Geologic Time & Dating Rocks Without Isotopes (Biostratigraphy & Lithostratigraphy) | GEO GIRL
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- เผยแพร่เมื่อ 13 ก.ค. 2024
- In this video, we go over how the geologic timescale was originally built. The modern geologic time scale has numerical ages associated with each time period, but originally we used fossils to construct the timescale. The use of fossils to date and correlate rocks globally is called biostratigraphy. Biostratigraphy is still very relevent today because we cannot use radiometric dating on all rock types. For most sedimentary rocks, we have to use their fossil content to figure out their age. I talk about the general principles behind relative dating of rocks (dating rocks relative to one another rather than using radiometric techniques) and how biostratigraphy works, specifically the use and characteristics of index fossils, in this video. We then go over how we can correlate rocks using other metrics, like rock type (lithology) and magnetic signature. The use of lithology to correlate rocks is called lithostratigraphy, and the use of magnetic signature to correlate rocks is called magnetostratigraphy. We can now go over and check out stratigraphic correlations and ages using radiometric ages of the rocks to correlate them and make sure it matches what we determined without radiometric dating. This use of rock ages for correlation is called chronostratigraphy. All of these stratigraphic techniques help us piece together everything that has happened through earth's history and when it all happened. I give an example at the end of the video of how we can use stratigraphy to find periods of sea level rise and fall in the rock record (trangsessive and regressive sequences). Hope you enjoy! ;)
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0:00 Video Outline
0:57 Geologic Timescale Overview
2:54 True Scale of Geologic Time
3:39 Absolute vs Relative Dating
4:53 Relative Dating Principles
7:54 Ordering Geologic Events (Practice)
10:35 How The Geologic Time Scale was Made
12:07 Extinction Events Define Period Boundaries
14:11 Stratigraphy & Correlation
15:19 Index Fossils for Biostratigraphy
17:40 Index Fossil Examples
19:24 Is Biostratigraphy Still Used?
21:16 Magnetostratigraphy
22:53 Lithostratigraphy
23:31 Strat Columns & Cross Sections
25:08 Transgressive & Regressive Sequences
26:47 Unconformities
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What about ordering the unconformity itself, not just the layers above and below it?
Yes that is very important as well! I should've done that with the example, thanks for pointing that out!! I'm going to pin this comment so people will see it and know that they need to order the unconformities too :)
@@GEOGIRL I thought you did mention ordering unconformities as a way we can see water levels rise and fall giving us evidence of climate conditions?
@@leechild4655 I did mention unconformities at the end, but should've also mentioned how we can order them in the ordering geologic events practice part earlier in the video :)
The Cretaceous derived from the Latin word Creta (Chalk) The (K) in the KT boundary layer is an abbreviation for the German word Kreide (chalk)
Neat! I thought they used the K to differentiate it from the Cambrian in appreviated charts like the one used for organisms at the top right corner of wiki. Could that be why they German word for chalk? because Cambrian and the KT are well known important boundaries
KT is German for
Kreide-Tertiär.
Kreide is German for chalk but means here Cretaceous.
The C is already used for the Carboniferous.
Oh cool, thanks for the info! :D
@@GEOGIRL Yes
Ok, I was too slow on this one :D
I still call it the KT boundary.
@@nicholasmaude6906 Haha I do too sometimes 🤫
Thanks for the levity and knowledge, i needed a bit of that to get my mind of things !
Enjoyment on a geologic scale! Always great to see another Geo Girl clip.
Great video Geo Girl!
Thanks! Glad you enjoyed it :)
That diagram at 8:00 really was a flashback to my college days! We really had those drilled into heads - ordering rock layers in vertical cross-section AND in horizontal aerial views. (Those aerial view diagrams can be trickier!) Then a few years later, I had to practice them again for the ASBOG exam. They’ll always be around!
Because of one of my Profs, I don't need no steenkin' song to remember parts of the Cenozoic....Half a Century later, I still remember PEOMP.
😂
That takes me back college in the early 1980s. Thanks☺
Really appreciated the slide on how using absolute dating and magnetic stratigraphy allows tracking the movement of the magnetic poles. Missed that in the ESH text.
Great discovering of this channel today in my you-tube! As a Math teacher I love to bring in some Earth Science in Algebra, makes Algebra more 'science-y' on this Earth. Lol. Thanks!
