Teacher should be forced to purchase high-quality recording equipment for their lectures. Students pay a damn fortune for the education and have to sit there and listen to that crackling nonsense of a 1990s microphone. It’s completely unacceptable.
My biggest objection to the theories stated here are the assumptions by geologists, and others, that "everything has alwats been the same". I doubt North America looked like it does today as recently as 10,000 years ago. It could be significantly less than that. What we see, today, is "where everything ended up", during the most recent set of catastrophic influences that affected positioning, and placement. That these events are not considered renders null much theorizing, because you are only grasping the "tail" of the "elephant" (see the parable of the "Six Blind Indian Fakirs Describing an Elephant to the Rajah"). The Grand Canyon was "carved" by massive amounts of water (I estimate a half-trillion acre-feet of water, sent suddenly westward, about 4,250 years ago). Some of that water joined the puddle of water already there, and did the rest of the damage. Oh, and Earth has not always had "oceans". Seas, large lakes, yes, but oceans, nope. It might have had one, but one Plate Tectonics theorizer shows the "Pacific Plate" as a tiny piece surrounded by now-missing plates, in the middle of the area the Pacific Ocean covers. These "seas" were relatively shallow, perhaps a matter of hundreds of feet deep, at most. Later events would pit the plates against one another, causing depressions, to allow water to drain off the "continents", into the gathering Oceans. The "Great Unconformity" was the result of some of this "tectonic" activity, when one plate was shoved against another, separating it into layers, pushing one layer, more hardened that others, over those nearby. What we have, as a result, is "over-intellectualization", caused by blindly accepting theories, despite clear evidence other things happened, more recently, more devastatingly, and more incisively. The ancient past is as murky, ill-defined, and misperceived, as ever. Why do "professionals" persist in ignoring the anecdotal evidence of catastrophism, in favor of crackpot theories about long, long, long ago? No doubt, a great many things happened over the four-point-five billion years of Earth's existence, but the Earth we know and love is a relatively recent creation, looking very little like the Earth our most-distant ancestors knew. The Appalachian Mountains were "attached" to the ONAC a long time ago, but the Rockies, Sierras, and other western ranges are vastly younger. Oh, and the big question, the "$64,000 question", as it were, is as plain as the nose on your face: What caused the plates to do the things you describe? What caused them to not only "move", but CRASH INTO others, with great force? I suspect the Rockies, alone, weigh in the range of quadrillions of tons. What would it take, to push them, until their peaks top out at 14,000 feet above mean sea level? Think carefully of your answer, because the follow-up question is even harder. Why haven't these things taken place, in the last 2,750 years? I mean, yeah, Krakatoa, the 2004 tsunami, the 2011 tsunami, but nothing moved on the map, with those, or any of the Earth's other hard points. If your theory is that Earth went through a prolonged siege of attempted self-destruction, I hope you realize how self-serving that kind of answer is. I believe the story is far more personal, to humans, far more violent, and totally caused by an extraterrestrial force. One that is still tidally-locked with Earth, some millennia later, for, yep, you guessed it, two thousand, seven hundred fifty years. Oh, and Florida, around to the Yucatan, including Cuba, the Bahamas, and the eastern flanks of the Sierra Madres, are even newer additions to the "continent".
Useful additional context could be gained by showing the Equator on each of these maps. So we don't get left with the impression that the Laurentian craton has always been around the same latitudes.
Lame that this lecture fails to expand on the youngest and very interesting geology of Oregon and Washington. The flood basalts and high cascades, the clockwise rotation, and many other things from the youngest part of North America.
Utterly fascinating. So glad to have found this. I have been searching around for a good few years, for videos about the geology of this area, and coastal or continental shelf areas of Asia. Also about Mongolia and Siberia. That is - areas that are NOT part of the Tibet tectonics story. I'm intrigued about what is occurring where the Asia plate has its eastern edge and where the North American plate meets the Eurasian one - especially what is going on in northern Siberia or the waters north of Siberia. This video may "only" discuss a small area. But, as my great grandmother used to say, "Small. But so's a stick of dynamite."
