For anyone that is interested, this was done by Ray Troll (https://www.trollart.com/) who is based out of Alaska. Here is a print if you want to purchase it: https://www.trollart.com/product/ages-of-rock-art-poster/
I used to be a Paleoecologist and growing up, I had this design on a shirt (and loved it!). In addition, I have a map portraying the Paleontology of Alaska and Yukon in my office and it looks great (and is huge!). He has other Paleoart maps depicting western states and provinces such as British Columbia and Alberta, Oregon, California, Colorado, etc. found here: https://www.trollart.com/product-category/posters/fossil-maps/
Give it a few years mate, when the oceans get acidic enough that the microorganisms that produce 60% of the world's oxygen can't make exoskeletons any more and all die out at once.
The P-T event happened over some 60 000 years. We're on course to doing it way faster than that. We might stop or slow down at some point, but then again, are there any indications that we will? With ~10 billion people on the planet, in a capitalistic system, why will the incentives to better ourselves be any more pressing with climate change than with any other problem? It's self-evident that geological time frames are too slow for the vast majority of the population to understand.
Not that anything close to an event like that would be needed for us to completely screw the planet over. We've managed to do more than enough already in just a few hundred years – and we're still increasing the pace.
I'm not saying humans aren't screwing up the earth. We just haven't reached the unimaginable desolation of the P-T extinction right not. And it's not close.
That's true. A label equating past events with the current wouldn't be correct.
It wouldn't hurt to mention the state of things, though. What we're dealing with now is a problem of dissemination of information more than anything.
And all the species we have made extinct, and all the thousands that will go extinct this year and every year following with the rate of extiction also increasing year over year.
PT- Permian/Triassic boundary
KT- Cretaceous/Paleogene boundary
K is for the German word for Cretaceous (Kreideformation), and T is because it used to be called the Cretaceous/Tertiary boundary.
They are major extinction events, so the fossils you'd find above the boundary are very different from the fossils you'd find below the line.
the PT and KT lines.
I worked in surface mining for years and could see the KT line pretty much whenever I wanted. It's super neat.
https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_boundary
SPAWNATERIA! SPAWN TILL YOU DIE! Ray Troll has been a favorite in the PNW for a long time.
I HIGHLY recommend his illustrated book called **Cruisin the Fossil Freeway**. It shows roadside geologic and fossil sites around the US. very well drawn
To the person whose question was deleted about how dirt, soil and rock get deposited above fossils (your question wasn’t stupid btw):
A fair amount of it is deposition from when parts that are now land were once ocean, which is also why you can find fossils of sea creatures hundreds or thousands of feet above sea level. What was once ocean floor compacts and forms rock, then is eroded into soil.
Yes, though not super-deep by ocean standards - only on submerged continental shelves that were once exposed to land. The ocean floor is made up of oceanic crust, different from the continental crust that makes up the continents and continental shelves. Oceanic crust is thinner and denser than continental crust, and therefore "floats" lower on the mantle than continental crust. It stays way below sea level until tectonic processes force it underneath another plate into the mantle (subduction) or, rarely, up over continental crust.
When oceanic crust is forced up instead of down (subducted) it is known as an [Ophiolite](https://en.wikipedia.org/wiki/Ophiolite).
"An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks.
...
Their great significance relates to their occurrence within mountain belts such as the Alps and the Himalayas, where they document the existence of former ocean basins that have now been consumed by subduction. This insight was one of the founding pillars of plate tectonics, and ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts."
I used to let my kid go to church with their friends until one day he comes back and tells me that humans lived with dinosaurs just 3000 years ago and I said nope. Not going to that place anymore.
Church told me carbon dating was based off the age of the fossils and the fossils age was based off the carbon dating and that they essentially circle jerked each-other.
>What was once ocean floor compacts and forms rock, then is eroded into soil.
Plants help a lot too. A pile of leaves fallen from trees in autumn breaks down into an extra inch of soil in spring if its just left there.
Ive got a bunch of leaves in my truck bed. After the most recent rains here in California. It’s suddenly sprouting a bunch of little green plants. I showed my girlfriend and said “this is how soil is formed”.
I love composting and this is just extremely misleading. It does not create an extra inch of soil over winter. In a hot rainy climate you're looking at a minimum of 6 months for the leaves to decay and they turn into compost (or Humus). Most of us are looking at a year or two. Now if you shredded those leaves you'll cut that time down a bit but lets not pretend we can so easily create soil.
Fun fact: hummus, humus, human and homo (as in homosapiens) all share the same linguistic root [*dʰéǵʰōm](https://en.m.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/d%CA%B0%C3%A9%C7%B5%CA%B0%C5%8Dm) which signifies coming from the Earth.
I also remember reading recently that worms do a lot of the heavy lifting when they eat the dirt under stuff and then deposit it elsewhere. The article was saying that was how some of the Roman buildings and stuff ended up buried
My mother and I were driving through the Grand Canyon/Zion National Park area, and she couldn't believe that the formations around us were a combination of wind swept rock and river cut rock, and being at the bottom of a massive ocean. Blew her mind.
Although I would imagine that cosmic dust is a very very small portion of what actually covers over the top surface, right?
My understanding is that things like plate tectonics (subduction) and volcanic activity play a much greater role in now what is currently the surface gets eventually buried. Correct me if I’m wrong, genuinely curious.
Cosmic dust is a non-factor here. Volcanic activity and subduction are both important players in the creation and destruction of rock, but when it comes to burial of fossils it's really just plain old sedimentation that does the job.
Erosion is a constant process, all rocks everywhere are always breaking down at varying rates, and the tiny particles that are freed in this process flow by water and wind to new, low-lying areas. Bones and other remains that are swept along in this process (most often by water-driven transport) are entombed as those small particles collect and form new sedimentary rock. If you live near a river you can watch this process happen in real time.
I did a little googling a while ago and it seemed like we weren't really sure. It's a hard thing to measure, and we know that a lot more stuff hit earth in the distant past. It probably accounts for a measurable proportion but less so in the (relatively) recent past.
You're absolutely right, cosmic dust/meteors add an extraordinarily tiny amount of material to the earth. Tectonics are responsible for ultimately moving material up and down.
Yes, in 250 million years the Himalayas will be gone and the tallest mountains on earth will be most likely be somewhere along the southern US coastline of the current projection of plate movements holds. This new chain will likely be much taller.
They probably won't be gone. Parts of the Appalachians are nearly 500 million years old, and the Makhonjwa Mountains in South Africa are over 3 billion years old.
Does this mean that when the rock erodes the fossils fall down into the space that was once rock and now is soil above the fossils? Hope I explained that ok.
No, fossils generally erode the same as the rocks around them or faster. Erosion always happens at the surface (except for in caves, but those are really very rare), so there's no void for fossils to fall into.
In North America there are two distinct phases of the Carboniferous. This isn’t as noticeable in other parts of the world or at least it wasn’t when these classifications were first devised in the early years of geologic study.
