Please be sure to LIKE and SUBSCRIBE. You can support my educational videos by clicking on the "Thanks" button just above (right of Like button) or by going here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
I’m always excited when you put out another lecture video. My dad served in the navy around the Marianas, so it somehow seems more personal to learn how those ultra deep ocean trenches formed. Thanks from Minnesota!
Shawn there has been much discussion about the so called lost continent of Zealandia in which case a large land mass has submerged deeply. It seems counter intuitive to lose a land mass rather building up more land like the Aleutian islands unless the ocean floor is sinking. Great thing for me to ponder I guess. Thanks for your online course.
The series is sooo interesting! Just the right way for me to learn slowly, because I am an absolute newbie ;-) to geology. Wonderful and thank you for this!
Found in an article pn a noaa web site about Mariana trench: "There are so many exciting geological features within the Mariana region, the area is like an amusement park for geologists."
I’m trying to catch up on Geo 101 after traveling a lot, so I’m watching this a month after the release. What a great USGS map! Love maps. Just want to say thank you!! I love learning, and your geology videos are very appreciated. 😊
There are a few places around the world where the direction of subduction changes over a relatively short distance. Why? (Credit to Kiwi geology channels raising my awareness of this.) The sudden-transition area seems particularly messy.
Question: the Cascades were mentioned as an example of a subduction zone, something I was already aware of. But from the various maps shown on here, they really don't look all that similar. They share the clear trait of volcanism, but there's no clear trench on Google Earth, and the earthquake pattern doesn't match the others at all. Can you speak a little more on what makes them different from these other examples? (It might not fit into the Geo 101 series, but it's something I've never seen a compelling explanation of)
At 19:00 the video for continent-continent collision, the mountains formed are labeled "volcanic arc". Shouldn't this be something like "high mountains"?
Sorry to be that problem student that asks a lot of questions🙂 With all the plates moving around, is there not some torsion/torque forces near re north pole with all the plates south of it moving around? how come the north pole doesn't have lots of erthquakes and volcaoes (especially as the earth's diametre is smaller there). ?
Note that the main 4 islands of Japan are actually a continental oceanic convergence zone where a mature back arc basin has pulled the coast of Eurasia with it out to sea. Other parts of the Japanese archipelago are oceanic in origin but the 4 major islands of Japan are not. Frankly the geology of Japan is so complicated with at least 5 different tectonic plates; the Amur, the Okhotsk(former piece of North America), the Eurasian, the Philippian and the Pacific plates respectively, with every single kind of convergent plate boundary occurring in some shape or form within that tectonic mash up, that I would probably have just avoided bringing it up in a geology 101 lecture. I mean I know no subduction zone is as simple as those models of idealized subduction project but you still don't need to jump in with the hardest example first!
Is the India plate still pushing against Tibet? If so, is this why we have such a hardtime getting exact altitude of the Everest summit because it keeps changing? (or are plate movements so slow that Everest's top would not have seen any appreciable change in last 100 years and the ever changing altitude of Everest is simply a measurement/instrument issue? ) Will there come a time where India will strike a deal with China and will stop pushing agaisnt each other and live happily thereafter? or Is the force pushing India to the north stronger than any resistance offered by the eurasian plate and the conflict will persist until India has moved up to the north pole?
My questions: You say that when two oceanic plates converge, the older plate is the one that subducts and that is because the older plate is more dense. Am I correct in assuming that newly formed oceanic plates are of nearly equal density when formed? If so, would you please comment on the processes that cause the density of a plate to increase with age? On the other hand, if my assumption is wrong and the density of the plates do not increase with time, why were oceanic plates formed further in the past more dense than those formed more recently?
On the big USGS map, Hawaii is right smack in the middle of the Pacific plate with no plate boundaries anywhere near it. How come it is such an active volcanic/seismic zone? Is this unique for the planet or are there other such sites not near a plate boundary?
I'm a lay person, so take what I say with a grain of salt, but I believe the reason Hawaii has volcanos is because it is located over a hot spot, similar to the one in Yellowstone. Hotspots don't "move" but the plates overlying them do. That's why the ancient "Yellowstone Hot Spot calderas" stretch across Southern Idaho and into Nevada (at least).
