The Ultimate Guide to Sedimentary Structures- Sed Strat #6 | GEO GIRL

Learn about sedimentary structures, such as laminations, cross bedding (planar vs trough cross bedding, herringbone cross stratification, & hummocky and swaley cross stratification), ripples, graded bedding, growth bedding, and mud cracks!
In this video, we start with defining beds, strata, and laminations, and the geometry of bedding. Then we discuss planar laminations, such as varves or tidal rhythmites and the depositional environments where laminations form (calm waters such as lower shorface, pelagic marine, glacial lakes or glaciomarine, or low energy tidal environments). Then we move on to planar and trough cross stratification & the depositional environments where cross bedding is common, such as eolian (desert), middle to upper shoreface (or lower shoreface during storms), high energy tidal, and fluvial (river) environments. Then we discus hummocky and swaley cross bedding and then herringbone cross bedding. Since cross bedding is the result of dune or ripple migration, we also go over the difference between dunes and ripples (which is just scale). However, ripples can also appear on the tops of bottoms of preserved beds in which they can further narrow the possible depositional environment. There are symmetrical and asymmetrical ripples. Asymmetrical ripples form due to unidirectional flow, such as a river, and symmetrical ripples form in bidirectional flow regimes, like some tidal systems or mid-upper shoreface environments because waves are symmetrical orbitals that only become directional when their base hits the sediment near the beach/foreshore. Then we touch on climbing ripples which indicate waning flow such as upper sections of turbidite sequences (Bouma sequences) or when fluvial environments flood and flow velocity decreases and deposition occurs. Then we go over heterolithic bedding like flaser, wavy, and lenticular bedding and how it may form in tidal, fluvial, or glacial environments. More mud (lenticular bedding) indicates calmer waters (low energy systems). Graded bedding is typical of the base of Bouma sequences caused by turbidity currents. Growth bedding is typically of chemical precipitation (chemical sedimentary rocks) such as evaporites. And lastly, mud cracks form due to dessication of mud in dry environments.
References: Sedimentary Rocks by Pettijohn: amzn.to/3tnWuVu
Sedimentology and Stratigraphy by Boggs: amzn.to/31VIG9x
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!)
0:00 beds vs. strata vs. laminations
2:12 bedding geometry & lateral continuity
3:36 planar lamination depositional environments
5:45 seasonal laminations (varves)
6:55 tidal rhythmite laminations
7:43 lamination preservation requires low O2
8:44 planar vs. trough cross bedding
11:05 hummocky & swaley cross bedding
12:17 herringbone cross bedding
14:44 dunes vs. ripples
16:12 symmetrical vs. asymmetrical ripples
18:01 climbing ripples
20:09 flaser vs. wavy vs. lenticular bedding
21:51 graded bedding & turbidites
25:29 growth bedding
26:55 mud cracks
28:17 related videos & references
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[@GEOGIRL]

Hi everyone! I really hope you enjoy this video! It is actually one of my all time favorites because I feel as though I would've loved to have a guide like this when I was taking sed/strat (not to toot my own horn or anything haha)! It's the kind of video you can come back to for a refresher if you need it. And I know many of you are not students and don't need to know about sedimentary structures and their depositional environments, but I hope you enjoy it anyway lol! I mean even if you aren't a student, it is fun to go for a hike and know that the rock you're walking on used to be in a beach environment ;) P.S. sorry not sorry for the cheesy intro lol😅

[@GEOGIRL]

@mohammed ghazi You're so welcome, I am glad you liked it ;D

[@nayemhossain9796]

F

[@younesmegutif5815]

Can you send some exercice pliz

[@ggeduction7087]

you are such an amazing geologies. thanks for videos you shared

[@ggeduction7087]

I have a question plz. How could I know the depositional environment from the core facies ? any hints

[@paulsufi1082]

I appreciate so much your videos. It's helping me a lot, to understand all this mess!!!

[@space0077]

It's an honest confession , I just love your smile and how your left eyebrow moves every time in the beginning. Btw great content as always 👍 I have learnt a lot from your videos. Thank you very much.