I work miocene tectonics of central chile for metallogenic processes. I work near a plate fold. You come so close to metallogenic processes. I find them worth considering. You should play around with metallogenic tectonics. I think you will do a good job. There is a lot of work in the Andes.
I’m so glad this work solves the societal problems we have like the housing crisis. Great work man. Keep on wasting money and time. Lots to spare these days. Not like war is all around us
As a 'hobby geology enthusiast' from BC, I loved this lecture. Lots of pausing & digesting needed, but my spacebar survived. Thank you very much for making this lecture publicly available.
Excellent presentation of a fascinating subject. I was tempted to go into geology, but mainly for oil exploration. Anyway at that time plate tectonics, then called continental drift, was not taken seriously by geologists who were interested in maintaining their professional status because the idea was proposed by a meteorologist, and what do they know about rocks...
The heat flow map of the globe is interesting in that the highest heat flow areas(orange and red)are in the southern hemisphere. Is this a projection artifact?
I'm not a pro, but i do live in a region where this is hapening, (Siletzia), and its very interesting to see the model, and how the parts fit and how the numbers relate. In some ways it's reminicent of how SiO2 deforms on a field effect transistor's "bird beak", but the scales are vastly different.
Per your last slide on exotic fault plane materials, wouldn’t Byerlee’s experimental data have included these? I still have an intuitive problem with low angle slip that you explain quite well with graphs in this episode. Unlike compressional regimes, in extension the earth is being opened up, creating ever increasing avenues for pore pressure escape, can’t imagine how these faults get pumped up. How about multiple episodes of normal faults, rotating earlier generations to low angles? Perhaps this model has been discounted after 30yrs since I looked last at this.
The Whipples are amazing, went out there with Eric Frost in the early 90’s. In those years debate on low angle faults and their ability to slip at that orientation was raging. I still have a hard time reconciling slip at low angles…
I'm curious. Would there have been any oregenic events between the acreted Protopaleozoic blocks in green. Soecifically between the Yavapia and the Mataztal. I'm currently sitting just about on the border for that in SE Wisconsin
This makes it sound like we've got the cordillera all sorted out. 😅 There's some interesting evidence for a period of _westward_ subduction. Also, there are proposals that the Laramide orogeny results from accretion and "hit and run" northward translation of some large archipelago or "ribbon continent" -- rejecting the flat subduction explanation pretty much entirely, as far as I can tell. And the accretion of Siletizia doesn't even rate in an overview this broad, eh.
This is a very general overview intended for an undergraduate audience in Europe, so it is indeed quite simplified and doesn't have the length/scope to present all alternative hypotheses. Still lots left to sort out in the Cordillera, no question!
Thank you for this very informative video. As an untrained geology hobbyist, I'm sure it will take several viewings to unpack all the information contained here. However, as a Utah resident, there is one error that jumped out at me. At about the 22:38 mark in the video you present a slide of "the Wave" and identify it as being located in Zion National Park, which is incorrect. The Wave is actually located in the Vermillion Cliffs National Monument in northern Arizona, about 90 km ESE of Zion NP. Nit-picky...I know. ;) Thanks again for helping me better understand the geology of my home state. :)
I am fascinated by the age, size and location of Appalachian Mountains, Pangean Mountains. People have no idea where you can still find them, nor how huge they were.
While I realize a lot of work has been done on the geologic origins of California, I feel like California is an incomplete stand-in for all of Western North America and doesn't represent the origins of the Pacific NW and the current issues with the geologic origins there, particularly the paleomagnetic data.
True, the PNW and also southern AK have different histories from CA and this lecture is southwest-Cordillera-focused so as to include the San Andreas Fault system.
Excellent lecture. So much information here, necessitating several pauses and review! I had no idea the San Andreas was due to ridge subduction. Thank you for a more comprehensive understanding of the rich history of my home continent. As an autodidact geologist I applaud the bounty of teaching made available to the public by scholars like yourself. Be proud of the online legacy you leave!
Very good summary. Well illustrated. Note: The Wave is NOT in Zion National Park, Utah. It is further east, in the Vermillion Cliffs National Monument, Arizona. (36.99606987678976, -112.00630071063867)