Thank you, Shawn, your teaching style really pulls me in and I learn something new every time, often many points. I look forward to these classes and can hardly wait for the next one. You stretch my 66 year old brain and I love the exercise.
Excellent class. I so do look forward to these. And, I ordered the map for my studio ( $9.00 in US, probably cost a mint to laminate it. lol) . Cheers!!
Excellent episode! Thank you again for doing this, Shawn! I know so little and I'm learning so much :) Love the USGS Dynamic Planet map, thanks for the link! Enjoy your cruise on the Rhine :)
Loved this clear explanation of all the three possibilities and with those maps. Books don't do much justice with explaining these things clearly and leave some doubts. Really appreciate this presentation ❤
Very interesting. When I studied geology in the 70s we mostly learned about geosynclines. Plate tectonics were relatively new and while they were included in the curriculum, I love seeing the advancement of knowledge. I grew-up 30 miles east of L.A. My mountains run east and west (including an ancient volcano core) with the high desert plateau to the north of them, so the continental-oceanic convergence says the ocean should be to my south, but it isn't. It's to the west. The slip-strike San Andres runs through the Cajon Pass to my east, so...??? This is going to keep me awake all night. When is Episode #5 coming out?
I'm so grateful for this education! A great investment from your side, knowing not as many people will whatch it for education that we can be thankful for! ❤
Greetings from the convergence zone of 3 major fault systems, the San Francisco Bay area. We have the San Andreas, the Hayward, and Calaveras Fault Zones, all capable of up to magnitude 8 quakes. Our San Jose soccer team is named the Earthquakes. The Calaveras creeps along though constantly, witness thevtown of Hollister being slowly torn in half along with some houses built right on top of the active trace! Went nearly crazy trying to figure out the Franciscan Melange which dominates the California coast, a real mish mash thar doesn'T make a lot of sense and despite being marine, contains scarce fossils. I had read that these are the accumulated marine sediments that had piled up at the toe of an ancient subduction zone hence the strange mix of stuff along with huge turbidite deposits. We are all loaded for bear here for quakes; gotta be prepared. Thanks for the videos, never tire of the Earth.
Question: I don’t understand why “C” is correct. To me, that diagram looks like there are no earthquakes on one side of the plate boundary, yet your drawing shows x’s on both sides . Which side of the boundary has no quakes? The overriding one or the subducted one? Thank you.
Hello and greetings Shawn from Kanab Utah ... Probably one of the most interesting and potentially significant geologic events in our lifetime is Campi Flegrei in Italy. If TPTB have instructed you to avoid this place, please just say "No Comment". I will understand your predicament. Respectfully, Utah Mike.
@@Dan_Neely Hello Dan 🖐... If I was a professional geologist I would probably choose not to discuss the situation that is developing at Campi Flegrei. It is very likely going to have some degree of eruption. Discussing the current threat levels will not change the outcome for those that do not recognize the danger and move away now. Shawn will have plenty of opportunity to discuss this area of the world if and when an eruption does occur. Respectfully, Utah Mike. 🙏
Around 4:00, you explain that the older oceanic plate subducts under the younger one because it's denser. Why is older basalt denser? Is it because basalt that is made at divergent boundaries today is less dense than the basalt that was made millions of years ago? (If so, why?) or because something happens as basalt ages that increases its density? (If so, what?) And, in either scenario, won't the age relationship eventually flip? Assuming the subducting plate is being destroyed faster than the other one, won't we eventually end up with the subducting plate being younger? Its rock at the point of subduction should be of roughly constant age, determined by the distance from the divergent boundary where it was created and the speed at which it's moving. But the rock in the non-subducting plate is getting older and older -- so eventually it'll be older, right?
Older basalt in oceanic plates is denser because it is colder. The water temperature in depths of several kilometers below sealevel is barely above the freezing point and the longer the oceanic crust is exposed to these low temperatures the more it cools down. Colder material is nearly always denser, not only with stone but for instance also with metals (except for some exotic alloys). Also the rocks had more time to settle and be compressed by the weight of the water above it.
@@7inrain That doesn't sound right. Materials are only denser when cold because they contract. Rock doesn't contract very much at all, and we're only talking a difference of about 10-30C between the land surface and the ocean floor. Also, water is very light compared to rock, so oceanic crust is compressed much less by a kilometer of water above it than continental crust is by a kilometer of rock.
