mudstone. This got me about half way up the gully, to a point that I had reached last time and where I had found one of the three original bones. On this first re-inspection I didn't come up with any more fossils.

The next plan was to abseil down into the gully from the top, in order to have a very close look at the steep headwall which seems to be the actual source of the fossil whale. I had to take care not to dislodge any large rocks with the rope. Unfortunately this inspection of the cliff didn't reveal anything even with careful scrutiny.

Back in the bed of the gully, I dug around with my ice axe some more and did at last come up with three smaller pieces of bone. Here you can see one of them - we think it is the end of a jaw bone, although it is much thinner than the other pieces.

Back in the macropaleontology lab at GNS Science, the thin layer of mudstone coating the bones was quite easily cleaned away with the help of a pneumatic air scribe. The 30 cm long piece shown here turns out to fit perfectly with the previously found  segments of the mandible, giving us a combined total length of 1.5 metres for it.

The missing link puts it all together. The latest piece in the puzzle is second from right. The rest were found on the previous trip.

Here are the smaller pieces after a bit of cleaning. It is tantalising to think that there must be a lot more of them waiting to be discovered in the mudstone of Palliser Bay.

Titahi Bay Geology

Titahi Bay is a great place to visit if you are interested to see some of the geology near Wellington. There are a number of very interesting features to look at and explore. The first thing to check out is the coastal landforms caused by a combination of the atmosphere and  the sea, as well as the variable resistance of the rock, and a history of earthquakes (uplift). The first image is taken from the Pa site, a few hundred metres north of Titahi Bay beach.

If you are a teacher, this is an excellent place to encourage your students to observe some of these natural features, such as sea caves, sea stacks, arches, marine terraces and wave-cut platforms. There is more information about how these features form on the GNS Science website .

This sea cave marks the line of weakness of a fault. It is no longer at sea level, having been uplifted out of range of the water by earthquakes. It is also a useful way through the rocks between two small embayments.

A striking feature of some of the rocks at Titahi Bay is this type of weathering out of the spaces between joints to form distinctive criss cross box structures



Having looked at the erosion and weathering features along the coast, the next thing to do is have a look at the structures and the rocks themselves.


In this photo you can see that the rocks are made up of alternating bands of massive sandstone, with in-between layers of dark mudstone. These rocks were formed from sands and muds eroded from the margin of Gondwanaland, long before New Zealand existed. The material flowed down into the deep sea and settled over wide areas. The coarser sediment, at the base of each of these submarine landslides, is represented by the sandstone, whilst the mudstone gradually settled on top.

After deposition, the sediments were squeezed and deformed by the bulldozing effect of plate collision along the edge of Gondwanaland. You can see how the originally horizontal layers are now  almost vertical at Titahi Bay. Many faults are easy to spot, as they displace the clearly defined rock layers.

As well as faults there are also folds in the rocks such as the anticline (upfold) shown here.

An interesting challenge is to look for sedimentary features such as graded bedding or cross bedding, in order to tell the direction of younging of the steeply tilted rocks.  In this photo you can see some cross bedding, showing where the rock above my finger cuts across some fine layers that must have been layed down first.

If you have time whilst at Titahi Bay, and if the tide is out, you should have a look at the tree stumps of the fossil forest at the south end of the beach. It seems almost unbelievable that these wooden stumps date from a time before the last ice age, about 100 000 years ago. The fossil forest does actually extend right along the beach, but is mostly covered with sand. On rare occasions, about once a decade, storms clear the sand away to expose much more of the forest than you can see here.

Look carefully and you can see the growth lines of these ancient tree stumps.

Volcano Gas Flights Video

If you had to work out the daily quantities of different gases coming out of a volcano and spreading across the sky in a huge, mostly invisible plume, where would you begin?

This video gives a brief introduction to how New Zealand's GeoNet scientists go about it:

The information is combined with other evidence such as seismic monitoring to judge the risk of future volcanic eruptions.

Flight over Tongariro and Ruapehu

My next experience of a GeoNet gas monitoring flight was over Tongariro and Ruapehu. This time Karen Britten and I were joined by Fiona Atkinson (left in photo) who is part of the GeoNet volcano monitoring team.

As we approached the volcanoes from over Lake Taupo, the small gas plume from Te Maari was visible. Because the plume is quite low against the mountain side, GeoNet cannot always monitor it by plane. They sometimes use a road vehicle instead, traversing under the plume along a nearby road.


Our flight took us past the Red Crater (left) and the Emerald Lakes, where I had been tramping a few days before. North Crater on the right skyline is a solidified lava lake, whilst the dark lava flow in the middle distance on the right originated out of Red Crater.

We circled Ngauruhoe several times just in case there was some evidence of gas emission, although non could be determined. If you click on the photo to enlarge it you can just see some people on the left hand side of the inner crater rim.

The crater lake of Ruapehu was a uniform pale blue colour, with no visible upwellings. Our gas measurements showed about 670 tonnes per day of CO2 , a little H2S (0.5 t/day) and about 28 tonnes per day of SO2. These figures are in a similar range to those from the end of January, but somewhat elevated compared to December.

On the way back we decided to take a closer look at the Upper Te Maari crater area. There is still a lot of grey ash covering the area from the November 21st eruption, and yellow sulphur deposits around the fumeroles.

Having landed back in Taupo, I drove down to Whakapapa Village, and was able to look at the Te Maari area from the road on the way. The area affected by ash can be seen extending across the mountain side.



I decided that I just had time at the end of the day to walk up Te Heuheu peak on Ruapehu. It is on  the north edge of the summit plateau.  The crater lake is just beyond the sunlit snow in the centre of the photo, out of sight behind the ridge



In case you haven't seen in yet, here is a video of the Te Maari eruption made from the webcam shots on November 21st: