The Alleghanian Orogeny
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- เผยแพร่เมื่อ 3 ส.ค. 2024
- Geologist Callan Bentley discusses late Paleozoic mountain building in Virginia - the collision of ancestral North America with ancestral Africa, closing the Iapetus Ocean and completing the assembly of the supercontinent Pangea.
It's incredible to hear that petrified trees in Arizona were buried by sediments from Appalachia! Mind blown!
Hello from southern Virginia! Love my home state and especially the very rural area I am from, I'm like a local historian for my town because my family has owned land and businesses here for many generations.. Although I could write a book on the bad things I think my state and town has adopted, I lack education on the reasons why the geology is the way it is. Such a great video. Thanks!
This is great, probably the "cleanest" description (sometimes cartoons serve their purpose) of how we arrived at the current formations around the Blue Ridge, to be fair I've heard bits and pieces of this story before but this helps tie my understanding together and will help me when I'm hiking sections including the AT and seeing greenstone, various Chilhowie formations and intrusive granite like at Old Rag Mountain.
I live in Eastern Pennsylvania and had learned that the Appalachians had been huge mountains at one time. Your discussion about their history has been extremely fascinating. Kudos for your knowledge and ability to teach such topics so that laypeople can easily understand and appreciate this information.
Outstanding lesson,very useful and well presented,thank you!
I'm so glad YT recommended your channel! Took lots of notes, got some words to look up now, lol! Wonderful graphics and imagery, too.
Well, I’ve been interested in how mountains form (and erode) for a long time, and this has been the best presentation of the subject so far. I even learned that my interest has a name: orogeny (from Greek “oros” mountain + “genesis” creation).
These videos make me wish I studied geology in college...
Thank you indeed. I used this video for Ph.D. students of Tectonics,in Collision Tectonics course, at the University of Isfahan. In this part of course,the Appalachians Orogeny was introduced.I'm waiting for your next videos.
Very well done because it is easily understood. I really relate to the great illustrations and diagrams.
Nice, quick presentation on the Appalachians. The only thing I would add is that some of us think gravity is the key to explaining Appalachian (and Himalayan) structure. During the collisions of Avalonia and Africa, subduction or "underplating" of contintntal crust thickened and (as a result of buoyancy) lifted up the "welt" and the overlying sediments that were originally the continental shelves. Uplifting and deformation of those sediments, and metamorphism of rocks caught up in the rising collision zone put stresses on them that exceeded their strength (just as is now happening in the Himalayas), and the "thrust" faults (actually huge gravity slides) moved off the uplift under their own weight. Those gravity slides formed what is now the Valley and Ridge and the Blue Ridge. As the effects of the collision died and the erosion of the orogen proceeded, the whole area "relaxed", with progressively decreasing uplift until buoyancy ceased to be a driving mechanism.
I think too many introductory geology texts overemphasize the idea of rocks shoving eath other around--if that's all that was involved, the deformation zones would be muich narrower. Unfortunately, the term "thrust fault" implies some things that aren't really realistic (at least for the huge, low angle ones), when you consider rock mechanics. Also, plate tectonics itself is a response to gravitational issues--oceanic "ridges" are actually big, broad uplifts (the one in the Atlantic takes up about 1/3 of the ocean basin), off of which new, "hot" oceanic lithosphere slides away from the uplift under its own weight (as do nearby continents). When the oceanic lithosphere cools enough so that its density is greater than that of surrounding rocks, it sinks, again under its own weight, back into the asthenosphere, forming a subduction zone. At that point, especially if subduction occurs on both sides of the spreading ocean, the ocean may begin to contract, eventually closing as a competing ocean opens. This is a Wilson cycle (named for J. Tuzon Wilson). All of this may go beyond what your purpose is in this discussion, but I think it's important to the story as a whole.
Great presentation. I have travelled these ridges and valleys my entire life, motivated by curiosity and just the sheer beauty of the ranges. I love to be able to contextualize their present state with earth history. Thanks very much.
beautiful, one of america's best landscapes... so interesting to take to heart the geological underpinnings of it all...