@@beeble2003 OK, I've read a few papers now. It seems the main contributor to older crust being denser is that it is getting less and less porous. When basalt is forming at the mid-ocean ridges it is very porous, leading to densities far below the mean density of oceanic crust which is at 2,900 kg/m^3. Freshly formed basalt can have densities of only 2,270 - 2,500 kg/m^3. So in fact compression over age is the main factor, both by the weight of the water above it and by the weight of the basalt itself when comprised in a layer with several kilometers of thickness.
Picture pulling on a really long Slinky. You can eventually drag the whole thing along but the entire thing won't move at once. I hope that's sort of accurate.
Please be sure to LIKE and SUBSCRIBE. You can support my educational videos by clicking on the "Thanks" button just above (right of Like button) or by going here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
Thanks Shawn. Couldn't really see the colours in that quiz on a small screen, but your explanation clarified things for me.
Love when a new Geology 101 video goes up. Does anyone else get the feeling Shawn is the professor everyone wants to get at his school?
With Shawn, you can feel how his desire is to make you understand. That is what makes a great teacher. And that he is!
Shawn makes learning interesting and fun!
Yes...ME! 😂
I’m always excited when you put out another lecture video. My dad served in the navy around the Marianas, so it somehow seems more personal to learn how those ultra deep ocean trenches formed. Thanks from Minnesota!
Hey Shawn, great series! Thank you so much! Putting this video into the 101 playlist would make it easier for others to find it 👍
Shawn there has been much discussion about the so called lost continent of Zealandia in which case a large land mass has submerged deeply. It seems counter intuitive to lose a land mass rather building up more land like the Aleutian islands unless the ocean floor is sinking. Great thing for me to ponder I guess. Thanks for your online course.
Thank you for sharing this and I’m looking forward to that deeper dive into plate tectonics! With volcanism my favourite geo subject 😊
Thank you Shawn.
The series is sooo interesting! Just the right way for me to learn slowly, because I am an absolute newbie ;-) to geology. Wonderful and thank you for this!
Good Morning. Love the classes. Sugar Land Texas
Found in an article pn a noaa web site about Mariana trench:
"There are so many exciting geological features within the Mariana region, the area is like an amusement park for geologists."
I’m trying to catch up on Geo 101 after traveling a lot, so I’m watching this a month after the release. What a great USGS map! Love maps. Just want to say thank you!! I love learning, and your geology videos are very appreciated. 😊
I may be 71 years old but I was so thrilled to get the correct answer 😃 Thanks Shawn.
Thank you Professor
Super lecture, thank you.
Loved it. Learnt loads.
Di…Cumbria.
Thanks for a great revision lecture, Shawn. I wish I’d had these maps an animations when I was doing my degree 🙂.
Thank you Shawn , It looks like many Red Dots Man , Prayers .
Thanks again, Professor!
Thank you!
Good morning from Santa Monica CA 🌴
Thanks
There are a few places around the world where the direction of subduction changes over a relatively short distance. Why? (Credit to Kiwi geology channels raising my awareness of this.) The sudden-transition area seems particularly messy.
Question: the Cascades were mentioned as an example of a subduction zone, something I was already aware of. But from the various maps shown on here, they really don't look all that similar. They share the clear trait of volcanism, but there's no clear trench on Google Earth, and the earthquake pattern doesn't match the others at all. Can you speak a little more on what makes them different from these other examples? (It might not fit into the Geo 101 series, but it's something I've never seen a compelling explanation of)
I need help with a subtraction zone were 1 mtns was split apart from volcanic action
When u look at Scotland, it is almost divided in two by those lakes, one being Loch Ness. Is that a divergent or convergent plate boundary?
How do the Deccan traps fit in with the India/Asia collision, if at all?
At 19:00 the video for continent-continent collision, the mountains formed are labeled "volcanic arc". Shouldn't this be something like "high mountains"?
Sorry to be that problem student that asks a lot of questions🙂 With all the plates moving around, is there not some torsion/torque forces near re north pole with all the plates south of it moving around? how come the north pole doesn't have lots of erthquakes and volcaoes (especially as the earth's diametre is smaller there). ?