[@GEOGIRL]

OMG! I just watched the beginning back because I never noticed that I do that with my eyebrow!!! LOL I sort of hate it! hahaha But I love your comment, you are too kind, thank you

[@snowg103]

Thank you so much for this video! I'm in Sed Strat right now and this video (and all of them pretty much lol) are so helpful!

[@GEOGIRL]

Wow, thank you so much for this comment, it made my day! I am glad you found this and other videos of mine helpful! If you ever want to suggest a topic for a future video, just let me know ;)

[@chrisconnors7418]

Wow! I didn’t know 90-95% of that. Very informative. Now I’ll have to see if I can track down one of those textbooks. Next time I visit Utah area I want to be able to look at the layers to understand what I’m seeing.

[@dallasryle7740]

bed shapes can be, tablet, wedge, trough, lunate trough, lenticular, lens and cylinder, ...transport currents which form these sedimentary features can be fluid gravity currents or sediment gravity currents ( i. e, turbidity currents, Bouma and Lowe's sequencing are helpful to analyze graded bedding e,g, in vertical sections, post depositional structures, flute features, casts, groove casts, grazing impact casts, soft sediment deformation and later determining paleoslope direction, and bioturbation and trace fossils..( all from compton's field geology)

[@peterjodway2543]

Awesome stuff. Huge fan of the 'Ultimate Guide' format! esp. big appreciation for the lamination and alluvial datazzzz :) Honestly, the mud is the HEAT, GeGi!!! I'm still being gravitated toward the effects of post-Wurmian mudslides and how they contributed to differences in alpine zones throughout geological timelines... I'm obsessed with the first traces of human civilization in the same way you are obsessed in the first traces of carbonaceous life :) The mudslides and alpine zones that were happening in the Caucasus, Taurus, Zagros and Andes ranges during the retreat of the last glaciation are what especially interest me as they are the ones that seem to have the most attention given to them (in Western lit, anyway). I often wonder: why is Africa so obscured in its geological data? I understand that there are political difficulties, but... We seem to have no issues as Westerners investing in 'artisanal mines' that produce hand-picked diamonds out of mud caves that only the most 'expert artisans' (those prepubescent African children who are just the most nimble and quick dirt-scratchers) can even fit into... why is it so hard to achieve geological surveys of the continent that would seem to only benefit the industrial complex/local economies? Do we get the same info from our South American research, as the two kratons [sic] used to be connected? I'm a self-taught sous chef who regrets his career choice (hahaha), so the reference materials you provide at the end of videos is a blessing; I've been stuck with an old 90s edition of the Cambridge Histories to research out of, supplemented by Wikipedia and recently - thankfully! - your videos. Please forgive any outdated language I'm using. Thank you much! on that note.... why has no one made the official term for 'geological language' "GEOLE"? (sounds like 'creole'?) They are both equally impossible to understand and they are both amalgamated languages that evolve monthly. and it is just one more term for geologists seeking to bring shorthand to spoken language, no? Geole > geological jargon > longform scientific classification structures... it's on you now, GG. Make it happen! 😆😂

[@GEOGIRL]

Oh my gosh, I love this comment! And I love the idea of GEOLE hahaha Thanks so much for the kind words and encrouagement, I really appreaciate your support ;)

[@canadiangemstones7636]

Awesome content, much appreciated!

[@stevenbaumann8692]

This is the first time you’ve appeared on my feed in a long while. I see you’re doing well. Also well done on this episode! I’m glad you have a great interest in geology.

[@GEOGIRL]

Thanks Steven! I am glad this video showed up for you and I am glad you liked it ;) I see your videos on my feed often, and I love them! I really appreciate what you do as well :)

[@user-nc3qy2md2v]

thank you very much for your introduction about sedimentary sturctures -- i need introduction about sole marks ---You are a great teacher

[@GEOGIRL]

Thank you so much! :) I actually have a video about bedding plane markings, that you may find helpful: kzbin.info/www/bejne/aKWrhWd_otCcl68

[@lonewolf4343]

Kudos ! Great quality content. Explained simply.