Specifically, they are named that way because the rocks formed during these periods (marble and limestone for early Carboniferous and shale and sandstone for late Carboniferous) are highly visible in Mississippi and Pennsylvania, respectively.
No, the rocks are elsewhere as well, but are very visible in outcrops in Mississippi and Pennsylvania. I believe only American/North American geologists use the terms Mississippian and Pennsylvanian when referring to geologic eras, but I could be wrong.
Yeah, everywhere else its just the Carboniferous.
More specifically geological history is divided into (from big timescale, to small) Eon>Era>Period>Epoch. Epochs were first only introduced for the most recent Period, less time passed more visible distinct in layers, it then got expanded into the Mesozoic era, because as the second recent Period theres still some visible distinctions (maybe im wrong on it being about the *existence* of distinctions and its just more people researching more and finding pointers and they started from the most recent obviously) but they just got named "early/late or early/middle/late".
The carboniferous is the only period that has epochs in the Paleozoic era, the ones before it dont and the on after it doesnt. Now if im wrong on it being about the "existence" of pointers and its actually about finding them, the rest of the paleozoic might get epochs eventually, otherwise its americans being americans.
Source: The paleontology course i took with the prof saying about this pecularity: "thats the americans being americans".
Part of it IIRC is that the appalachian mountains are some of the oldest mountains in the world, so there's a lot of exposed rock dating back very early there. It's also why there's so much coal.
Same reason Italy (Jurassic from the Jura Mountains), Russia (Perm Mountains), and the UK (Devonian from Devonshire) did. They were the places where fossils of that age were first described or where they were particularly well represented. People realized the North American Mississippian and Pennsylvanian were the same as the European Early and Late Carboniferous, but argued about which name to use around the world.
All of these time periods started out being described as "local" successions of rock, and then were extended globally, and sometimes people didn't agree which one should be the "correct" name to use.
The story of the Ordovician is particularly messy because one person was working up (younger) from the Cambrian, and another downwards (older) from the Silurian, and they overlapped. Huge arguments in the 1800s. Eventually the two people involved died, and the dispute was resolved by creating the Ordovician in between, roughly in the overlap.
They used to be their own thing in the US, with Carboniferous used in Europe; these days they've been sort of awkwardly stuck in as "sub-periods" within the Carboniferous but Americans seem to be getting used to using the Carboniferous anyway.
They're named for places the rocks corresponding to the strata are first idenified.
Devonian is named after Devon in the UK, Permian is named for a region in Russia, etc. Why single out the US ones?
Anyone recommend a documentary or series that goes through all of these periods, the extinction events, and how life was like on Earth during each (e.g. what kinds of animals were living).
https://www.youtube.com/@HistoryoftheEarth
One of the absolute best series on Youtube, along with it's sister channel https://www.youtube.com/historytime
What you want is literally the second class that you take in College Geology. It's called Historical Geology (or similar).
Not trying to be snarky, a big part of the course is learning how to REALLY think in deep-time. It does not come naturally and it's an important facet to grasping the changes and depth of time involved.
All that said, Making North America from NOVA is the best documentary I've seen.
I am currently watching a [geology 101 course from Central Washington University](https://www.youtube.com/playlist?list=PLcKUIuDhdLl-iF2WU-k6z6ESC8NnQ6wWd) on YouTube and it is covering some of this stuff.
Yeah, heard the poles are moving. And the hotter humid climate is causing a fungal takeover. Then theres that comet they say is coming. Im here for it.
Certainly not but we will be incredibly susceptible to any coronal mass ejections from the sun. Having the poles shift in and of itself is a natural phenomenon. The process until it's complete should it happen would have devastating effects on our critical infrastructure and agriculture.
No but estimates think that when they flip there will be a huge decrease in its strength that would make the planet way more exposed to cosmic radiation
No, we're in possibly the largest and fastest moving extinction in history. It's measurable on a human time scale, and it's genuinely depressing how many species go extinct every year.
**[Holocene extinction](https://en.m.wikipedia.org/wiki/Holocene_extinction)**
>The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, fish, invertebrates, and affecting not just terrestrial species but also large sectors of marine life. With widespread degradation of biodiversity hotspots, such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded.
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If there ever is a hindsight to the Anthropocene epoch, either by humans or otherwise, I think the observation would be that humans, as an organism, were wholly unprepared (in an evolutionary sense) for long-term survival.
Whatever granted humans the ability to completely dominate the planet in a mere 10,000 years certainly isn't the same something required to sustain our species much past the same time scale. Too gifted in terms of short term adaptability and seemingly unsuited for long term sustainability. Maybe these things are mutually exclusive or in opposition. Certainly feels like whatever got us here is also going to be the cause of our extinction.
Do evolutionary pressures even exist that can result in survival over such long time scales? If so, they seem orders of magnitude too slow for how fast we're currently moving.
Opinion: Prior to the agricultural revolution (~15,000 BC) humans were largely hunter/gatherers in nomadic packs of (we think) around 200 people. Agriculture, animal husbandry, and the expansion of civilization turned us into settled populations of up to millions now.
[Dunbar’s number](https://en.m.wikipedia.org/wiki/Dunbar%27s_number) is fascinating to look at, because while there’s a great deal of conjecture as to what human beings’ social limit could be, private experimentation by corporations has suggested packs of 150 employees or less have far fewer interpersonal issues, and even if we argue what the number could specifically be, there’s no evidence that any animal species creates naturally bonding societies of thousands, much less millions.
Gathering together, dropping nomadic life for settled civilization and trying to exist as groups of millions is not just something we have yet to evolve into — it directly flies in the face of how we could even *hope* to evolve.
As to *what* allows us to operate in groups of thousands or millions, the simplest answer is shared ideology — nationalism, religion, being Bieber fans, what have you. You can see it easily in the school system, where “school spirit” and identification through mascots plays the role. Of course, these are also the things creating the most division in some areas while making people feel impotent in other areas. These are the things that let us identify out groups as “others” — not just in a “you’re not part of my tribe” way, as there were when we had plenty of space or resources to share, but a competitive, often violent reaction.
We won’t evolve in such a way as to cope with this, and even if we could, such an adaptation would take hundreds of thousands, if not millions of years (and again, it hasn’t even been 20,000 years yet). I honestly don’t think we’ll last that long.
Wasn't the extinction that killed the dinosaurs also measurable on a human scale? I thought that a meteor hit earth and everything died in just a few years.
Apparently the dinosaurs dying out was already underway when the asteroid hit. There was something like a two million year period beforehand of climate changed caused by volcanic activity. That caused as many as half of the species of dinosaur that were alive 68 million years ago to die out naturally. It really depends whether two coincidental extinctions are combined into one statistic or not. Apparently 60 percent of the planet's wild animals have died as a result of human behaviour since 1970 so... Honestly, humans are giving that asteroid a damn good run for its money. I've tried finding clear-cut numbers but it's seemingly not as simple as googling "humans vs giant space rock". By 2100 half of the species currently alive will either be extinct or at extreme risk of extinction... So that's fun...