Note that the main 4 islands of Japan are actually a continental oceanic convergence zone where a mature back arc basin has pulled the coast of Eurasia with it out to sea. Other parts of the Japanese archipelago are oceanic in origin but the 4 major islands of Japan are not. Frankly the geology of Japan is so complicated with at least 5 different tectonic plates; the Amur, the Okhotsk(former piece of North America), the Eurasian, the Philippian and the Pacific plates respectively, with every single kind of convergent plate boundary occurring in some shape or form within that tectonic mash up, that I would probably have just avoided bringing it up in a geology 101 lecture.
I mean I know no subduction zone is as simple as those models of idealized subduction project but you still don't need to jump in with the hardest example first!
Is the India plate still pushing against Tibet? If so, is this why we have such a hardtime getting exact altitude of the Everest summit because it keeps changing? (or are plate movements so slow that Everest's top would not have seen any appreciable change in last 100 years and the ever changing altitude of Everest is simply a measurement/instrument issue? )
Will there come a time where India will strike a deal with China and will stop pushing agaisnt each other and live happily thereafter? or Is the force pushing India to the north stronger than any resistance offered by the eurasian plate and the conflict will persist until India has moved up to the north pole?
Can you share the .SKP or KMZ files on your new website pls?
My questions: You say that when two oceanic plates converge, the older plate is the one that subducts and that is because the older plate is more dense. Am I correct in assuming that newly formed oceanic plates are of nearly equal density when formed? If so, would you please comment on the processes that cause the density of a plate to increase with age? On the other hand, if my assumption is wrong and the density of the plates do not increase with time, why were oceanic plates formed further in the past more dense than those formed more recently?
On the big USGS map, Hawaii is right smack in the middle of the Pacific plate with no plate boundaries anywhere near it. How come it is such an active volcanic/seismic zone? Is this unique for the planet or are there other such sites not near a plate boundary?
I'm a lay person, so take what I say with a grain of salt, but I believe the reason Hawaii has volcanos is because it is located over a hot spot, similar to the one in Yellowstone. Hotspots don't "move" but the plates overlying them do. That's why the ancient "Yellowstone Hot Spot calderas" stretch across Southern Idaho and into Nevada (at least).
@@davidk7324 Thanks. Guess I'll have to wait for the lesson on hot spots 🙂
Do you want to help me out or are you too busy
I’m 65 but it’s never too late to learn! Thank you Professor!
I'm learning so much Shawn. You makes it all so clear and logical. Thank you.
Thank you, Shawn, your teaching style really pulls me in and I learn something new every time, often many points. I look forward to these classes and can hardly wait for the next one. You stretch my 66 year old brain and I love the exercise.
Great episode.. I’m really enjoying these so informative thank you Shawn and enjoy your holiday
Thank you! Very clearly explained. Happy to have passed the quiz. 😁
Excellent class. I so do look forward to these. And, I ordered the map for my studio ( $9.00 in US, probably cost a mint to laminate it. lol) . Cheers!!
Thank you so much Shawn very interesting leaning lots new information
Excellent episode! Thank you again for doing this, Shawn! I know so little and I'm learning so much :) Love the USGS Dynamic Planet map, thanks for the link! Enjoy your cruise on the Rhine :)
Loved this clear explanation of all the three possibilities and with those maps. Books don't do much justice with explaining these things clearly and leave some doubts. Really appreciate this presentation ❤
Glad you enjoyed it!
Thanks Shawn! Another great lesson!
I love this! It's so exciting! And I got the answer right this time.🤩
Thanks!
The BEST! Thank you so very much.
Very interesting. When I studied geology in the 70s we mostly learned about geosynclines. Plate tectonics were relatively new and while they were included in the curriculum, I love seeing the advancement of knowledge. I grew-up 30 miles east of L.A. My mountains run east and west (including an ancient volcano core) with the high desert plateau to the north of them, so the continental-oceanic convergence says the ocean should be to my south, but it isn't. It's to the west. The slip-strike San Andres runs through the Cajon Pass to my east, so...??? This is going to keep me awake all night. When is Episode #5 coming out?
