Greywacke Bedrock - the backbone of New Zealand
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- เผยแพร่เมื่อ 19 มิ.ย. 2024
- Where did Aotearoa New Zealand's most common greywacke basement rock come from? A dive into the deep geological history of New Zealand will explain.
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This video was supported by GNS Science's Understanding Te Riu-a-Māui / Zealandia research programme, which investigates the geology, past climate, natural resources and hazards of Aotearoa New Zealand and the surrounding ocean floor.
Love your channel and the clear way you explain things. You live on a very interesting part of the planet, lots going on.
Thanks! Yes, it's an active land for sure
Where the hell was this channel when I was studying geology 20 years ago!
I don't think there was TH-cam then!
@@OutThereLearning well that just makes me feel old. Might need to get the Zimmer frame out to get around the outcrops soon
Brilliant, absolutely loved this overview of NZ's formation boxed into 8min, makes you realise our existence is just a speck in time.
Thanks Ron!
How fortunate we are to know more about the physical history of the unique and beautiful land we love . Thank you
My thoughts too :-)
Thank you so much. It's always great to see Zealandia's great journey!
Thanks for your comment, glad you enjoyed it.
Awesome, Well done and thank you
Cheers!!
I never knew the South Island used to be up against the North Island like that and migrated down. So fascinating 😀👍‼️Great job explaining.
Yes- Thanks for your appreciation!
Very interesting. Thank you.
Thanks!
It fascinates me that parts of Gondwana land is still visible on the coast lines of New-Zealand.
Thank you. This was a very clear explanation, and very interesting
Thanks!
Captivating explanation. Fundamental knowledge for all New Zealanders. I always wondered what Greywacke was, so it can be both Sandstone and Siltstone.
Thanks for your comment 👍
A very good explanation of an exceedingly complex geological region.
Thank you!
Just found this interesting and enlightening video describing the geology of NZ and subscribed immediately. I have watched all of Nick Zentner's geology lectures on Washington state with interest and as a world traveller it pleases me to understand the amazing complexity of geologic issues of our amazing world and its natural forces. I will continue to watch and learn more. Greetings from the Train Lord in South Australia.
Thanks for your comment. Glad you liked it
Excellent explanation! 💖
Thanks!
That was great. Thanks so much.
You're very welcome!
thank you.that was awesome
Cheers! Glad you think so
That is absolutely fascinating.
Glad you think so!
Great information , well explained. It gives me a better understanding of all plate tectonics. Thank you.
Thanks - glad it was helpful
Excellent. Concise, informative and no waffling.
Thank you.
Thanks for your positive feedback!
Very nice. Thanks
Most welcome
Great presentations. Very informative and easily understandable. Thank you.
Thank you for your kind comment
I live on the same type of rock here in Nova Scotia. Some of the coastal scenes are very familiar looking.
Nice one.
Cape Bretoner here currently in New Zealand 👋🏻 I find the coastlines here so similar to home and its probably why I don't feel so far away 🌿🌄🇨🇦🇳🇿
The presenter is very personable.
Great stuff..thank you.
🙂 thanks
Thank you, very interesting!
You are welcome!
Thank you very much for these fascinating accounts. You are bringing my university degree, which included geology, up to date. What a wonderful world we live on !
Thank you for your comment David
Pleasure meeting you in Oamaru today ( and please excuse the intrusion). Would so have loved to pick your brains a bit but I guess I'll do that if (when) you come back down here on an official visit for the Geopark seminars.
Nice to meet you Andy, thanks for saying hi, not an intrusion at all!
Great summary! Thanks from Sweden
Glad you enjoyed it!
I learned about greywacke as a kid. If you make a fire outdoors, and you surround it with a ring of (river) rocks, some of the rocks will crack and explode, from the heat. The adults said, ‘Oh, that’s greywacke. Don’t choose those ones for the fire, they pop.’ The idea was they contain water deep inside, but that was speculation, I don’t know if they do.
Yes good reply I heard that too from watching guys n gals Off The Grid wild camping in the bush.
I think it is more likely that they have planes of weakness so that when the outer part of the rock heats and expands, they easily crack apart
Rock strata shows Kahurangi national park moved up from Southern Mount aspiring National park.
Indeed - the total displacement along the Alpine Fault is about 480 km!
Great knowledge
Thanks!
Beautiful summary. Thank you
Thanks!
Fascinating 🖖🏼
Agreed!
He best explanation I have seen.
Thank you, much appreciated :-)
Good outline. Well done.
Thanks!
Clear and enjoyable story of NZ. Real good us of my lesson preparation time.
Thanks!
Fantastic. Thank you for this content!
Thanks for your appreciation!
Fascinating stuff.
Glad you think so!
Extremely interesting, thank you.
Glad you think so!
It would be interesting to include the weathering and erosion and uplift processes resulting from changes in sea-level during and between ice ages. During ice ages when sea level dropped 140m for about 100,000 years there must have been terrestrial plant and animal species living on what is now sea floor.. including swampland and forests and aquatic lakes.
