Im not gonna look at them the same way next time im walking in stanmore bay. I pity anyone else walking with me.. I think i will start with "Did you know...." Thanks so much for your awesome video!
I'm so glad you posted this. I've been intrigued by the cut away hills on the new section of motorway between Orewa and Warkworth and this video explains these formations. Cheers.
Very interesting explanation thanks. Your comment regarding the rate of mud deposition, "...as say 10mm per thousand years" (abt 3:05) sounded like a bit of a guess. To me, the uniform boundaries between all those layers implies that they were all laid down in rapid succession. If there had been thousands of years between I would expect to see much more disturbed boundaries between the layers - caused by the erosion and animal and plant activity that thousands of years would normally allow.
A Brit. here, interested in Earth Sciences. New Zealand is fascinating for geology as the many features are often so accessible, easier than in the UK. I spotted some very clear, not too difficult to interpret features, when I spent two months travelling around both your lovely islands. Many thanks for the clear demonstration and explanation.
@@watsonrangi6236 I'm unsure of the intentions of your question. Are you unfamiliar with the use of "national treasure" to describe a person, place or object that is held in esteem and seen as valuable to people of a nation?
A few years ago I came to NZ for the first time from northern Europe. Traveled little around on the country side. Remember when strolling in the water checking small rocks, I saw this kind of layers in one bay. Couldn't understand how they were formed. Great to finally get an explanation, thank you.
What a fantastic video, thankyou! It explained things I'd wondered about while visiting and climbing around the beaches and cliffs round Howick, Mellons Bay, Eastern Beaches
Yes , here are some strange round almost bowling ball stones I'd say iron on the western side of eastern beach that I thought may have been from volcanic eruption ?
Thank you! So many times I've looked at rock formations wondering how they formed or where they came from. I need a pocket geologist for my questions whenever I go on trips.
Wow, that was truely fascinating. I will never walk my local Auckland beach again without stopping to admire and contemplate the cliff formations. Wish you were my 3rd form teacher back in the 90's!
I live in Mairangi Bay, often walked past the cliffs. They look more stable than they really are. Since I arrived in Auckland in 1971 - ive also noticed 'Watchman Island' [a hunk of rock and some plants] close to the south side of the Harbour Bridge, getting smaller and smaller. One day it will have eroded away. LOL taking the human harbour bridge with it !! 😂
Enlightning explanation of folds, grain size orientation of up/down, etc. Anticlines, syncline explanaton brought back memories of when I took geology in Pasadena, CA, with San Andreas Fault nearby. Howhere at that time the theory of plate tectonics had not been elcidated..... it's been an exciting ride as science provided explanations. And now in 2017 a new continent Zealandia!
I'm a glider pilot and it's always great to see the countryside from above (sometimes not very above), while having it explained like this helps complete an overall picture.
Thanks for covering this. I grew up in Point Chevalier, Auckland. The whole "Point" is surrounded by coastal cliffs just like those you showed at Stanmore Bay. (Where I holidayed in my childhood in the late 50s/early 60s.) This geology is so familiar to me, but not its origin. I used to try and see if I could find and break out the largest pieces of those thinner red layers, which were shown but not specifically mentioned.
Super interesting. Dad has a place in Waiwera, and i asked him about the rocks at Waiwera Beach, but he is a boat builder and boiler maker not a geologist, so he wasn't able to go into as much detail. 25 years later and a video about similar rocks not far down the coast explains it beautifully.
This is my childhood stomping ground, so many summers spent hopping between rocks at the base of these cliffs and scrambling up amongst the pohutukawa and flax clinging to the steep sides. The fragility of this land is remarkable, seeing the way an entire hillside slips away makes me doubt the supposed antiquity of the layers. The earthquake faults stand as testament to the violent past of this green land. And what about the weirdly deep layers that are just an amalgam of everything - like a tsunami of mud has been deposited all at once.....makes you wonder.
Petrology, sedimentology, plate tectonics, weathering and erosion. I first learned about these sciences at school 55 years ago and very valuable they have been too (as a professional archaeologist), in helping to differentiate between archaeological and geological topographical features. Especially in the UK, where such phenomenon can be confusing. Having said that, I'd love to examine your very own Kaimanawa Wall for myself, one day.