Wow! It's so cool that you can incorporate Earth science into math! I never would've thought of that, how innovative! Keep it up ;D
Thank you! This is something I'll be looking for every time I see rocks now!
THANK YOU! I knew a bit of this, I am a rank amateur, but you have filled in so much for me. I know that it is just an overview but this is almost half a term of a class on this subject. Good Midterm exam material!
I need to keep a link to this vid at my elbow so that I can send it as a reference to so many science deniers. They may not look at it anyway, their loss, but you have explained things so very well.
Keep up the good work! Hopefully you inspire some budding Geologists, Paleontologists... Earth Science enthusiasts!
Thank you so much for the kind words and encouragement! I hope I inspire some future geoscientists as well! :D
Excellent work...wonderful voice ....a gift for clarity ... what you do is so positive !
Thanks so much for putting these presentations online, free for all ❤️
I'm not a geologist, but I'm so glad I can learn about geology from stuff like this. ☺️
KT-boundarywith a "K" - my guess, because of "Kreidezeit", the German word for the "Cretaceous".
Very thourough explanations! I wish i had this course when i was in high school, i would have understood the Landscape around me wayy better! First time ive ever taught about Lithostratigraphy by the sea! Omg, so much insight!! Knowledge is Power! Damn! You Powerful, girl! ;P
STRATEGERY
This is a really good overview. 😃👍
Yay! I've been waiting for this one :) Nice job!
Thank you! :)
Wonderfully done!
I just gotta say, your videos are absolutely amazing. I feel like I'm in a legit GEO101 lecture and I'm loving it
actully its great effort in small time your explanition is really great
You should do geology overview by state! Would give you 50 videos, and people are biased, they want to see their state in your videos.. Start with Michigan though, lol.. ❤ LOVE your videos! Thank you so much!!!
Channels like yours is much needed on this platform. There's too many psuedo scientific channels crowding around. I hope you will hang on here for as long as possible. Thanks for your hard work uploading...
I absolutely love your work here.
Thank you so much
The era I've looked into the least, haha. Thanks for making this.
I watch your videos every day.
They are so chocked full of free and well compiled knowledge, I feel like I could go into geology and even paleontology as a profession by just watching your vids alone! (Alas I still think I would need an actual scholastic process to do any serious research haha, or at least any research taken seriously by academics. But still I'm self teaching and hoping one day I can surmount that barrier.
Amongst a sea of woe, thank you for helping to keep the internet a great place to learn!
Also: I secretly wish one day you would branch out into astrophysics and tackle the domain of the cosmos and quasars and black holes and such, but keep doing what you're doing since you care for it so mucj!
Rachel: In the “Ordering Geologic Events” graphic shouldn’t the angular unconformity event be designated #7 and the green layer be considered #8? The top unconformity event would then become #13.
Yes absolutely! I already got a comment about that earlier and pinned it at the top so others know that they should order the unconformities too! Thanks for catching this ;)
Loved it thank you! I actually learnt some stuffs.
Geo Girl ROCKS!
Super informative video, thanks!
Of course! Glad you found it informative :D
everything is layer by layer! thank you Geogirl
I'm preparing some introductory lessons about geology and I stumbled upon your videos... They're great!! You're helping me a lot, definitively gonna recommend you to my students
Thanks so much! I am so glad you've found them helpful, I hope your students do as well! :D
That video really was a useful one!
Older than me, and I'm not young anymore. All praise Old Granma Gaia, the matter and the potential*!
*That's actually how Gaia reads in Basque.
"Relative dating" is what the Habsburgs were really into.
Yeah, they were serious about keeping it in the family.
@@nicholasmaude6906 The Aristocrats!
I love you and your work..
great review of basic geology timescales! thanks
What about "geological windows" (translating here from German, I don't know if this is the term in English as well), when older layers or "beds?" overlay younger strucures, is this an "unconformity"?
(being a fan of "geological windows", because here in the Alps, this is where we can find the most interesting minerals).
Incredibly talented ❤
Steno’s laws are burned into my head… 😳
haha, yea geology courses will do that :)
Honestly the easiest way to remember the time scale is figuring out what the words actually mean.
Often it's like. Old life, middle life, abundant life, new life. Not too crazy. And other times people name them after places that have a lot of fossils in that area right at the surface.
