Greywacke Bedrock - the backbone of New Zealand 

Thanks! Yes, it's an active land for sure

Thanks Ron!

I don't think there was RU-vid then!

@@OutThereLearning well that just makes me feel old. Might need to get the Zimmer frame out to get around the outcrops soon

My thoughts too :-)

Thanks for your comment, glad you enjoyed it.

Thanks for your comment 👍

Thanks for your comment. Glad you liked it

Thank you for your kind comment

Thank you!

Thanks for your positive feedback!

Thanks - glad it was helpful

Yes- Thanks for your appreciation!

Thanks!

🙂 thanks

Thank you for your comment David

@@christinedaly2694 cheers!

Glad you enjoyed it!

Cheers!!

Glad you think so!

Thanks!

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

Thanks!

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 🌿🌄🇨🇦🇳🇿

Nice to meet you Andy, thanks for saying hi, not an intrusion at all!

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 :)

Thanks!

Cheers! Glad you think so

Thank you for such a kind comment

great!

Thanks!

Thank you, much appreciated :-)

Thanks!

You are welcome!

Most welcome

Thanks for your appreciation!

Thank you!

Glad you think so!

Indeed - the total displacement along the Alpine Fault is about 480 km!

Thanks!

That's great - thank you

Thanks for your comment and your suggestion!

Great idea

Agreed!

Glad you think so!

Thanks for your comment

Cheers!

You're very welcome!

Cheers

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!

Thanks!

Glad it was helpful!

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.

🙂 especially if you were a climber!

@@OutThereLearning I was a hunter in the Coromandel lots of it up there

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!!

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.

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!!

Don't have the knowledge to compare them, sorry, but I am confident that all the main uni earth science courses will be good

Cheers!

That's the sort of response I like :-)

You’re welcome 😊

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.

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!

Yep - for sure!

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.

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! :)

:-)

thats pretty gay

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 .

sup classbuddy

@@alexcraig6756 ok

True