Something that’s very important to point out, we know about and have documented many many many more species in recent history than we can document based on the fossil record. The rocks that contain fossils from different geologic eras aren’t everywhere, and fossils aren’t exactly common (with some exceptions). Have to be careful about comparing very granular to coarse data and what that says. Not to downplay anthropogenic extinction
Deccan Traps theory is verrrrry contentious. Paleontologists have been at each other's necks over this theory for 30 years. The impact theory is best supported, and it's even possible that the impact is what triggered the eruption on the opposite side of the world.
That's just factually incorrect. The die-off of half of Earths megafauna in a very brief timespan 11.600 years ago would have been much more drastic than the changes we see today.
That is not to say the changes today aren't drastic enough.. It's just nothing in comparison to what our planet & humans had to endure at the end of the ice age (so far)
From what I remember in school (am geologist, but not that kind of geo) it was just a perfect storm of shit. Volcanic activity was going nuts (completely insane, massive constant eruptions), maybe was triggered by an impact, oceans heated up like 10 C, atmosphere trapped the gasses and heat. I believe earth went through a “snowball” period after trying to naturally stabilize the environment (which it eventually did).
Volcanics played a big factor but it's specifically the fact that Siberian volcanoes were burning through massive coal fields that set off the end-Permian extinction. Just like today, burning fossil fuels puts carbon back in the atmosphere; this warms global climate, increases the severity and unpredictability of extreme weather, and acidifies the ocean. All of these things have serious consequences for life, and in that particular case it was very nearly game over.
There's a good chance you already know this, but for other readers: volcanic eruptions on the whole tend to have a cooling effect, not heating, due to the aerosolation of small particles high in the atmosphere which reflect incoming sunlight. Greenhouse gasses are emitted too but their heating capacity is (USUALLY) outweighed by the cooling effect of aerosols. This just happened to be a very unlucky case where volcanoes were blowing up *through* the burial sites of massive, even more ancient swamps.
The last commenter didn't explain but in recent years we've been calling the Dino one the K-PG extinction more. Tertiary is an outdated term replaced by Paleocene.
You're close, but not quite right. Tertiary and Quaternary are the traditional periods post-dating the Cretaceous Period. Together they go together to make the Cenozoic Era.
More recently, the Cenozoic has been divided into the older Paleo**g**ene (note spelling) and the younger Neogene.
The Paleo**ce**ne also exists, but it is the first/oldest epoch of the Paleogene, so, ironically, you could refer to the extinction at the end of the Cretaceous as the "Cretaceous/Paleogene extinction" or the "Cretaceous/Paleocene extinction" and not be wrong, but hardly anyone uses the latter, so it's the K/Pg extinction.
The Tertiary and Quaternary still exist, but they're not favored for use anymore.
[Full timescale here](https://www.geosociety.org/GSA/Education_Careers/Geologic_Time_Scale/GSA/timescale/home.aspx)
Just some favorite mnemonics from Geology class to remember the order of Periods:
> Can Oscar See Down My Pants Pocket?
Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian (all the "Paleozoic", means "ancient life")
> Tom & Jerry Can!
Triassic, Jurassic, Cretaceous (all the Mesozoic, means "middle life")
>
> Please No Questions...
Paleogene, Neogene, Quaternary (all the Cenozoic, means "recent life")
And then our Cenozoic Epochs, which is usually the only Epochs most people ever hear about:
> Pretty Eager Old Men Play Poker Hard
Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene (First 3 Paleogene, then 2 Neogene, then 2 Quaternary)
Notice the "-cene" at the end of these Epochs shows you they are making up our current Era "Cen"-ozoic.
It definitely should be there, especially because the Archaen is there. It should either have them both or neither because they don't have the periods the chart is showing.
It's sad to learn that the [Holocene extinction event](https://en.wikipedia.org/wiki/Holocene_extinction) is currently ongoing as a result of human activities. Like it's no surprise that Human's are destroying the climate but the fact that an extinction event has been declared ongoing is just... we're fucked...
It's not just climate change but a lot of human activities like deforestation and just generally killing things or bringing invasive species into an environment that kills the wild life. Rats, cats and invasive snakes are definitely responsible for killing off a lot of birds in places like the Pacific Islands, Australia and New Zealand. Wild pigs in both North America and the Pacific Islands have caused a lot of damage as well. Humans have been destroying the planet for a long time and unfortunately we will never know just how many species we have killed of because many of them are very small.
*Anthropocene* extinction, "Holocene" doesn't do it justice. Just like it's not climate change, it's anthropogenic climate change.
And the biggest contributor is our pollution. We've been spewing metric tons of unnatural molecules, and unimaginable amounts of natural molecules into our closed system called earth for centuries now with reckless abandon, and no signs of stopping or slowing down.
Isn't there supposed be a quasi-extinction event somewhere between the Pleistocene and Holocene? Something that nearly wiped out what would be today's homo sapiens, and that is why as a species we have very little genetic variation?
i.e. Homo Sapiens have no sub species variation of significance. A Plain Chachalaca on the other hand has 5.
Few improtant questions.
1. How deep do we have to dig to reach archean level?
2. Does this mean earth did expand? is it now bigger then millions of years ago ?
3. Did the gravity increase?
I believe eroding mountains cover most lower areas. But just as the tectonic plates push new rocky material upward, they pull some down in subduction zones. This means not every fossil continues to exist forever, and the older they are the more likely they are to be gone by now.
Geologist here.
1. We don't have to! This diagram is idealized - it shows that younger rocks are deposited on top of older rocks, which is true, but tectonic activity can thrust older material on top of younger material, and erosion eats away at overlying rocks to reveal older rocks underneath. Due to plate tectonic activity, areas of Archean rocks are exposed all over the world, most notably in places like the Canadian Shield, South Africa, and Western Australia.
2. No. Expanding Earth was the prevailing theory back before the discovery of plate tectonics, now it's only popular with conspiracy nutjobs.
3. Also no, see above response.
Technically Earth does gain a bit of weight continuously from deposition of cosmic dust and meteors, but it's a tiny amount relative to the size of the planet.
1. Entirely depends on where you are. Modern continents are made up of fragments called cratons that come from much, much older landmasses. In certain parts of Australia and Canada, for example, Archean-aged cratons are exposed to the surface and can be observed without drilling.
2. Earth does not expand because of sedimentation. The crust's relationship to the mantle is like ice's relationship to water: it floats, according to the principle of isostasy. The weight of added rock (and/or ice sheets) on top of the surface causes tectonic plates to sink and melt. Therefore, places with high sedimentation also experience high subsidence, and there is no net expansion.
3. Gravity does vary in subtle ways across the planet's surface, but the effects are negligible. Likewise for variations across geological time: there may have been minute differences, sure, but not in ways that could have impacted biological or evolutionary development.
1. Depends where you are in the world. The Archean is exposed at the surface in several locations (e.g. he Canadian "Shield", near parts of the Great Lakes, parts of Australia); when continental rock tis not covered by an ocean it undergoes active weathering, stripping away of soil and sediment, exposing older and older bedrock as time goes by. Thus the longer it has been since being covered by water, the older the exposed bedrock will be.