Thank you, thank you for explaining this and for the pictures. Where can I get more of this fascinating history? I’m a native to this area and studied some geology in my youth - but this is the best I’ve ever seen!
I know this is an older video but it is so well done! Love the connections drawn to the himilayas it really puts things into perspective.
Thank you for a very informative look at various orogenic episodes on the eastern side of the US. At one time, back-in the early to mid 1970s, I was a geology major and maps back then referred to almost the entire eastern region of mountains as the Laurentian Complex. I know the Laurentian chain is strictly in Canada. However, that was the early 70s, and plate tectonics was in its infancy here in the US. I have a signed first edition, 1961, of J. Tuzo Wilson’s book on the IGY. I keep it stored in a hermetically sealed container.
That was more interesting than I expected from the thumbnail. The video needs to be four hours long, though, as one chapter in a series of thirty sessions. 😁
Excellent!!! I live on the Piedmont of North Carolina, and found this most informative.
Thank you for your clarity in your presentation! I'm studying this for a plate tectonics course and this was incredibly helpful!
Very good explanation for collision zone characteristics and denudation process activities, Thank you indeed. It is very usefull for me and all geologists.
Thanks
History is timeless...🤔
Very well explained, I enjoyed it
This was awesome!
Great concise presentation. Thanks.
Excellent presentation. Thanks for sharing.
excellently done! very clear and correct to the best of our knowledge to the present day.
Great presentation, exactly what I was looking for, to help me understand why the Shenandoah River is bendy
Thank you
Fantastic presentation some really neat visuals and a great explanation, I think it was just too fast,... I was having to stop the video frequently because my head was exploding too much. Slow down please. Thank you for the presentation it was really interesting and a great summary of the geologic history of the Appalachians. How many mountains were created by oceans dying!, lol, I thought that was a funny way to think about it! Also who knew the Piedmont region was the basement rock and The core of the heart of the ancient mountains that were closer in size to the Himalayas. Wow.
Great video Callan!
Very cool. Love mountain geology. Would love to a presentation like this about the Adirondacks...
The Grenville orogeny (c.1 bya) at opening of the Iapetus Ocean preceded the Alleghanian orogeny (c.300 mya) during the closing of the Iapetus Ocean. Interesting this battering of the eastern coastal region of the US.
Very informative. Thanks
This was pretty cool! 😎❤
The cake illustration was NEXT LEVEL amazing! I love it! Did you make this illustration yourself?
thanks for video
great video
Thanks, that was great
I love this video, and to think all in less than 10,000 years, just kidding. I used to be a tree planter I noticed just south of Elberton Georgia what look like glaciated Terrain, very flat Granite ledge with scour marks. I wonder when this could have happened? Also errant boulders with strange water erosion at the base right there sitting in water millions of years ago?
Great video. I have lived in north central Pennsylvania most of my life. I have always wondered why the ridges look the way they do.
Thank you.
Thanks for the pep talk. With that east coast oregeny and Australia's east coast oregenic geology (the Macquarrie Arc, I believe) we're practically related.
It would be interesting to forecast\map what the Himalayas could look like 30 - 90 million years from now as well as where on earth the next Himalayas will spring from. Old video but its really holding its own because the care and detail that went into it.
Thank you for the video! The Ouachita mountains are the source of a rock called Novaculite which, among other uses, has been used to make sharpening stones. Can you shed any light on this particular region in terms of the formation and time scales? If I were to research the history of the Appalachian mountains equivalent to finding out about the Ouachita mountains? My interest lies in the fact that I'm a woodworker and use stones mined in Arkansas to sharpen my tools.
First rate video, thank you
very informative
Shout out to the Canadian Shield.
Sorry, I didn't catch a couple of typos in my post. I'm usually not that careless.
I think the shoreline was parallel and along the equator at the time. This made it prime ground for activity during the Carboniferous period, for 60 my before Pangea +/-
You almost totally missed the formation of the back arch basin and the foreland fold belt, although your introduction includes a cross section illustrating these from the Geologic Map of West Virginia!