That's a great point! The ones that have the term paleo, meso, neo, etc. are pretty straight forward haha :)
You might want to note in future videos that outside of the U.S. the "Mississippian" is the "Lower Carboniferous" and the "Pennsylvanian" the Upper.
Oh yea thanks for the reminder! I keep forgetting that's a US only thing. Will do! ;)
@@GEOGIRL No problem :) I keep looking out for your cat :P
Legit thought this was about how rocks reproduce until I realized which "dating" you meant.
Thanks geo girl
You are very welcome! :)
I thought relative dating was frowned upon in most societies. ;-)
Another excellent video, BTW.
It is especially if it's siblings😉😁.
Guess who is going to a road cut out to try and date some rocks! Though I am pretty sure we just have Mesozoic limestone here in San Antonio. The cool thing about my house is it sits at multiple types of rock intersecting according to USGS.
Yes! That is awesome!! :D
Ah-mazing video!!! This is really helpful for studying for the asbog exam. At what point would the holocene end and how do we decide the ending of time frames going forward?
As an Australian, I must point out that the term "relative dating" has a whole different meany in Tasmania . . . and New Zealand. That's gotta be an oldie, but still a goodie, right?
Igneous intrusions can be dated absolutely using radiometric dating.
Yep! Igneous rocks are perfect for radiometric dating :)
I have an Ammonite! About a 6 inch diameter. Could’ve got a 30+ pounder but it was over 30 pounds lol. Also got a couple of other fossils from a Geo thing at a mall in San Antonio. That was fun.
"Dating rocks" - who's your date tonight? I'm going to date a rock.
Great video on geologic time & dating rocks Geo Girl! You included 3 "unconformities" but isn't there actually 4? My Geo text book mentioned "" -usually a long period(Ma years) of "non-deposition between parallel layers". Your explanations help me better understand the material, thanks!
Great question! So, in the case of a long period of non-deposition, that is a type of nonconformity, so it still falls under those three major types :) Hope that helps!
@@GEOGIRL Sorry, my post didn't include the term paraconformity that defines "non-deposition between parallel layers." They mentioned this as the 4th type. -Thanks ☺
well done
Ok this is epic
Geology is so cool
Couldn't agree more!
Relative dating, isn't that illegal? (I'll see myself out)
I was in a small town in Alabama the other week, they were really into relative dating, weird because they didn't seem to know anything about geology.
The criteria for good index fossils seems to be very stringent. Obviously it needs to be for accuracy but does that leave very few fossils that fit or are there hundreds or thousands of good examples? If a fossil lacks of the criteria mentioned, would that be used to narrow down the age of the rocks just with less confidence? Or is there almost always a good useable fossil?
Edit: Never mind you pretty much answered my question, maybe next time I will watch the whole vid before commenting.
Do you get much push back from "Texan Krischins"?
You and Forrest Valkai should do a joint video on some topic.
OMG, u sad, that u live in El Paso?
I was stationed for 5 years at Holloman AFB wit the German Air Force. That was 2004 - 2009.
Say hello to White Sands, Sun Spot, Cloudcroft and El Paso for sure :)
No to Orogrande... Orogrande sucks :D
Nice video, as always and greetings from Germany :)
Oh no haha I love Orogrande! Lol! But yes, White sands, cloudcoft, sun spot, those are all great as well! :) That is so cool! I have been coming here my whole life, I didn't grow up here but my dad's side of the family is from El Paso, and we still have family in the area so I was visiting long before I moved here for school :) It's one of my favorite places for sure!
I always thought "relative dating" was a breeding process for European monarchies. We live and we learn.
Hope is inert....
Why is the ground around Oilton, Texas two different colors? The east side is purplish brown but the West side is just light brown? When did that happen and what caused the east side's color, hyalobacteria? It seems to come from the coast.
K for Cretaceous comes from the German spelling, Kretazeisch.
No isotopes on Tinder, yet dating there does not rock. Hmmm
Rocks used to date?😮
Would you mind show me the steps of absolute dating with radioactive elements?
"Relative dating"?, I suspect there's a lot of that going on in places such as Kentucky, Arkansas, Alabama and Georgia if you know what I mean😉😁🤣. Oh, yeah, the Ancient Egyptian royal were very serious about their "Relative dating"😉😁.
😎
We aren't in the Holocene anymore we're in the Anthropocene now.