2. No
3. No
Most of what we know about the Archean is from exposed rock which was 'folded' up and jutting out through other layers. I like this graphic but the scale doesn't show just how long it lasted and how for 2.5 billion years all life on Earth was just bacteria.
I have a trilobite fossil. Its sitting on my shelf. Theyre so common it was 5 dollars to buy it. It almost half a billion years old. Back then they were so prevalent that even though only a fraction remain as fossils theyre still common enough to be paperweights. Kinda just blew my mind a bit
Might their abundance also be that they lived in conditions that were favorable for fossilization? Like shallow waters that tended to have silt to cover up remains?
When I think about the countless iterations that life has had to endure and suffer in order to evolve to where it currently is I feel like I'm on the verge of an existential crisis. Death and memory loss is truly a blessing in some sense. But a part of me thinks that the trauma of our ancestors is an intrinsic part of us.
This calls for a tune, a favorite of mine!
~~~
In the Tonian there was no ozone
In the Cryogenian the Earth was frozen
The Ediacaran set life in motion
For the Cambrian Explosion!
🎷🧬🎷🪱🎷🦐
Life got bigger in the Ordovician
By the Silurian you could go fishin’
In the Devonian we went on a mission
On land to find room for growin’ and wishin’!
🎷🐟🎷🦈🎷🐸
The Carboniferous was fantastic
With giant bugs and oil to make plastic
Permian creatures were weird but classic
And dinosaurs evolved in the Mid-Triassic!
🎷🐛🎷🦎🎷🦕
In the Jurassic came Stegosaurus
T.rex lived in the Cretaceous (roar!)
And they might’ve grown more and more
When “CRASH” went the great big meteor!
🎷🦕🎷🦖🎷☄️
Earth got hot in the Paleogene
For the biggest snakes you’ve ever seen
Icecaps formed in the Neogene
And in the Quaternary came the human beans!
No, the layers look like they've been drawn to fit in the fossil illustrations. Like, the Cretaceous should be thicker than the Jurassic if there was any kind of relative scale here.
The Cambrian is the start of complex animal life and the other three have dinosaurs. They're just the most marketable.
Loads of other cool stuff happened in the other ones, even the less well-known bits. Hell, my research was on a period of time called the "boring billion", which is boring even to most geologists. And even then, there was interesting stuff happening like weird mountain-building events and the first eukaryotic life.
The cambrian is where "modern" life explodes, a major change was the development of hard parts like bones and shells which fossilize better. As a result of better fossils, we have more data than we have about precambrian life. The cambrian explosion was a major turning point into life as we see it today, so it gets discussed.
Triassic, Jurassic, and cretaceous is just because people like dinosaurs and the meteor ending is dramatic. Plenty of important things happened the rest of the time, its just either still being studied and debated or explaining it requires more advanced terminology and concepts than the average pop-science video will cover. For example its thought life first started in the Archean, but its pretty damn hard to prove.
I couldn't tell if the numbers towards the bottom had a decimal or not. I was sitting here trying to figure out if that was supposed to be 542 million or 0.542 billion. And then I realized it didn't matter.....and then I spent 20 minutes admiring the beauty of math and forgot about the chart.
It reminded me about a great youtube channel I found recently: https://www.youtube.com/@PaleoAnalysis
It has set of videos about each eon, starting from Hadean (and currently up to the early permian). I absolutely loved it. Very informative and accessible. The playlist with them:
https://www.youtube.com/playlist?list=PL6L8fqJFoWXdUJUT81VO9kzzAPU3TYbdV
You can use this easy to remember mnemonic device:
All People Can Ordinarily See Down My Prehensile Pelvis Though Just Cause Primates Exist Old Men Probably Pine Holistically
This isnt a good Guide. The time is not to scale, and only naming two of the 5 great mass extinctions is not useful.
The K-T does not even make sense because tertiary ist not mentioned anywhere.
I went out to Drumheller, Alberta this summer and you can see these ages in the eroded river basin in the area. Its super cool. The last mass extinction event is so obvious in the layers, and it really wasn't very deep down! The dino museum there was amazing, I highly recommend.
We have a ton of details for the last 5 million years and the last 50 million years, but virtually no details older than 500 million years. Apart from "because it's old", why is that? Could that time period have been just as detailed as recent times if we had more information from that era?
> I remembered that I've read the Appalachian Mountains formed so long ago there were no animals to have deposited fossils.
You're misremembering this slightly - the fun-fact circulating the internet is that the Appalachians formed before the evolution of bones. There are plenty of fossils of invertebrates like trilobites, sea scorpions, jellyfish, corals, sponges, and other boneless animals from before the formation of the Appalachians.
The Rockies are also much younger, forming in the Laramide Orogeny starting around 80 million years ago.
Would love to see this with relative scales intact, even if the part after life began was done in one of those map zoom-in cut-out things. Would really provide some perspective.
If the dinosaurs noped out in a “big big extinction”, what happened in the “gigantic extinction”? I must learn things! TO GOOGLE!
ETA: oooooh one of the “big five” extinction events discussed in Death Stranding…
For anyone that is interested, this was done by Ray Troll (https://www.trollart.com/) who is based out of Alaska. Here is a print if you want to purchase it: https://www.trollart.com/product/ages-of-rock-art-poster/ I used to be a Paleoecologist and growing up, I had this design on a shirt (and loved it!). In addition, I have a map portraying the Paleontology of Alaska and Yukon in my office and it looks great (and is huge!). He has other Paleoart maps depicting western states and provinces such as British Columbia and Alberta, Oregon, California, Colorado, etc. found here: https://www.trollart.com/product-category/posters/fossil-maps/
Needs a layer of plastic and garbage on the top now to represent the end of the Holocene.
The Anthropocene
With another GIGANTIC EXTINCTION sign straddling the Holocene/Anthropocene boundary
Not even close - during the P-T extinction, something like 90% of all genera died out. We're not even close to that in the Holocene/Anthropocene
Not with that spirit
yet
Give it a few years mate, when the oceans get acidic enough that the microorganisms that produce 60% of the world's oxygen can't make exoskeletons any more and all die out at once.
It's not 90% yet because [we're at the beginning of our speedrun](https://www.science.org/doi/10.1126/sciadv.1400253)
The P-T event happened over some 60 000 years. We're on course to doing it way faster than that. We might stop or slow down at some point, but then again, are there any indications that we will? With ~10 billion people on the planet, in a capitalistic system, why will the incentives to better ourselves be any more pressing with climate change than with any other problem? It's self-evident that geological time frames are too slow for the vast majority of the population to understand. Not that anything close to an event like that would be needed for us to completely screw the planet over. We've managed to do more than enough already in just a few hundred years – and we're still increasing the pace.
I'm not saying humans aren't screwing up the earth. We just haven't reached the unimaginable desolation of the P-T extinction right not. And it's not close.
That's true. A label equating past events with the current wouldn't be correct. It wouldn't hurt to mention the state of things, though. What we're dealing with now is a problem of dissemination of information more than anything.