[@GEOGIRL]

Thanks so much! ;)

[@Get_to_the_Point]

I learned a lot from this. You are a great teacher !

[@GEOGIRL]

Thank you! So glad you found it informative ;D

[@Smilo-the-Sabertooth]

Another interesting video. Thanks for helping me spend these last twenty-nine minutes wisely. I can’t think of a better use of my time than to learn and increase my knowledge with some one as beautifully gifted and intelligent as you. Always such a tremendous pleasure for me. My full support for this amazing channel is still going strong. And by the way, I really love your sweater. 😊❤😉👍

[@GEOGIRL]

Yes! I was hoping someone would notice the dino sweater 😂 Thanks for the comment, you give me too much credit as always, but I love it haha💛

[@Smilo-the-Sabertooth]

@@GEOGIRL Yeah you’re welcome Rachel. ❤👍 Dinosaurs never go unnoticed by me. 😂 And I’ll give you all the credit because you deserve it. You’re amazing my beautiful friend. 😊❤😉

[@fimethr6248]

saving my life JUST before my paleoenvironmental geology exam

[@GEOGIRL]

So glad this video could help, best of luck! :D

[@fpgt91]

Great introduction to sedimentary bedforms. Some exceptions: Megaripples - such as those observed in the scablands of Washington state and other locations were mega floods have occurred. There are also marine megaripples caused by currents and interference. I believe Mars also has some megaripples.

[@laflame5662]

Helped me achieve my grade e, thank you

[@XinLi-xs3kk]

Thank you so much for your amazing vedios! So Cool!!

[@threedot141]

I have just an amateur interest in geology but your great videos have helped me to understand much of what I read and see on other channels. Thanks! Your diagrams and explanations are really clear.

[@GEOGIRL]

Thanks so much! So glad you have found my videos helpful and interesting :D

[@MrK-tb9qi]

I love your explanations

[@GEOGIRL]

Thank you! :)

[@yayamal1]

professional presentation

[@ellenmcgowen]

Someday please do a video about sedimentary structures on Mars. I think Mars has known examples of most sedimentary features: rivers, deltas, lakes, aeolian dunes, blind canyons, dendritic pluvial features, catastrophic outflows.... everything except (so far) BIFs.

[@GEOGIRL]

What a GREAT idea, thanks! :D

[@jirumedia]

very nice presentation

[@DidZed]

Hello GEO GIRL, Very interesting video. I discovered your channel through my research. I play geocaching and more particularly its geological part. I live in an area of Brittany where there are a lot of geological curiosities that I would like to make discover from the game. I am always looking for information and especially in English. So I can make descriptions in this language and I can learn more about it at the same time. So thank you for all the work and your availability. I really appreciate it. And when I see all the videos you've made, it's incredible and all with a surprising ease. Well done! 👍😀

[@GEOGIRL]

Wow, thank you so much for the thoughtful comment! I assure you it was not with ease, but I am glad it looks that way ;D haha Your research sounds very cool! Best of luck ;)

[@REAAX]

This is ridiculously hard!

[@GEOGIRL]

Well I hope the video made it at least a little easier ;)

[@OrchestrationOnline]

"By Jove, Holmes, what sort of rocks are THESE?!?" "Sedimentary, my dear Watson, sedimentary..."

[@mayankjuyal6300]

Good content

[@GEOGIRL]

Thank you, glad you like it! :)

[@sciencecafe1543]

Great video! I taught all of this stuff for one of my TA ships and you have covered most of the basics on this topic! Another great video! Are you going to do an inchnofacies video in the future? On another note, I emailed you the astrobiology workshop. Hopefully it's useful to you! Please don't hesitate to ask if you have any questions.