Outstanding I'll head over the bridge and take a look. Love the explanation of how the larger coarse aggregates fall out of suspension first and you can re orientate good old what's up, and what was down. It always tells a story . I've read a few books, but your efforts have brought it to life, so thank you and keep the videos coming as I have subscribed . Regards Kris
Absolutely love Dr Hayward's teaching style. something about his enthusiasm really captivates my attention; without any pretension or grandeur he's revealing a legible record of history hidden in the illegible mess of rocks and dirt. a true "science communicator." Neil DeGrasse Tyson ain't got nothing on Bruce Hayward!
Thank you so much. This is brilliant. I 😂pull love to see a video about the geology of mangawhai and the volcanoes around there, the lava collums and how the white sands got there from the waitako river through the Thames way back.
Thanks Bruce, l really appreciate you and your team explaining the geology we see around us. Great work! There are interesting folds in the cliffs around Castor Bay that I had assumed were caused by the Lake Pupuke volcano, but I can see now that they would have been there before it.
Pretty sure i've heard these rocks referred to as "Waitemata chaos series" previously, due to the shear number of folds, faults and unusual beding planes :) It's also worth mentioning (while only brushed on by the video) that the darker colours and large, angular cobbles are mostly "volcaniclastic" sediments and grits from the Northland volcanic arc; the dark colour is due to ash, scoria, pumice and basalt.
Feb this year i was on the northern side of long bay reserve just south of stanmore bay. I noticed the different colored layers in the cliffs and wondered how long in the past I was looking at. Now I know 😃
Beautiful geology. I enjoyed this excursion & lesson very much. There's some similar gravel & silt features here in Hawkes Bay, will be looking at them with a different eye now! I found some white clay with pumice in it, is that from Taupo or did it float there when the land was at sea level? 🤷🏻♀️
Depending on the geological age, quite likely from Taupo or another major volcano in the Taupo Volcanic Zone. Could perhaps also have come from one of the Kermadec volcanoes that occasionally erupt pumice
One area I find fascinating, geologically wise is when driving through the Awakino Gorge, that stretch of road that weaves through those high cliffs of different coloured rock. I always pull over and wonder about how it was formed. Ive tried finding information on line but theres not allot about it. The Waitomo CAves Museum has some good info but thats about it.
Great video as always! I'd like to see a video about the Mohaka Fault - the northernmost extension of the Wellington Fault. I'd like to know when it last ruptured and what the approximate average return-time is between its ruptures. I'm also keen to know if it may have been a Mohaka Fault rupture that created Lake Waikaremoana (which was formed due to the creation of a landslide-dam - presumably created in a huge quake).
Best place for me to see these folds is low tide at Scott’s Landing Mahurangi. We were there today very few people you walk over to the island across the beach and it’s the rock between the island and beach that is the layer. You actually walk on what should be a cliff.
Fascinating, thank you very much for the education. I felt like I was back at high school or uni with an excellent teacher or lecturer. 10/10. Will try to visit that double fold at some point soon. :-)
One of my favourite drives was from Waikeretu north to Port Waikato. At Waikertu there are these layered rocks I guess formed by layers of marine deposition. Further north there are what I think are collapsed (Limestone?) sinkholes that form these large 'ampitheater' like structures. Closer to Port Waitako you can see these rounded almost spherical bubbles in the cliffs, limestone erosion perhaps? I ran off the road into a ditch and asked a local farmer to tractor me out & he asked me what I was doing there. I mentioned the rock formations and said 'oh so your a geolgist then?', No sorry just a bewildered amateur. I would love some explanation of what I saw on my drives.
Yes that part of the country has layered deep-water sandstone and mudstone deposited about 20 million years ago overlying limestones that accumulated as shell banks in shallow water about 30 million years ago, when there was very little eroding land to supply mud or sand to the sea. The shell banks were recrystallised and hardened by circulating groundwater and burial into the limestone.
What kind of events would cause such a dramatic change in geological structure? E.g earthquake? or is this just constantly happening under our feet without us noticing?