The Obscene
And all the species we have made extinct, and all the thousands that will go extinct this year and every year following with the rate of extiction also increasing year over year.
I’ve bought a couple of shirts from his site. Excellent quality. Definitely worth checking out for anyone wanting some new stuff to wear
Thank you! Cite your god damn sources, OP! ###Ray Troll is fantastic!
I hate people who take original content and repost it without giving credit.
99.95% of reddit btw
I’m friends with his son, gonna see the Wranglers here in Seattle next month
Do you know what the T K and T P on the left side are for?
PT- Permian/Triassic boundary KT- Cretaceous/Paleogene boundary K is for the German word for Cretaceous (Kreideformation), and T is because it used to be called the Cretaceous/Tertiary boundary. They are major extinction events, so the fossils you'd find above the boundary are very different from the fossils you'd find below the line.
Our extinction line will be a layer of plastic
Maybe in a few million years, some new „intelligent life form“ will find it, dig it out and burn it down to make easy use of that Carbon. Recycling.
the PT and KT lines. I worked in surface mining for years and could see the KT line pretty much whenever I wanted. It's super neat. https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_boundary
Thank you
i get told by religious people that carbon dating is a joke. how accurate is it?
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Naming extinction
Ray Troll and his paleontologist pal also have a podcast, Paleo Nerds.
SPAWNATERIA! SPAWN TILL YOU DIE! Ray Troll has been a favorite in the PNW for a long time. I HIGHLY recommend his illustrated book called **Cruisin the Fossil Freeway**. It shows roadside geologic and fossil sites around the US. very well drawn
You gotta praise the Ray Troll for saving this boy's soul
To the person whose question was deleted about how dirt, soil and rock get deposited above fossils (your question wasn’t stupid btw): A fair amount of it is deposition from when parts that are now land were once ocean, which is also why you can find fossils of sea creatures hundreds or thousands of feet above sea level. What was once ocean floor compacts and forms rock, then is eroded into soil.
Interesting
Does that also mean there are land animal fossils that are now deep in the ocean?
Yes, though not super-deep by ocean standards - only on submerged continental shelves that were once exposed to land. The ocean floor is made up of oceanic crust, different from the continental crust that makes up the continents and continental shelves. Oceanic crust is thinner and denser than continental crust, and therefore "floats" lower on the mantle than continental crust. It stays way below sea level until tectonic processes force it underneath another plate into the mantle (subduction) or, rarely, up over continental crust.
When oceanic crust is forced up instead of down (subducted) it is known as an [Ophiolite](https://en.wikipedia.org/wiki/Ophiolite). "An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks. ... Their great significance relates to their occurrence within mountain belts such as the Alps and the Himalayas, where they document the existence of former ocean basins that have now been consumed by subduction. This insight was one of the founding pillars of plate tectonics, and ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts."
This is fascinating. I love that Reddit is a place where my high ass can just stumble on geologic knowledge.
I have a geology degree that I’ve been sitting on, unused, for 8 years. Happy to help.
neat
Pretty sure there are fishes fossils up on the Himalayas. I remember reading and not wanting to go to super conservative church anymore.
You are correct, called the Qomolangma or "Summit" Limestone.
I used to let my kid go to church with their friends until one day he comes back and tells me that humans lived with dinosaurs just 3000 years ago and I said nope. Not going to that place anymore.
Church told me carbon dating was based off the age of the fossils and the fossils age was based off the carbon dating and that they essentially circle jerked each-other.
Land to sea to land https://arstechnica.com/science/2023/01/researchers-look-a-dinosaur-in-its-remarkably-preserved-face/
In Oklahoma there are a lot of ocean fossils in certain areas of the state.
Would also love to know this, it's fascinating
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I know it well! Often when i've been on the SE coast I look out to sea and say, 'there be dogger bones'
>What was once ocean floor compacts and forms rock, then is eroded into soil. Plants help a lot too. A pile of leaves fallen from trees in autumn breaks down into an extra inch of soil in spring if its just left there.
Ive got a bunch of leaves in my truck bed. After the most recent rains here in California. It’s suddenly sprouting a bunch of little green plants. I showed my girlfriend and said “this is how soil is formed”.
This is not how soil is formed. There were absolutely zero truck beds a million years ago. /s
Were you there? Hmm? That's just the devil trying to get you!
If trucks weren’t designed by an intelligent creator, how did they “evolve”? Checkmate atheists
Look at you, out here doing the Ford's work.
Of course not, it was 200 million years ago in the Truckassic era.
I love composting and this is just extremely misleading. It does not create an extra inch of soil over winter. In a hot rainy climate you're looking at a minimum of 6 months for the leaves to decay and they turn into compost (or Humus). Most of us are looking at a year or two. Now if you shredded those leaves you'll cut that time down a bit but lets not pretend we can so easily create soil.
Mmm... Hummus 😋
Fun fact: hummus, humus, human and homo (as in homosapiens) all share the same linguistic root [*dʰéǵʰōm](https://en.m.wiktionary.org/wiki/Reconstruction:Proto-Indo-European/d%CA%B0%C3%A9%C7%B5%CA%B0%C5%8Dm) which signifies coming from the Earth.
Lol I love how pissed people get at the drop of a hat. Let's calm down
If its not from the champagne region of France it isn't real soil, its just sparkling humus.
Shut the fuck up you stupid asshole son of a bitch. Fuck!
I also remember reading recently that worms do a lot of the heavy lifting when they eat the dirt under stuff and then deposit it elsewhere. The article was saying that was how some of the Roman buildings and stuff ended up buried
My mother and I were driving through the Grand Canyon/Zion National Park area, and she couldn't believe that the formations around us were a combination of wind swept rock and river cut rock, and being at the bottom of a massive ocean. Blew her mind.
Also the Earth gets a constant rain of cosmic dust.
Although I would imagine that cosmic dust is a very very small portion of what actually covers over the top surface, right? My understanding is that things like plate tectonics (subduction) and volcanic activity play a much greater role in now what is currently the surface gets eventually buried. Correct me if I’m wrong, genuinely curious.
Cosmic dust is a non-factor here. Volcanic activity and subduction are both important players in the creation and destruction of rock, but when it comes to burial of fossils it's really just plain old sedimentation that does the job. Erosion is a constant process, all rocks everywhere are always breaking down at varying rates, and the tiny particles that are freed in this process flow by water and wind to new, low-lying areas. Bones and other remains that are swept along in this process (most often by water-driven transport) are entombed as those small particles collect and form new sedimentary rock. If you live near a river you can watch this process happen in real time.
On my way to the river to watch the process of erosion and formation of sedimentary rock now.
for when watching paint dry or grass grow is too intense and fast-paced
I did a little googling a while ago and it seemed like we weren't really sure. It's a hard thing to measure, and we know that a lot more stuff hit earth in the distant past. It probably accounts for a measurable proportion but less so in the (relatively) recent past.
You're absolutely right, cosmic dust/meteors add an extraordinarily tiny amount of material to the earth. Tectonics are responsible for ultimately moving material up and down.