>^..^< Vary in interesting and informative, thank you. By chance do you have any idea where I can learn about the geology of the USA's rivers? I live near the Delaware river Water Gap area and have always wanted to learn more about my area river's history.
A documentary series called How The Earth was made said concerning the Alps and Rockies that they were as high as the Himalayas in their prime. Is this true of most mountains ranges and plains that use to be mountain ranges? Is there a formula that predicts the future height of mountains based the difference in the ages of the mountain ranges from around the world and the height?
Hey i live right across the street from nova cc
Very good video. How far did the southwest end of the original Appalachians extend? Now they go under the coastal deposits just southwest of Birmingham, Alabama. But it looks like they originally extended much further. Did they go into Gulf? All the way to central or south America? Thanks.
All the way to Australia. But way back then Australia was just west of texas and was part of the scrunch that rose the Appalachians. So it eventually broke off and drifted away to where it is today with its part of the Appalachians still attached. Same rocks do exist on both continents.
@@leebarnes655 I knew they extended all the way to what is now northern UK. Did not know this.
@@HeartlandTuber Moar better video shows Australia coming in from the the current northwest instead. Apparently a scrunch event event from all sides then. And moar Appalachians all around for everybody too.
10/10
Are the figures at 6:10 original figures, or do you have a reference for them? They seem like helpful schematic diagrams.
Hi Edwin, I drew them, but I was definitely inspired by a predecessor image showing the long term denudation of mountain belts... Can't remember where I saw it though; I drew this 15+ years ago now... Maybe a historical geology textbook?
Mr Callan Bentley thanks a lot for this video make me easier to know about collision in Apallachian Orogeny. Can i make this video to my references ? i appreciate a lot this video. Greetings Geologist from Indonesia
Pick up Ron Blakey's books "Ancient landscapes of the Colorado plateau and ancient landscapes of the western North America.
Given its broad application, everyone should understand GEOLOGY - therefore this video has been indexed and a link added by DR-KNOW / iq-2k Information Services - roughly 650 videos have indexed for this series
Great video but those audio glitches are SO annoying....
unlike to the previous comment - if you only knew how hard it is to understand for the one just starting to learn geology! So many confusing details for a novice!
::)
What is the evidence of plate subduction?
When I see the cross section of the subduction zones, also known as trenches, they are symmetric, deep, it's looks nothing like a place two massive rock plates are colliding and sliding into the earth.
How can oceanic crust even suck into the mantel and not make bulge above?
Anyway, what is the DIRECT EVIDENCE of plate being subducted into the earth's mantel?
They do make a bulge! That's one of the strongest pieces of evidence for subduction.
@@callanbentley Where is such bulge located?
Can you give me an example?
@@sbkarajan
The islands of Japan
@@roypatton1707 Japan is not a bulge due to continental plates sliding and rubbing each other, it’s more like Hawaii and Caribbean islands or part of Italy, etc, just a mass of rock made of volcanism.
If continents are sliding and one of the is magically subducting, there should be some sort of bending and grinding going on.
I don’t think there is any evidence that subduction is happening, it’s just a pure assumption, guess, or more like a claim that’s unprovable.
@@callanbentley What should bother you is that around Antarctica, there are mid ocean ridges where land is created, but there is no subduction around it.
Apple-at-cha
what is its significance with evolution
Ap-a-latch-uh..........not Ap-uh-layshua. Just for the record.
Tom-AY-to, Ta-MAH-to.
Callan Bentley that’s how we know “ y’all ain’t from around here “. Lol
@@callanbentley Not necessarily
Usually, if nothing else, it's polite to pronounce areas and things as the people from there would, if you can
It doesn't take much effort
The peoples from that area, especially, are people science needs to reach out to
Not snub them and further their anti intellectualism
I've lived most of my life in the valley and ridge of Pennsylvania, and we say App-a LAY chia. So there. 😅
@tipperpressley
great video