Turbidity currents can be triggered by earthquake shaking or by major storms on land bringing down vast quantities of sediment. The 2016 Kaikoura Earthquake triggered turbidity currents down 10 submarine canyons off the coast between Kaikoura and the Wairarapa.
Does the varying thickness of the sandsones give us any information about the depostional environment? Or is the thickness just a random feature of the flow path?
The turbidity currents came down submarine canyons and on reaching the floor of the basin they spread out to build up a submarine fan of sediment with distributary channels like a delta. The thickness of the sand layers deposited depended on how large the turbidity current was and whether the sand was deposited in a channel (thicker) or overbank on the submarine levee (thinner and finer). Coarser and thicker deposits were also often deposited closer to the mouth of the canyon and thinner and finer further away.
Very interesting to me. I have spent quite a bit of time observing and pondering that coastal area. Great to have some real analysis and time frames to add.. Do you have any ideas about the volcanic scoria conglomerate (or as you would more properly call them) that you see as layers in those cliffs? I think I have seen meter plus thick layers at Army bay and Wenderholme and possibly seen more widely. Its been a few years since I lived in the district but I remember wondering about where the volcanics would have come from.
How do the grains of sand in the sand stone stick together? If i filled a bucket with sand, turned it over, removed the bucket and then poured water on the sand, it would be easily eroded. Why hasn't the sandstone been eroded?
Great question. They were compacted and cemented together over millions of years due to squeezing under the compression of hundreds of metres of overlying sediment. That overlying material that put them under such massive pressure has now eroded away to reveal these rocks.
Sandstone grains are held together by a cement of some sort....the cement is deposited from mineral rich pore fluids that circulate through the compacting sediment during burial (a process known as diagenesis). Common cements are silica, calcium carbonate and iron oxides.
Hello Dr. Bruce! I'm currently in Auckland for a short course at UoA. One thing I noticed when I was in the plane was the linear features at the western coast of the North Island. Is there any reason why this is almost perfectly straight for hundreds of kilometers? I quickly checked the geology around the area and I haven't seen any NW trending faults in the area. Love your videos, by the way!
If you are referring to the actual coastline being straight, then the reason is the oversupply of sand in the coastal system on that coast over the past 2 myrs. During interglacial high stands of the sea the excess sand has been thrown up as beaches, sandspits and sand dune barriers across most of the indentations that were valleys eroded to a lower base level when sea level was lower.
@@BruceHayward1 West coast is pretty amazing. You can see geology happening in real time in the sand dunes that form the ever-shifting western edge of our nation!
@@BruceHayward1 hello Dr. Bruce. Apologies, I didn't realize I was not able to reply to your response. Thank you for answering my question. Thoroughly enjoyed my stay in New Zealand. Thank you for your videos!
hi just found you , great video . just a thought , i'm a Aussie , if you know that the same thing is here , please let us Aussies know where to look. it makes it far more understandable . and i have seen similar formations here but lol can't remember now were they are . keep up the good work , i also subscribed . THANKS
I saw what I thought was pancake eroded lave columns at Pukekiwiriki today, but after watching this I can see that they must be uplifted marine sedimentary rock. That'll be why the crater is over the hill.
A question please - wasn't there once a mighty meteor impact in the south Indian Ocean, that sent massive tsunami waves across the Tasman? Collided with Northland, rolled straight over it? Created 90 mile beach? I think there were also earthquakes and eruptions from the Kermadics that would have rolled straight into the Hauraki Gulf and surrounding cliffs? A turbulent history in these islands ...
All sorts of ideas here - some true, some myth and none to do with the features in the far far older Waitemata Sandstones featured in this video. 90 Mile Beach and the giant tombolo of Aupouri Peninsula behind was made by the slow accumulation of sand carried here by rivers and longshore drift from eruptions in the centre of the North Island. No tsunami in the world would be large enough to flow right over Northland. Yes a few submarine volcanic eruptions on the Kermadec Arc are understood to have generated up to 20 m high tsunamis that flowed up on the east coast of Northland and Great Barrier - the most recent several thousand years ago.