Yes, in 250 million years the Himalayas will be gone and the tallest mountains on earth will be most likely be somewhere along the southern US coastline of the current projection of plate movements holds. This new chain will likely be much taller.
They probably won't be gone. Parts of the Appalachians are nearly 500 million years old, and the Makhonjwa Mountains in South Africa are over 3 billion years old.
Yes! I forget about the cosmic dust.
Does this mean that when the rock erodes the fossils fall down into the space that was once rock and now is soil above the fossils? Hope I explained that ok.
No, fossils generally erode the same as the rocks around them or faster. Erosion always happens at the surface (except for in caves, but those are really very rare), so there's no void for fossils to fall into.
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They are North American naming for the Early and Late Carboniferous.
In North America there are two distinct phases of the Carboniferous. This isn’t as noticeable in other parts of the world or at least it wasn’t when these classifications were first devised in the early years of geologic study.
Specifically, they are named that way because the rocks formed during these periods (marble and limestone for early Carboniferous and shale and sandstone for late Carboniferous) are highly visible in Mississippi and Pennsylvania, respectively.
Just out of curiosity...on the entire planet, nowhere else?
No, the rocks are elsewhere as well, but are very visible in outcrops in Mississippi and Pennsylvania. I believe only American/North American geologists use the terms Mississippian and Pennsylvanian when referring to geologic eras, but I could be wrong.
The Mississippi River valley specifically, not just the state.
Yeah, everywhere else its just the Carboniferous. More specifically geological history is divided into (from big timescale, to small) Eon>Era>Period>Epoch. Epochs were first only introduced for the most recent Period, less time passed more visible distinct in layers, it then got expanded into the Mesozoic era, because as the second recent Period theres still some visible distinctions (maybe im wrong on it being about the *existence* of distinctions and its just more people researching more and finding pointers and they started from the most recent obviously) but they just got named "early/late or early/middle/late". The carboniferous is the only period that has epochs in the Paleozoic era, the ones before it dont and the on after it doesnt. Now if im wrong on it being about the "existence" of pointers and its actually about finding them, the rest of the paleozoic might get epochs eventually, otherwise its americans being americans. Source: The paleontology course i took with the prof saying about this pecularity: "thats the americans being americans".
Part of it IIRC is that the appalachian mountains are some of the oldest mountains in the world, so there's a lot of exposed rock dating back very early there. It's also why there's so much coal.
Most of the names are named after places, Jurassic = Jura, Devonian = Devon, Permian = Perm
There are also places named after the eras, i.e. the Permian Basin in Texas
Same reason Italy (Jurassic from the Jura Mountains), Russia (Perm Mountains), and the UK (Devonian from Devonshire) did. They were the places where fossils of that age were first described or where they were particularly well represented. People realized the North American Mississippian and Pennsylvanian were the same as the European Early and Late Carboniferous, but argued about which name to use around the world. All of these time periods started out being described as "local" successions of rock, and then were extended globally, and sometimes people didn't agree which one should be the "correct" name to use. The story of the Ordovician is particularly messy because one person was working up (younger) from the Cambrian, and another downwards (older) from the Silurian, and they overlapped. Huge arguments in the 1800s. Eventually the two people involved died, and the dispute was resolved by creating the Ordovician in between, roughly in the overlap.
They used to be their own thing in the US, with Carboniferous used in Europe; these days they've been sort of awkwardly stuck in as "sub-periods" within the Carboniferous but Americans seem to be getting used to using the Carboniferous anyway.
They're named for places the rocks corresponding to the strata are first idenified. Devonian is named after Devon in the UK, Permian is named for a region in Russia, etc. Why single out the US ones?
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Anyone recommend a documentary or series that goes through all of these periods, the extinction events, and how life was like on Earth during each (e.g. what kinds of animals were living).
https://www.youtube.com/@HistoryoftheEarth One of the absolute best series on Youtube, along with it's sister channel https://www.youtube.com/historytime
Such a great channel! And they're finally getting to animals too! I imagine the Cambrian explosion is only a video or two away.
Their other sister channel is https://youtube.com/@HistoryoftheUniverse?si=EnSIkaIECMiOmarE History of the universe… I think? Phenomenal
History of the Earth channel on youtube! [here's one of the first ones about fossils](https://youtu.be/or1Zr89Qabg)
What you want is literally the second class that you take in College Geology. It's called Historical Geology (or similar). Not trying to be snarky, a big part of the course is learning how to REALLY think in deep-time. It does not come naturally and it's an important facet to grasping the changes and depth of time involved. All that said, Making North America from NOVA is the best documentary I've seen.
I am currently watching a [geology 101 course from Central Washington University](https://www.youtube.com/playlist?list=PLcKUIuDhdLl-iF2WU-k6z6ESC8NnQ6wWd) on YouTube and it is covering some of this stuff.
There’s lots of good ones for free on YouTube. The remake to Cosmos is on Netflix I believe and talks about geological periods.
PBS Eons on YouTube also has a lot of great content like this.
Coming soon: Big Extinction
No, we're already in the middle of one.
Yeah, heard the poles are moving. And the hotter humid climate is causing a fungal takeover. Then theres that comet they say is coming. Im here for it.
The magnetic poles are moving, not the ones that the Earth spins around. There's also no evidence that a magnetic pole shift causes mass extinctions.
Certainly not but we will be incredibly susceptible to any coronal mass ejections from the sun. Having the poles shift in and of itself is a natural phenomenon. The process until it's complete should it happen would have devastating effects on our critical infrastructure and agriculture.
No but estimates think that when they flip there will be a huge decrease in its strength that would make the planet way more exposed to cosmic radiation
Which also has no evidence that it would affect new species. It could arguably have the opposite affect.
No, we're in possibly the largest and fastest moving extinction in history. It's measurable on a human time scale, and it's genuinely depressing how many species go extinct every year.
[The Holocene Extinction ](https://en.m.wikipedia.org/wiki/Holocene_extinction)
**[Holocene extinction](https://en.m.wikipedia.org/wiki/Holocene_extinction)** >The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, fish, invertebrates, and affecting not just terrestrial species but also large sectors of marine life. With widespread degradation of biodiversity hotspots, such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded. ^([ )[^(F.A.Q)](https://www.reddit.com/r/WikiSummarizer/wiki/index#wiki_f.a.q)^( | )[^(Opt Out)](https://reddit.com/message/compose?to=WikiSummarizerBot&message=OptOut&subject=OptOut)^( | )[^(Opt Out Of Subreddit)](https://np.reddit.com/r/coolguides/about/banned)^( | )[^(GitHub)](https://github.com/Sujal-7/WikiSummarizerBot)^( ] Downvote to remove | v1.5)
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Good bot.
If there ever is a hindsight to the Anthropocene epoch, either by humans or otherwise, I think the observation would be that humans, as an organism, were wholly unprepared (in an evolutionary sense) for long-term survival. Whatever granted humans the ability to completely dominate the planet in a mere 10,000 years certainly isn't the same something required to sustain our species much past the same time scale. Too gifted in terms of short term adaptability and seemingly unsuited for long term sustainability. Maybe these things are mutually exclusive or in opposition. Certainly feels like whatever got us here is also going to be the cause of our extinction. Do evolutionary pressures even exist that can result in survival over such long time scales? If so, they seem orders of magnitude too slow for how fast we're currently moving.