[@GEOGIRL]

Yes, I got the email, thank you so so much! And I have some videos on my channel where I discuss ichnofacies in the context of other topics, but I never thought to make a whole video on it, what a great idea, I will now haha, thanks! ;)

[@nickfosterxx]

15:40 Er, giant ripple forms from eg Missoula flood -type events? BTW, thanks so much for what you do, been searching for a channel like yours for years, in for the long ride. The barrier to entry always seemed high until now. A couple of books on Scotland got me started when I first went there to that compelling NW landscape.

[@user-nb7fz9kn2o]

Correction @9:19 grains move from the stoss towards lee of ripples and dunes.

[@JoesFirewoodVideos]

Please educate me doctor 👩‍⚕️ I ❤️ GEO GIRL

[@ukaszbadura5670]

I think I found ripples in the “forbidden zone” and heterolithic bedding in a tuff rock.

[@mohamedashrafelsherif6458]

amazing

[@GEOGIRL]

Thank you! :D

[@DB-kq8kp]

Excellent video, thank you from a Petroleum Engineer (who tries to keep up with the Geo's). Question : Are planar laminations also possible on low angle near shore face(s) where the water depth is very shallow and the velocity of the water scours the sand flat removing any ripple structures ?

[@ukaszbadura5670]

I am looking for literature or articles which talk about depositional environment which can occur in vulcanite tuff. I came across tuff which has clear cross bedding and stratification and very interesting geometry of these features.

[@user-nb5sh4bl7h]

Look at Rocks the same again Video The Mud Fossil channel Process creates perfectly preserved parts of ancient creatures

[@aymenadil84]

Thanx, It is a fantastic presentation. I wonder if I can get a copy of your presentation in PPT format?

[@daviddimovski9595]

This is all well and good but, what are your thoughts about the shynx and the errosion of the enslosure wall lol. Water or wind?

[@kierenyu8974]

Hello, I am sorry to bother you, but I would greatly appreciate your help on this question. I am confused about the definition of cross bedding. I observed some wavy bedding on rock cores. During the heterolithic bedding interval, the sands are very uniform, but the mud strata can be found truncated by other mud strata, looks a bit like sws. In this situation, can I call it swaly cross strata?

[@princeshukla7661]

My first comment

[@GEOGIRL]

You beat me to my own video haha ;)

[@princeshukla7661]

@@GEOGIRL 😂😂😆

[@ramchauhan5238]

You and your voice is so beautiful ..🙃🙃👌

[@GEOGIRL]

Thank you ;)

[@ramchauhan5238]

@@GEOGIRL I want to ask you one question... Mam,. Who is your favorite Indian cricketer ?🙃

[@ramchauhan5238]

@@GEOGIRL most welcome mam..

[@GEOGIRL]

@@ramchauhan5238 Haha, I don't watch cricket, unfortunately. Who is yours? ;)

[@ramchauhan5238]

@@GEOGIRL m.s. dhoni and virat Kohli...🙃😊

[@mariarugaard4870]

Hi Geogirl :) It's a great video - thank you for doing such a superb job :) btw, what is the sed-strata book you use? Thanks again.

[@GEOGIRL]

Thanks! I use both of these: Sedimentary Rocks by Pettijohn: amzn.to/3tnWuVu Sedimentology and Stratigraphy by Boggs: amzn.to/31VIG9x But I find the second one (Boggs) a bit of an easier read and with more pictures haha ;)

[@ryanw1433]

Question on the drop stone picture - I can see how the drop stone would deform the laminations under it, but why are the laminations above the stone distorted so much? Wouldn’t they deposit in a neater looking drape over the stone?

[@GEOGIRL]

Yep, absolutely, they just drape over the stone, so you typically get a slight curve of the layers above the stone and they also are often thinner on the slopes of the stone as sediment slides down the edges if it is a round stone. The picture looks more deformed only because of later (post-depositional) weathering & erosion. When those layers deposited, they would've looked like a very smooth curve over the stone. :)

[@joeyhinds6216]

That is fascinating about the forbidden wavelengths. I've heard this before I think, has it something to do with the grain size of particles? And would there be this kind of size exclusion found in a similar marine environment or do dunes even form underwater??