@@BruceHayward1 Thank you so much for your informative and interesting post Mr Hayward : ) I had to immediately look up what a 'tombolo' was in Wikipedia : 0 and also learned that it is possible for accumulations to build up over all that geological time required. Thanks for clarification that "no tsunami in the world could flow right over Northland" because I was told that this happened, by a Northlander, to explain the straight and long shape of the Aupouri Peninsula !!! Before the Internet was even thought of..... that is how myths and legends begin : )
Mud on the ocean floor accumulates at different rates depending on the distance from river mouths carrying suspended mud and submarine canyons with suspended mud turbidite tails. 10 cm per 1000 yrs is the rate measured over the last 1 million years from a deep-sea core (DSDP 594) at 1200 m depth, 200 km offshore of the major east coast rivers draining the Southern Alps in Canterbury Bight. This hemipelagic mud is a good analogue for the Waitemata Basin.
Thanks for your question. Hopefully you can tell that years of evidence based research by a lot of people has gone into building up the understanding of these rocks and the processes that created them. Cheers
This man needs to be on mainstream NZ TV
🙂👍
If he was on mainstream we wouldn’t follow him…😂
I wish my year 13 geo teacher had this level of genuine interest and fascination, instead of showing us 25 year old power point presentations
Indeed!
You had a geo teacher, lucky
thats just the schools budget mate
WE got a boring teacher who spewed out words , they didn't care about . nobody listened .
Im not gonna look at them the same way next time im walking in stanmore bay. I pity anyone else walking with me.. I think i will start with "Did you know...." Thanks so much for your awesome video!
That's great! Thanks
I'm so glad you posted this. I've been intrigued by the cut away hills on the new section of motorway between Orewa and Warkworth and this video explains these formations. Cheers.
Great - thanks for your interest and appreciation!
Very interesting explanation thanks. Your comment regarding the rate of mud deposition, "...as say 10mm per thousand years" (abt 3:05) sounded like a bit of a guess. To me, the uniform boundaries between all those layers implies that they were all laid down in rapid succession. If there had been thousands of years between I would expect to see much more disturbed boundaries between the layers - caused by the erosion and animal and plant activity that thousands of years would normally allow.
megascatterbomb
Auckland is a cluster of volcanoes,
Yesssss
A Brit. here, interested in Earth Sciences. New Zealand is fascinating for geology as the many features are often so accessible, easier than in the UK. I spotted some very clear, not too difficult to interpret features, when I spent two months travelling around both your lovely islands. Many thanks for the clear demonstration and explanation.
You are a national treasure. I love you videos because every time I watch one I learn more about the geology of our country.
Do you know the meaning of national
@@watsonrangi6236 I'm unsure of the intentions of your question. Are you unfamiliar with the use of "national treasure" to describe a person, place or object that is held in esteem and seen as valuable to people of a nation?
@@justjane805 doesn't it mean everyone in that national will know the person
Bruce was enthusiastic 35 years ago! Great to see him still in action!
A few years ago I came to NZ for the first time from northern Europe. Traveled little around on the country side. Remember when strolling in the water checking small rocks, I saw this kind of layers in one bay. Couldn't understand how they were formed. Great to finally get an explanation, thank you.
Thanks for sharing your memory and appreciation
You are an excellent teacher!
Fascinating. I am learning so much about our geology via these videos. Thanks for posting!
Great!
Thanks indeed
I love going out there Learning in these videos, thank you for posting :)
Glad you like them!
Thank you for that fascinating video. I love geology but never studied it so it's a privilege to get a free lesson 😃👍
Our pleasure!
fantastic, thank you.
Cheers!
What a fantastic video, thankyou! It explained things I'd wondered about while visiting and climbing around the beaches and cliffs round Howick, Mellons Bay, Eastern Beaches
Thank you!
Yes , here are some strange round almost bowling ball stones I'd say iron on the western side of eastern beach that I thought may have been from volcanic eruption ?
Brilliant!
Thanks!
loved having picnics here. always enjoyed following the folds of the rock with my eyes, as well as playing in the rock pools (naughty naughty!
The David Attenborough of New Zealand. I could listen all day.