Great idea
Thank you..I have shared on our FB page Kiwiquakes to show our members
great!
Excellent context for all your other clearly explained vids.
Many thanks :) 👩🦳👵👩🏼🎓🧘🏼♀️
Thank you!
Many thanks. I spent some months working with the late Dr Chris Ward doing field work in Dusky Sound in the early 70's, and along the way I picked up an enduring, if rudimentary interest in geology. Part of me finds these videos you're making here almost unreasonably satisfying and not a little nostalgic
Thanks for your comments - great that you like the videos :-)
I've always been fascinated by how the subduction zone seems to twist under Southland. Plate subducting under east side of North Island, yet pops out the SW corner of South Island subducting in the other direction. The Zealandia continental plate history helps explain this, but it's still really weird and amazing to me :)
Lachlan and I really enjoyed this video!
That's great - thank you
That s why you find jade in South Island bravo very good look on the geological point of view
Cheers!
Awesome
Thanks!
I am forever grateful, educated, amazed at what I have learnt here by exceptional 'Kiwi' & the many hours putting all this powerful information together that formed our land & this Southern part of a awesome Planet we call Home. Kia Ora (aha so Northern Kiwi you could be called Mozzies) sorry tongue in cheek - all the same love these video's.
Thank you for such a kind comment
Thanks
Cheers
And the city of Porirua!!
Mind-blowing stuff. Reminds me of the clock face metaphor showing the timescale of the formation of our planet, with emergence of early hominids at just a few milliseconds before the top of the circle (maybe even micro-seconds). And here we are, close to eliminating ourselves from the picture 😢. Maybe you could include that clock face in one of your videos?
Thanks for your comment and your suggestion!
Very useful for my uni assignment! Thank you. This is way interesting than the geo here in Sydney....:)
Glad it was helpful!
This is what I called it for years ROTTEN ROCK
🙂 especially if you were a climber!
@@OutThereLearning I was a hunter in the Coromandel lots of it up there
hi great vids . have you done any work on the catlins mountain range , that goes 90 degrees to the southern alps , that is also incredibly straight as well .
another strange place , i am curious about is albatross point at kawhia , which a classic up lift on one side and on the other side it goes down in to the sea , with a very straight edge .
Hi there, thanks for your comment and questions. I haven't much knowledge of the Catlins, but I think the overall structural alignment E to W is a remnant of the deformation (folding) along the Gondwana margin due to plate collision at that time. Further west this alignment has been smeared northwards by movement along the Alpine Fault. Cheers, Julian
Excellent extra info in answer there Julian. Many thanks. I do find that whole Southland geology fascinating. Although too cold for me to spend much time down there!!
My understanding of this event is that the eroded "debris" was deposited into a huge basin? Was there a "basin? Thanks for the informative explanation
A! this is valuable and as a Kiwi Very Very interesting - like shit loads interesting ... this is why New Zealand is Slipping/Washing away in Northland.
Very interesting and brilliant channel. Even in the past, Zealandia was a submerged continent?
Thanks for your comment
Julian - I've just noticed that once this vid getts into the screen-shots/maps-sequence, the visuals I'm seeing are well ahead of the spoken word.
Example: At 1:59 the cursor is circling/indicating the deep-ocean layer (coloured blue) to the west of Fiordland, yet the voiceover makes no reference to this until 2:18.
Similarly - at 2:25 the cursor start pointing to the undersea drill-sites, yet the voiceover does not get to this detail until 2:43. (the same lag-time; approx 19sec.)
It makes it very difficult to follow.
I've made video-sequences myself, and it's dashedly difficult getting things to exactly match up, so you have my sympathies. And I also know that youtube vids cannot easily be edited once uploaded - except to clip their toes or tails off. Good luck!
It comes right at about 5:50.
And it is still, overall, a thoroughly detailed walk-through. Thx!
Hi Ged,
Actually the cursor lines up fine with the narration when I look at it. Could your playback have been slowed down in some way perhaps? Either way it isn't possible to change at this point ! Thanks for your interest and your comments
@@OutThereLearning Extraordinary!
Okay, then, if it looks good at your end, then I'll rest my case. I've seen crazier things on the internet!!
Great video!
One thing I have wondered about for ages - greywacke seems to be very poor when it comes to fossils - especially fossils of large animals and plants. Why is that? What is it about greywacke that makes it not contain these fossils?
Given that much of NZ has been underwater for ages, I would expect to see (for example) **lots** of plesiosaur and mosasaur fossils but there are very few!
Fair point. The sediments were laid down quite far away from land in relatively sparsely inhabited water, and were also very mildly metamorphosed by burial which might have had some impact. As you say there have been a few isolated vertebrate fossils found, but mainly just worm borrows and other trace fossils of bottom dwellers.
Surely larger animals weren't around when this sediment was being built up?