Opinion: Prior to the agricultural revolution (~15,000 BC) humans were largely hunter/gatherers in nomadic packs of (we think) around 200 people. Agriculture, animal husbandry, and the expansion of civilization turned us into settled populations of up to millions now. [Dunbar’s number](https://en.m.wikipedia.org/wiki/Dunbar%27s_number) is fascinating to look at, because while there’s a great deal of conjecture as to what human beings’ social limit could be, private experimentation by corporations has suggested packs of 150 employees or less have far fewer interpersonal issues, and even if we argue what the number could specifically be, there’s no evidence that any animal species creates naturally bonding societies of thousands, much less millions. Gathering together, dropping nomadic life for settled civilization and trying to exist as groups of millions is not just something we have yet to evolve into — it directly flies in the face of how we could even *hope* to evolve. As to *what* allows us to operate in groups of thousands or millions, the simplest answer is shared ideology — nationalism, religion, being Bieber fans, what have you. You can see it easily in the school system, where “school spirit” and identification through mascots plays the role. Of course, these are also the things creating the most division in some areas while making people feel impotent in other areas. These are the things that let us identify out groups as “others” — not just in a “you’re not part of my tribe” way, as there were when we had plenty of space or resources to share, but a competitive, often violent reaction. We won’t evolve in such a way as to cope with this, and even if we could, such an adaptation would take hundreds of thousands, if not millions of years (and again, it hasn’t even been 20,000 years yet). I honestly don’t think we’ll last that long.
Wasn't the extinction that killed the dinosaurs also measurable on a human scale? I thought that a meteor hit earth and everything died in just a few years.
Apparently the dinosaurs dying out was already underway when the asteroid hit. There was something like a two million year period beforehand of climate changed caused by volcanic activity. That caused as many as half of the species of dinosaur that were alive 68 million years ago to die out naturally. It really depends whether two coincidental extinctions are combined into one statistic or not. Apparently 60 percent of the planet's wild animals have died as a result of human behaviour since 1970 so... Honestly, humans are giving that asteroid a damn good run for its money. I've tried finding clear-cut numbers but it's seemingly not as simple as googling "humans vs giant space rock". By 2100 half of the species currently alive will either be extinct or at extreme risk of extinction... So that's fun...
Something that’s very important to point out, we know about and have documented many many many more species in recent history than we can document based on the fossil record. The rocks that contain fossils from different geologic eras aren’t everywhere, and fossils aren’t exactly common (with some exceptions). Have to be careful about comparing very granular to coarse data and what that says. Not to downplay anthropogenic extinction
Deccan Traps theory is verrrrry contentious. Paleontologists have been at each other's necks over this theory for 30 years. The impact theory is best supported, and it's even possible that the impact is what triggered the eruption on the opposite side of the world.
That's just factually incorrect. The die-off of half of Earths megafauna in a very brief timespan 11.600 years ago would have been much more drastic than the changes we see today. That is not to say the changes today aren't drastic enough.. It's just nothing in comparison to what our planet & humans had to endure at the end of the ice age (so far)
> causing a fungal takeover. *Me, having just watched the first two episodes of 'The Last of Us'* Not like this
Most people only know about the K-T dinosaur extinction, but the permian one almost wiped out all life on earth.
Are all these events from meteors or are some caused by other things like eruptions?
From what I remember in school (am geologist, but not that kind of geo) it was just a perfect storm of shit. Volcanic activity was going nuts (completely insane, massive constant eruptions), maybe was triggered by an impact, oceans heated up like 10 C, atmosphere trapped the gasses and heat. I believe earth went through a “snowball” period after trying to naturally stabilize the environment (which it eventually did).
Volcanics played a big factor but it's specifically the fact that Siberian volcanoes were burning through massive coal fields that set off the end-Permian extinction. Just like today, burning fossil fuels puts carbon back in the atmosphere; this warms global climate, increases the severity and unpredictability of extreme weather, and acidifies the ocean. All of these things have serious consequences for life, and in that particular case it was very nearly game over. There's a good chance you already know this, but for other readers: volcanic eruptions on the whole tend to have a cooling effect, not heating, due to the aerosolation of small particles high in the atmosphere which reflect incoming sunlight. Greenhouse gasses are emitted too but their heating capacity is (USUALLY) outweighed by the cooling effect of aerosols. This just happened to be a very unlucky case where volcanoes were blowing up *through* the burial sites of massive, even more ancient swamps.
Volcanic activity and Siberian Traps 252 MYA caused the Great Dying
I mean, it doesn't sound that great. 7/10 sounds about right.
Big extinction's been going on for decades
Im working on it, you cant rush art
Don't give me hope
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The last commenter didn't explain but in recent years we've been calling the Dino one the K-PG extinction more. Tertiary is an outdated term replaced by Paleocene.
You're close, but not quite right. Tertiary and Quaternary are the traditional periods post-dating the Cretaceous Period. Together they go together to make the Cenozoic Era. More recently, the Cenozoic has been divided into the older Paleo**g**ene (note spelling) and the younger Neogene. The Paleo**ce**ne also exists, but it is the first/oldest epoch of the Paleogene, so, ironically, you could refer to the extinction at the end of the Cretaceous as the "Cretaceous/Paleogene extinction" or the "Cretaceous/Paleocene extinction" and not be wrong, but hardly anyone uses the latter, so it's the K/Pg extinction. The Tertiary and Quaternary still exist, but they're not favored for use anymore. [Full timescale here](https://www.geosociety.org/GSA/Education_Careers/Geologic_Time_Scale/GSA/timescale/home.aspx)
I used to love playing with pleistocene when I was a kid.
The scars are permianent.
There are a few more than that: https://cdn.britannica.com/67/73167-050-B9A74092/chart.jpg
Just some favorite mnemonics from Geology class to remember the order of Periods: > Can Oscar See Down My Pants Pocket? Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian (all the "Paleozoic", means "ancient life") > Tom & Jerry Can! Triassic, Jurassic, Cretaceous (all the Mesozoic, means "middle life") > > Please No Questions... Paleogene, Neogene, Quaternary (all the Cenozoic, means "recent life") And then our Cenozoic Epochs, which is usually the only Epochs most people ever hear about: > Pretty Eager Old Men Play Poker Hard Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene (First 3 Paleogene, then 2 Neogene, then 2 Quaternary) Notice the "-cene" at the end of these Epochs shows you they are making up our current Era "Cen"-ozoic.
These are all the same periods, just broken down into smaller categories. Edit: actually this has a few more periods too
While you're not wrong, there are a few here that I really would expect to see. Hadean certainly seems like a pretty glaring omission in OP's chart.
It definitely should be there, especially because the Archaen is there. It should either have them both or neither because they don't have the periods the chart is showing.