Thanks for these excellent videos. Your explanations are so interesting and easy to understand
Cheers!
Thank you! So many times I've looked at rock formations wondering how they formed or where they came from. I need a pocket geologist for my questions whenever I go on trips.
Great - thanks for your appreciation!
Scott’s landing near mahurangi has some awesome diagonal or folded layers
Indeed it has, as have many places around the coast.
Well explained. I feel like I have a better understanding now. Those huge folds are impressive.
Thanks, that's great
You're the type of guy I'd love to bring on a road trip because I'm always wondering how cool rocks ended up that way.
Wow, that was truely fascinating. I will never walk my local Auckland beach again without stopping to admire and contemplate the cliff formations. Wish you were my 3rd form teacher back in the 90's!
Glad you enjoyed it
I live in Mairangi Bay, often walked past the cliffs. They look more stable than they really are. Since I arrived in Auckland in 1971 - ive also noticed 'Watchman Island' [a hunk of rock and some plants] close to the south side of the Harbour Bridge, getting smaller and smaller.
One day it will have eroded away.
LOL taking the human harbour bridge with it !! 😂
Yes the Waitemata Sandstone cliffs are eroding back at rates of about 1-5 m per century depending on exposure.
Enlightning explanation of folds, grain size orientation of up/down, etc. Anticlines, syncline explanaton brought back memories of when I took geology in Pasadena, CA, with San Andreas Fault nearby. Howhere at that time the theory of plate tectonics had not been elcidated..... it's been an exciting ride as science provided explanations. And now in 2017 a new continent Zealandia!
Thanks for your comment!
So interesting, I spent lots of time walking round Stanmore bay cliffs. Thanks
That's great!
I'm a glider pilot and it's always great to see the countryside from above (sometimes not very above), while having it explained like this helps complete an overall picture.
That must be great!
Thanks for covering this. I grew up in Point Chevalier, Auckland. The whole "Point" is surrounded by coastal cliffs just like those you showed at Stanmore Bay. (Where I holidayed in my childhood in the late 50s/early 60s.) This geology is so familiar to me, but not its origin. I used to try and see if I could find and break out the largest pieces of those thinner red layers, which were shown but not specifically mentioned.
Thanks for your comment
Super interesting. Dad has a place in Waiwera, and i asked him about the rocks at Waiwera Beach, but he is a boat builder and boiler maker not a geologist, so he wasn't able to go into as much detail. 25 years later and a video about similar rocks not far down the coast explains it beautifully.
great video, you make this much easier to understand when I look at those layers
Cheers!
This is my childhood stomping ground, so many summers spent hopping between rocks at the base of these cliffs and scrambling up amongst the pohutukawa and flax clinging to the steep sides. The fragility of this land is remarkable, seeing the way an entire hillside slips away makes me doubt the supposed antiquity of the layers. The earthquake faults stand as testament to the violent past of this green land. And what about the weirdly deep layers that are just an amalgam of everything - like a tsunami of mud has been deposited all at once.....makes you wonder.
Petrology, sedimentology, plate tectonics, weathering and erosion. I first learned about these sciences at school 55 years ago and very valuable they have been too (as a professional archaeologist), in helping to differentiate between archaeological and geological topographical features. Especially in the UK, where such phenomenon can be confusing. Having said that, I'd love to examine your very own Kaimanawa Wall for myself, one day.
Enjoyed the video! We were running along the coast from Long Bay to Takapuna. Great to imagine the geological processes that went on over the years!
Thank you!
Outstanding I'll head over the bridge and take a look. Love the explanation of how the larger coarse aggregates fall out of suspension first and you can re orientate good old what's up, and what was down. It always tells a story . I've read a few books, but your efforts have brought it to life, so thank you and keep the videos coming as I have subscribed . Regards Kris
Thank you, glad you enjoyed the video
Absolutely love Dr Hayward's teaching style. something about his enthusiasm really captivates my attention; without any pretension or grandeur he's revealing a legible record of history hidden in the illegible mess of rocks and dirt. a true "science communicator." Neil DeGrasse Tyson ain't got nothing on Bruce Hayward!
Indeed!