Amateur geologist Joan Wiffen in the 70s managed to find alot of fossils in very remote areas of Hawke's Bay. There's probably still more to be discovered if you're prepared to do some serious tramping expeditions.
Awesome stuff. It makes me feel a bit safer living in Auckland, I can see I'm a little bit away from the faultline. Cheers.
Yep - just watch for magma coming up from below!
@@OutThereLearning Heh! Yeah I saw that in a video you did about the Hikurangi subduction. Water in the inter-plate slurry. Cheers.
Thankyou
You’re welcome 😊
Have you been up to Boulder hill in the Belmont regional park? Love to know your thoughts on the boulders up there.
Great question. They are basically super hard concretions that have eroded out of the greywacke and been left stranded as the softer material eroded away. You can find them all over the hill tops and gathered in the valley bottoms too.
Thanks for watching
@@OutThereLearning thanks for the reply and I thoroughly enjoy your videos!
Wow!
That's the sort of response I like :-)
Is there any interest in the Mangatainoka area the landscape there is quite different. Did some fencing up in the top hills, seeing this made me wonder if it’s similar.
I'm not familiar with the area there, but you are likely to be in much younger (2 to 4 million years old) gravels, silts and limestones from a time just before that part of the Wairarapa was uplifted above sea level. But don't quote me!
You're crushing it
Cheers!
I think the Australia/Gwondona map is too new. Thought that Stavely arc in western Victoria is 500+Ma and Macquarie arc in NSW is about 450Ma
Awesome video! Which institutions do you recommend, to study geo science in NZ?
Don't have the knowledge to compare them, sorry, but I am confident that all the main uni earth science courses will be good
Not sure I subscribe yet to the New Continent theory due to a lack of basement igneous rock / Gneiss, unless there are deep cores I see it as erosional material from Gondwana sitting on a Basaltic base which has undergone subsequent rifting.Thus an accretionary prism. Ancient igneous provinces such as those in Canada, South Africa have their roots extending deep into the upper Mantle. is there evidence of older basement rock - beyond the middle Cambrian ? Enjoyed the video - a link to the description of the source of the Torlesse supergroup and the timing - Permo triassic ( the Mass dying) a worthwhile mention.
Thanks for your thoughtful comment. We know it is continental crust from extensive gravity and seismic surveys (seismic velocities) that tell us that the crust is very thick and that there is no oceanic crust underneath Zealandia.
Good question. You are correct that the greywacke sediments were originally deposited along the eastern margin of the ancient continent of Gondwana in a trench where the adjacent oceanic crust was subducting down to the west. That convergent motion caused the sediments to be scraped off and "accreted" to the easternmost edge of the old continent. Inside this so-called accretionary prism (wedge), the sediments were faulted and folded over each other and the ones forced deepest - those closest to the old continent - were metamorphosed into schist and gneiss. Granitic magmas of what would eventually become the Median Batholith intruded along the boundary between the old continent and younger accreted sediments and metamorphosed rock to "stitch" the two together. When this composite ribbon of older and younger rock split from Gondwana, Zealandia was born. The new continent is quite literally a chip off the old block, but only in part because it also includes the newly added rocks of the Median Batholith.
Do you have an explanation for why zealandia separated from Gondwana? Is the Tasman sea still increasing in width?
Thanks for your interest and question. The Tasman sea was opening from about 85 to 55 million years ago but has stopped expanding since then. Why subduction stopped and Zealandia rifted away from Gondwana is a great question and a bit too much to go into here, especially as I don't know the full answer! Basically plate boundaries evolve and shift through time. If you think globally, when one subduction zone initiates another will stop somewhere else and vice versa.
I might have missed the bit where you explain what greywacke is ? Is it just sedimentary rock ? does it occur elsewhere in the world and if not why? Cheers
Thanks for your question. Greywacke is a type of sandstone with mixed sized particles, typically created by marine avalanches that form deep sea turbidite deposits. Also found in other parts of the world such as the UK and South Africa.
@@OutThereLearning Thanks! :)
Oh Great New Zealand
is built of Sand Stone ... yeah I deliberately hit Enter
Sand stone ... ok there is some Bedrock but most is sandstone - like yesterday - as opposed to a week ago
Show us graphics of future movement please 🙏
NZ is a good place👍🇳🇿
Yep - for sure!
Is it greywacke or Metagreywacke?
200 million years x 50mm\yr = 10,000 km. Seems about right.
sup 10b
sup classbuddy
@@alexcraig6756 ok
Rule Zealandia, Zealandia rues the whales!
:-)
Do you think there is gold in those hills.
There is gold in some parts of New Zealand, and there was a gold rush in Otago in the 1860s. So there you go!
@@OutThereLearning thank you for your reply. Your uploads are really interesting
Gold was mined on Terawhiti Station just west of Wellington city . There are mining tunnels still there to this day if you know where to look .
Greywacky?? That's not Nice.
True
lit
thats pretty gay