I'm so grateful for this education! A great investment from your side, knowing not as many people will whatch it for education that we can be thankful for! ❤
Greetings from the convergence zone of 3 major fault systems, the San Francisco Bay area. We have the San Andreas, the Hayward, and Calaveras Fault Zones, all capable of up to magnitude 8 quakes. Our San Jose soccer team is named the Earthquakes. The Calaveras creeps along though constantly, witness thevtown of Hollister being slowly torn in half along with some houses built right on top of the active trace! Went nearly crazy trying to figure out the Franciscan Melange which dominates the California coast, a real mish mash thar doesn'T make a lot of sense and despite being marine, contains scarce fossils. I had read that these are the accumulated marine sediments that had piled up at the toe of an ancient subduction zone hence the strange mix of stuff along with huge turbidite deposits. We are all loaded for bear here for quakes; gotta be prepared. Thanks for the videos, never tire of the Earth.
Question: I don’t understand why “C” is correct. To me, that diagram looks like there are no earthquakes on one side of the plate boundary, yet your drawing shows x’s on both sides . Which side of the boundary has no quakes? The overriding one or the subducted one? Thank you.
Love this series!
I believe at 25:36 the red triangles actually represent active volcanos instead of earthquakes.
Thank you again for the informative lesson! Finally got an answer right😁
please recommend a textbook on tectonics (high acedemic level is fine)
A true pleasure. Thank you.
I do really love these lessons!! Everything is soo well and easy explained to an old beginner as me (61) Thank You soo much Professor!! 🤗👍👨🏫
You're very welcome!
👍
Hello and greetings Shawn from Kanab Utah ... Probably one of the most interesting and potentially significant geologic events in our lifetime is Campi Flegrei in Italy. If TPTB have instructed you to avoid this place, please just say "No Comment". I will understand your predicament. Respectfully, Utah Mike.
On other videos Shawn's said he doesn't have the time to keep up with other volcanoes beyond Iceland and Hawaii.
@@Dan_Neely Hello Dan 🖐... If I was a professional geologist I would probably choose not to discuss the situation that is developing at Campi Flegrei. It is very likely going to have some degree of eruption. Discussing the current threat levels will not change the outcome for those that do not recognize the danger and move away now. Shawn will have plenty of opportunity to discuss this area of the world if and when an eruption does occur. Respectfully, Utah Mike. 🙏
Around 4:00, you explain that the older oceanic plate subducts under the younger one because it's denser. Why is older basalt denser? Is it because basalt that is made at divergent boundaries today is less dense than the basalt that was made millions of years ago? (If so, why?) or because something happens as basalt ages that increases its density? (If so, what?)
And, in either scenario, won't the age relationship eventually flip? Assuming the subducting plate is being destroyed faster than the other one, won't we eventually end up with the subducting plate being younger? Its rock at the point of subduction should be of roughly constant age, determined by the distance from the divergent boundary where it was created and the speed at which it's moving. But the rock in the non-subducting plate is getting older and older -- so eventually it'll be older, right?
Older basalt in oceanic plates is denser because it is colder. The water temperature in depths of several kilometers below sealevel is barely above the freezing point and the longer the oceanic crust is exposed to these low temperatures the more it cools down. Colder material is nearly always denser, not only with stone but for instance also with metals (except for some exotic alloys).
Also the rocks had more time to settle and be compressed by the weight of the water above it.
@@7inrain That doesn't sound right. Materials are only denser when cold because they contract. Rock doesn't contract very much at all, and we're only talking a difference of about 10-30C between the land surface and the ocean floor. Also, water is very light compared to rock, so oceanic crust is compressed much less by a kilometer of water above it than continental crust is by a kilometer of rock.
@@beeble2003 OK, I've read a few papers now. It seems the main contributor to older crust being denser is that it is getting less and less porous. When basalt is forming at the mid-ocean ridges it is very porous, leading to densities far below the mean density of oceanic crust which is at 2,900 kg/m^3. Freshly formed basalt can have densities of only 2,270 - 2,500 kg/m^3. So in fact compression over age is the main factor, both by the weight of the water above it and by the weight of the basalt itself when comprised in a layer with several kilometers of thickness.
Has that San Andreas fault ever have a full rupture if not why not thank you
Picture pulling on a really long Slinky. You can eventually drag the whole thing along but the entire thing won't move at once. I hope that's sort of accurate.