Awesome video. Would like to see more about NZ above and below water.
Thank you so much. This is brilliant. I 😂pull love to see a video about the geology of mangawhai and the volcanoes around there, the lava collums and how the white sands got there from the waitako river through the Thames way back.
Another one for the list 🙂
Amazing! I always wondered about these cliffs
Thanks for sharing. Will have a different respect for the cliffs as I walk the bays now. Interesting stuff! Glad I found this
Great!
Great stuff! Now I know. 🤔
Thank you.
Such an interesting series of videos, keep them coming
Thanks!
Thanks Bruce, l really appreciate you and your team explaining the geology we see around us. Great work! There are interesting folds in the cliffs around Castor Bay that I had assumed were caused by the Lake Pupuke volcano, but I can see now that they would have been there before it.
Thanks for your appreciation!
So good! Thank you Bruce!
So very very interesting. Thanks Bruce.
Very welcome
Loving these. Keep it up.
Thank you!
Loved this so interesting thank you
Great!
Very interesting, thanks for sharing. 👍
Cheers!
Pretty sure i've heard these rocks referred to as "Waitemata chaos series" previously, due to the shear number of folds, faults and unusual beding planes :)
It's also worth mentioning (while only brushed on by the video) that the darker colours and large, angular cobbles are mostly "volcaniclastic" sediments and grits from the Northland volcanic arc; the dark colour is due to ash, scoria, pumice and basalt.
Thanks for your comments. Yes, we are hoping to make another video about the volcanic layers at some point.
Fabulous detailed information there. Thanks so much for that.
Cheers!
Awesome video! Cool to learn how to see the history of the land I grew up around
Cheers!
Amazing!
Glad you think so!
Really informative... this series on NZ geology is really fascinating. We live on the Shaky (foldy) isles indeed
Thanks for your appreciation!
Feb this year i was on the northern side of long bay reserve just south of stanmore bay. I noticed the different colored layers in the cliffs and wondered how long in the past I was looking at. Now I know 😃
Geology 101, thank you so much
Our pleasure
Beautiful geology. I enjoyed this excursion & lesson very much. There's some similar gravel & silt features here in Hawkes Bay, will be looking at them with a different eye now! I found some white clay with pumice in it, is that from Taupo or did it float there when the land was at sea level? 🤷🏻♀️
Depending on the geological age, quite likely from Taupo or another major volcano in the Taupo Volcanic Zone. Could perhaps also have come from one of the Kermadec volcanoes that occasionally erupt pumice
Thoroughly enjoyed this. Thank you 😊
Glad you enjoyed it!
That was facinating.
Thank you!
One area I find fascinating, geologically wise is when driving through the Awakino Gorge, that stretch of road that weaves through those high cliffs of different coloured rock. I always pull over and wonder about how it was formed. Ive tried finding information on line but theres not allot about it. The Waitomo CAves Museum has some good info but thats about it.
Great video as always!
I'd like to see a video about the Mohaka Fault - the northernmost extension of the Wellington Fault.
I'd like to know when it last ruptured and what the approximate average return-time is between its ruptures.
I'm also keen to know if it may have been a Mohaka Fault rupture that created Lake Waikaremoana (which was formed due to the creation of a landslide-dam - presumably created in a huge quake).
Thanks for your comment - another idea for the list!
I live on the Hibiscus coast! Thank you for sharing this with such knowledge and enthusiasm! You rock 🪨 ;)
(pun intended)!
Cheers!
Very similar to the eastern side of Buckland's Beach peninsula, almost identical.
Great video.
this is mind-blowing. cheers from avondale
Thanks for your appreciation!
See the load casts in the bed to left also at 4:26
Just went to Kawhia and saw diagonally slanted cliffs at albatross point. Thanks for the explanation.
Cheers man, that was really interesting.
Glad you enjoyed it
Thank you this is so very informative l love these videos about my nz my country 😊
Best place for me to see these folds is low tide at Scott’s Landing Mahurangi. We were there today very few people you walk over to the island across the beach and it’s the rock between the island and beach that is the layer. You actually walk on what should be a cliff.