[@GEOGIRL]

I actually only stumbled upon this concept while researching for this video haha, but to my understanding it applies to all circumstances, aquatic ripples & dunes and wind ripples & dunes.

[@AbhishekKumar-ry9ls]

I love your videos. Great work Can you please explain festoon cross bedding ? If u have already made a video please share the link 😅

[@GEOGIRL]

I don't have a video with info on festoon cross bedding yet, but I will put it on the list of future sed strat videos! ;)

[@AbhishekKumar-ry9ls]

@@GEOGIRL sure 😊

[@kierenyu8974]

Great video 👍 thank you a lot! I still have a question. What is the depositional environment of fine-medium grained sandstones with planar beddings?

[@GEOGIRL]

It could be shallow (upper) shorface, tidal flats, or river (fluvial) flood plain depending on whether it has interbedded mudstone. If there is no or limited interbedded mud, it is probably upper shoreface or beach, and if there is interbedded mud, it is probably tidal or floodplain. :)

[@kierenyu8974]

@@GEOGIRL thank you 😊 you’re a good teacher

[@user-qq3xs9hb5w]

❤

[@user-bz9um8vl6p]

Hlo mam, with due respect I want to ask that how in turbidite sequence we are getting high energy mud and sand which is different from plannar cross bedding concept, can you please explain it more?

[@samakshgupta8750]

Please make a video on different metamorphic textures and phase diagram in metamorphic petrology 🙏

[@GEOGIRL]

Will do ;)

[@samakshgupta8750]

@@GEOGIRL thanks🙏

[@trobertw]

Don't get all sedimental on us

[@GEOGIRL]

🤣no promises

[@brucejackson3940]

Spicy

[@ashutoshjadhav7224]

hi geo girl, m lil confused on whether to say that ripples dunes and and anti dunes dont follow law of horrizontality

[@GEOGIRL]

Hi there, sorry if I misspoke, but ripples and dunes do still folllow the principlie of original horizontality as well as the other stratigraphic principles :)

[@ashutoshjadhav7224]

@@GEOGIRL thanks. 🙂.

[@princeshukla7661]

Today u looking so beautiful thank you so much Love from INDIA

[@GEOGIRL]

Thank you so much, you are giving me so much confidence! hahaha😂

[@princeshukla7661]

@@GEOGIRL always

[@ericsimpson8218]

Don't forget my megaripples :)

[@chrismullin9437]

I'm enjoying your sed strat playlist, but I can't quite believe that sedimentation can happen so quickly. At 14:00, you have an example of flood& ebb crossbedding. The flood bed thickness appears to be 0.5 meters thick, per the sale on the side. Was 50 cm of sediment (after lithification, no less) deposited in just 6 hours?? Sounds impossible.

[@jackhawez10]

Sure, most depostion occurs on a very long timescale, but I think you would be very suprised on how much depostion can occur in a short period of time given the right conditions. There are many examples of this geologically.

[@velikerimov9703]

GeoGirl glayy minerals pleaseeeeeee

[@GEOGIRL]

Haha, I know, I have that on my list ;)

[@velikerimov9703]

@@GEOGIRL why?😃😃

[@GEOGIRL]

@@velikerimov9703 What do you mean why? Because you said you wanted it haha

[@velikerimov9703]

@@GEOGIRL I misunderstood sorry GeoGirl🙂thak youu

[@GEOGIRL]

@@velikerimov9703 No problem ;)

[@AbdurRahim-mm9pi]

No offense but be a little bit serious while explaining a topic

[@GEOGIRL]

My whole thing is I hate that topics in academia are always explained in a way that is so serious and (in my experience) quite boring, so I try to be fun and sometimes silly I guess, but I like that about my videos because that's what I learn best from. However, I completely understand if that is not your preferred style, I am sorry about that! We all learn differently :)

[@canadiangemstones7636]

My dude prefers the serious style of his professors at Trump University.

[@jirumedia]

for further information i need your contact