Oh is it officially an epoch now? Or is it still just an unformal epoch name for the current time?
@@GEOGIRL I don't know if it has been made official however I understand that the term is being used increasingly.
@@GEOGIRL I just checked the wikipedia article on the Anthropocene ( en.wikipedia.org/wiki/Anthropocene ) and this is what it says:
"As of April 2022, neither the International Commission on Stratigraphy (ICS) nor the International Union of Geological Sciences (IUGS) has officially approved the term as a recognised subdivision of geologic time,[9][10] although the Anthropocene Working Group (AWG) of the Subcommission on Quaternary Stratigraphy (SQS) of the ICS voted in April 2016 to proceed towards a formal golden spike (GSSP) proposal to define the Anthropocene epoch in the geologic time scale (GTS) and presented the recommendation to the International Geological Congress in August 2016.[11] In May 2019, the AWG voted in favour of submitting a formal proposal to the ICS by 2021,[12] locating potential stratigraphic markers to the mid-twentieth century of the common era.[13][12][14] This time period coincides with the start of the Great Acceleration, a post-WWII time period during which socioeconomic and Earth system trends increase at a dramatic rate,[15] and the Atomic Age."
So, not officially yet an epoch but this could change soon but may instead be officially classified as an event in the end.
@@nicholasmaude6906 Oh cool! Thanks for the info! :)
@@GEOGIRL Given how humanity has been actively modifying Earth's geology in the few hundred years (Things such as the Suez and Panama canals along mining away whole mountains for iron and coal for example) I think that it should be now referred to as the Anthropocene epoch. Perhaps you could do a video about this particular topic, Rachael, about whether or not we should be talking about and Anthropocene epoch and more impurely when exactly did the Anthropocene start.
Damn I'm so early you'll find me at the bottom of a sedimentary formation
Hahaha I absolutely love this comment, well done ;)
Just count the rings, like with trees
You're just over complicating things
Are u Adrienne Thacker????
How old is Eternity-now?, ..one infinite continuous connection concept of Black Hole axial-tangential prime-cofactor reciprocation-recirculation relative-timing condensation visualized as Condensed Matter in terms of elemental e-Pi-i sync-duration Polar-Cartesian symbology. So it should be less of a surprise now, that the existence of temporal strata elemental half lives set in geology, in geography, in star systems etc out to infinite reciprocation-recirculation relative-timing = Spacetime Relativity. (?)
Also known as here-now-forever locally.
This particular lesson is of central importance to knowing who, what, how and why inside-outside holographic positioning presence is Actuality.
Ewww. Biostratigraphy. My Proterozoic rocks don't have those gross macro fossils LOL.
I greatly appreciate you not using the Precambrian and a formal term.
The GSA abandoned tertiary in 2012 and for some reason brought it back in 2018. The international one abandoned it all together. Cretaceous uses K, because of the root. Why? Others don't do that. Honestly it was done because C was already used. Cambrian is a C with a line thru it because , once again, Cwas already taken.
Huh that is so interesting about the tertiary haha Thanks for the info! ;)
Why are the Pennsylvanian and Mississipian not epochs?
Here's a link to Ben G. Thomas's video about why the Great Dying was so bad and I think you'll like it - th-cam.com/video/V62l2wzpuAQ/w-d-xo.html
You are too cute
haha Thanks ;)
I need a shirt labeling myself as an igneous dyke :p (random thought)
Are there any corny pick-up lines, like: I'd like to measure the decay in your carbon 14?
Great video GEO girl. I wonder what you make of this th-cam.com/video/n2ANUKSF2BE/w-d-xo.html. Personally, I find it makes much more sense. It answers many of the questions left unasked by the conventional understanding.
Bye hahah.Good
The best period by far is the nalgene. Especially when you're thirsty.
Why i am getting attracted to you , this shouldnt be , i respect you , from India, your way to explain basics and presentaion is vgood, from now i will not watch any video , so sorry madam ji, otherwise i will come flying and meet u in germany🎉🎉
Omg marry me
Why does geology always use hard words?
You keep talking about dating and members... I'm getting the wrong idea here😅
You really should stop dating rocks and find yourself a nice boyfriend, preferably a doctor. Just kidding.
Are you married?
Dating rocks is complicated. There is zero communication.
This made me laugh out loud haha! :D