Fascinating, thank you very much for the education. I felt like I was back at high school or uni with an excellent teacher or lecturer. 10/10. Will try to visit that double fold at some point soon. :-)
So good!
I recognized the beach from very first frame,my favorite beach on the hbc,my dad lived just up the rd
One of my favourite drives was from Waikeretu north to Port Waikato. At Waikertu there are these layered rocks I guess formed by layers of marine deposition. Further north there are what I think are collapsed (Limestone?) sinkholes that form these large 'ampitheater' like structures. Closer to Port Waitako you can see these rounded almost spherical bubbles in the cliffs, limestone erosion perhaps? I ran off the road into a ditch and asked a local farmer to tractor me out & he asked me what I was doing there. I mentioned the rock formations and said 'oh so your a geolgist then?', No sorry just a bewildered amateur. I would love some explanation of what I saw on my drives.
Yes that part of the country has layered deep-water sandstone and mudstone deposited about 20 million years ago overlying limestones that accumulated as shell banks in shallow water about 30 million years ago, when there was very little eroding land to supply mud or sand to the sea. The shell banks were recrystallised and hardened by circulating groundwater and burial into the limestone.
What kind of events would cause such a dramatic change in geological structure? E.g earthquake? or is this just constantly happening under our feet without us noticing?
Turbidity currents can be triggered by earthquake shaking or by major storms on land bringing down vast quantities of sediment. The 2016 Kaikoura Earthquake triggered turbidity currents down 10 submarine canyons off the coast between Kaikoura and the Wairarapa.
great stuff mate
🙂 Ta
Hello awesome information on our beautiful Country. Am just wondering if you might get a chance to talk about Great Barrier Island. Please. Thank you.
Can add it to the list for one day...
@@OutThereLearning 😁
Does the varying thickness of the sandsones give us any information about the depostional environment? Or is the thickness just a random feature of the flow path?
The turbidity currents came down submarine canyons and on reaching the floor of the basin they spread out to build up a submarine fan of sediment with distributary channels like a delta. The thickness of the sand layers deposited depended on how large the turbidity current was and whether the sand was deposited in a channel (thicker) or overbank on the submarine levee (thinner and finer). Coarser and thicker deposits were also often deposited closer to the mouth of the canyon and thinner and finer further away.
Bloody neat alright…😎
Very interesting to me. I have spent quite a bit of time observing and pondering that coastal area. Great to have some real analysis and time frames to add.. Do you have any ideas about the volcanic scoria conglomerate (or as you would more properly call them) that you see as layers in those cliffs? I think I have seen meter plus thick layers at Army bay and Wenderholme and possibly seen more widely. Its been a few years since I lived in the district but I remember wondering about where the volcanics would have come from.
How do the grains of sand in the sand stone stick together? If i filled a bucket with sand, turned it over, removed the bucket and then poured water on the sand, it would be easily eroded. Why hasn't the sandstone been eroded?
Great question. They were compacted and cemented together over millions of years due to squeezing under the compression of hundreds of metres of overlying sediment. That overlying material that put them under such massive pressure has now eroded away to reveal these rocks.
Sandstone grains are held together by a cement of some sort....the cement is deposited from mineral rich pore fluids that circulate through the compacting sediment during burial (a process known as diagenesis). Common cements are silica, calcium carbonate and iron oxides.
Hello Dr. Bruce! I'm currently in Auckland for a short course at UoA. One thing I noticed when I was in the plane was the linear features at the western coast of the North Island. Is there any reason why this is almost perfectly straight for hundreds of kilometers? I quickly checked the geology around the area and I haven't seen any NW trending faults in the area.
Love your videos, by the way!
If you are referring to the actual coastline being straight, then the reason is the oversupply of sand in the coastal system on that coast over the past 2 myrs. During interglacial high stands of the sea the excess sand has been thrown up as beaches, sandspits and sand dune barriers across most of the indentations that were valleys eroded to a lower base level when sea level was lower.
@@BruceHayward1 West coast is pretty amazing. You can see geology happening in real time in the sand dunes that form the ever-shifting western edge of our nation!
@@BruceHayward1 hello Dr. Bruce. Apologies, I didn't realize I was not able to reply to your response. Thank you for answering my question.
Thoroughly enjoyed my stay in New Zealand. Thank you for your videos!
That fold is how Dali would paint a landscape.
Thank you so much for explaining these beautiful folds and bends in the landscape. Isn't nature powerful!!!
True!
Great video.
New subscriber here!
Cheers!
Petrified wood of ancient giant trees 💚
What is the age of the stone that you are standing on thanks
About 20 million years.
You’re a genius.😊
hi just found you , great video . just a thought , i'm a Aussie , if you know that the same thing is here , please let us Aussies know where to look. it makes it far more understandable . and i have seen similar formations here but lol can't remember now were they are . keep up the good work , i also subscribed . THANKS
Is it the same as in the northern manukau?
Yes same strata form the cliffs on north coast of Manukau Harbour.
I liked the part about the frakcha.
:-)
I saw what I thought was pancake eroded lave columns at Pukekiwiriki today, but after watching this I can see that they must be uplifted marine sedimentary rock. That'll be why the crater is over the hill.
A question please - wasn't there once a mighty meteor impact in the south Indian Ocean, that sent massive tsunami waves across the Tasman? Collided with Northland, rolled straight over it?
Created 90 mile beach?
I think there were also earthquakes and eruptions from the Kermadics that would have rolled straight into the Hauraki Gulf and surrounding cliffs?
A turbulent history in these islands ...
All sorts of ideas here - some true, some myth and none to do with the features in the far far older Waitemata Sandstones featured in this video. 90 Mile Beach and the giant tombolo of Aupouri Peninsula behind was made by the slow accumulation of sand carried here by rivers and longshore drift from eruptions in the centre of the North Island.
No tsunami in the world would be large enough to flow right over Northland.
Yes a few submarine volcanic eruptions on the Kermadec Arc are understood to have generated up to 20 m high tsunamis that flowed up on the east coast of Northland and Great Barrier - the most recent several thousand years ago.
@@BruceHayward1 Thank you so much for your informative and interesting post Mr Hayward : ) I had to immediately look up what a 'tombolo' was in Wikipedia : 0 and also learned that it is possible for accumulations to build up over all that geological time required. Thanks for clarification that "no tsunami in the world could flow right over Northland" because I was told that this happened, by a Northlander, to explain the straight and long shape of the Aupouri Peninsula !!! Before the Internet was even thought of..... that is how myths and legends begin : )
Dress shirt and stubbies, i love it.
🙂
Theres some o f these in thej kaipara on little islands they kind of look like trees up home but theyrem definitely these😂
What is the speed of erosion on the 800 m of stone above that eroded?
The 800 m has been eroded off since being uplifted about 15-18 million years ago. Cliff retreat at the moment is about 1-5 m per century,
When I heard your voice I thought you might have been Te Radar's (Andrew Lumsden) Uncle or at least from the same area where he grew up.
Found a coal branch in one of those cliffs, haven't found one since
It may be worth emphasising that the deformation of this sandstone was due to gravity slide/slump, not compressive tectonic deformation.
Absolutely. Maybe it is a bit far into the video at 8:40 where I talk about the submarine slide origin of the folds.
Hertled up down at speed more than 2,3km at heat as well from looks off it
2:34 10cm per 1000 years
How long 2m mudstone?
20.000years? Really?
Maybe 200.000?
Mud on the ocean floor accumulates at different rates depending on the distance from river mouths carrying suspended mud and submarine canyons with suspended mud turbidite tails. 10 cm per 1000 yrs is the rate measured over the last 1 million years from a deep-sea core (DSDP 594) at 1200 m depth, 200 km offshore of the major east coast rivers draining the Southern Alps in Canterbury Bight. This hemipelagic mud is a good analogue for the Waitemata Basin.
Dam Say the place names right
Thanks for your feedback
How much of this is speculation?
Thanks for your question. Hopefully you can tell that years of evidence based research by a lot of people has gone into building up the understanding of these rocks and the processes that created them. Cheers
This word rang in my head as I watched the video. An earnest contribution, for sure, but incredulous as an engineering explanation of nature.