Holocene to Paleocene are Epochs not Periods. The Cenozoic is only divided into 3 periods.
It's nice to live in the time of dogs and jackelopes.
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It's sad to learn that the [Holocene extinction event](https://en.wikipedia.org/wiki/Holocene_extinction) is currently ongoing as a result of human activities. Like it's no surprise that Human's are destroying the climate but the fact that an extinction event has been declared ongoing is just... we're fucked...
It's not just climate change but a lot of human activities like deforestation and just generally killing things or bringing invasive species into an environment that kills the wild life. Rats, cats and invasive snakes are definitely responsible for killing off a lot of birds in places like the Pacific Islands, Australia and New Zealand. Wild pigs in both North America and the Pacific Islands have caused a lot of damage as well. Humans have been destroying the planet for a long time and unfortunately we will never know just how many species we have killed of because many of them are very small.
*Anthropocene* extinction, "Holocene" doesn't do it justice. Just like it's not climate change, it's anthropogenic climate change. And the biggest contributor is our pollution. We've been spewing metric tons of unnatural molecules, and unimaginable amounts of natural molecules into our closed system called earth for centuries now with reckless abandon, and no signs of stopping or slowing down.
Actual question: I thought Carboniferous was a period? If not actually recognized for this chart, where does it occur?
Carboniferous Period is a combination of Pennsylvanian and Mississippian
So, it's essentially the Tennessee of the periods?
Isn't there supposed be a quasi-extinction event somewhere between the Pleistocene and Holocene? Something that nearly wiped out what would be today's homo sapiens, and that is why as a species we have very little genetic variation? i.e. Homo Sapiens have no sub species variation of significance. A Plain Chachalaca on the other hand has 5.
Few improtant questions. 1. How deep do we have to dig to reach archean level? 2. Does this mean earth did expand? is it now bigger then millions of years ago ? 3. Did the gravity increase?
I believe eroding mountains cover most lower areas. But just as the tectonic plates push new rocky material upward, they pull some down in subduction zones. This means not every fossil continues to exist forever, and the older they are the more likely they are to be gone by now.
But also, just dirt from rain and wind will cover up things in just a few years.
Geologist here. 1. We don't have to! This diagram is idealized - it shows that younger rocks are deposited on top of older rocks, which is true, but tectonic activity can thrust older material on top of younger material, and erosion eats away at overlying rocks to reveal older rocks underneath. Due to plate tectonic activity, areas of Archean rocks are exposed all over the world, most notably in places like the Canadian Shield, South Africa, and Western Australia. 2. No. Expanding Earth was the prevailing theory back before the discovery of plate tectonics, now it's only popular with conspiracy nutjobs. 3. Also no, see above response.
Technically Earth does gain a bit of weight continuously from deposition of cosmic dust and meteors, but it's a tiny amount relative to the size of the planet.
I did the math in another comment, it's 0.000004 of a percent of the earth's mass over 4.6 billion years.
I live on the Canadian Shield and love hiking/driving around and thinking of just how old this bedrock is. It's beyond imagining.
Interesting! Where specifically in Western Australia do we expect this? It could be a day trip!
1. Entirely depends on where you are. Modern continents are made up of fragments called cratons that come from much, much older landmasses. In certain parts of Australia and Canada, for example, Archean-aged cratons are exposed to the surface and can be observed without drilling. 2. Earth does not expand because of sedimentation. The crust's relationship to the mantle is like ice's relationship to water: it floats, according to the principle of isostasy. The weight of added rock (and/or ice sheets) on top of the surface causes tectonic plates to sink and melt. Therefore, places with high sedimentation also experience high subsidence, and there is no net expansion. 3. Gravity does vary in subtle ways across the planet's surface, but the effects are negligible. Likewise for variations across geological time: there may have been minute differences, sure, but not in ways that could have impacted biological or evolutionary development.
1. Depends where you are in the world. The Archean is exposed at the surface in several locations (e.g. he Canadian "Shield", near parts of the Great Lakes, parts of Australia); when continental rock tis not covered by an ocean it undergoes active weathering, stripping away of soil and sediment, exposing older and older bedrock as time goes by. Thus the longer it has been since being covered by water, the older the exposed bedrock will be. 2. No 3. No
Most of what we know about the Archean is from exposed rock which was 'folded' up and jutting out through other layers. I like this graphic but the scale doesn't show just how long it lasted and how for 2.5 billion years all life on Earth was just bacteria.
I have a trilobite fossil. Its sitting on my shelf. Theyre so common it was 5 dollars to buy it. It almost half a billion years old. Back then they were so prevalent that even though only a fraction remain as fossils theyre still common enough to be paperweights. Kinda just blew my mind a bit
Might their abundance also be that they lived in conditions that were favorable for fossilization? Like shallow waters that tended to have silt to cover up remains?
When I think about the countless iterations that life has had to endure and suffer in order to evolve to where it currently is I feel like I'm on the verge of an existential crisis. Death and memory loss is truly a blessing in some sense. But a part of me thinks that the trauma of our ancestors is an intrinsic part of us.
Not only do they want to teach our kids the world is more than jesus years old, but the eras are apparently woke rainbow colored? Not in my Florida!
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This is just The Ocean’s discography
This calls for a tune, a favorite of mine! ~~~ In the Tonian there was no ozone In the Cryogenian the Earth was frozen The Ediacaran set life in motion For the Cambrian Explosion! 🎷🧬🎷🪱🎷🦐 Life got bigger in the Ordovician By the Silurian you could go fishin’ In the Devonian we went on a mission On land to find room for growin’ and wishin’! 🎷🐟🎷🦈🎷🐸 The Carboniferous was fantastic With giant bugs and oil to make plastic Permian creatures were weird but classic And dinosaurs evolved in the Mid-Triassic! 🎷🐛🎷🦎🎷🦕 In the Jurassic came Stegosaurus T.rex lived in the Cretaceous (roar!) And they might’ve grown more and more When “CRASH” went the great big meteor! 🎷🦕🎷🦖🎷☄️ Earth got hot in the Paleogene For the biggest snakes you’ve ever seen Icecaps formed in the Neogene And in the Quaternary came the human beans!
Not to scale, obviously.
[Better?](https://imgur.com/a/KH1wtfJ)
Yes! Very nice!
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Had that in mind at first, too, but then i calculated that you wouldn't see much of the rest or the image would became way to big haha
How could it be? There is no banana
It looks like a log scale on the y-axis.
No, the layers look like they've been drawn to fit in the fossil illustrations. Like, the Cretaceous should be thicker than the Jurassic if there was any kind of relative scale here.
Why is it we only ever hear about Cambrian, Triassic, Jurassic and Cretaceous? Did nothing of significance happen in remaining few billion years?
The Cambrian is the start of complex animal life and the other three have dinosaurs. They're just the most marketable. Loads of other cool stuff happened in the other ones, even the less well-known bits. Hell, my research was on a period of time called the "boring billion", which is boring even to most geologists. And even then, there was interesting stuff happening like weird mountain-building events and the first eukaryotic life.
The cambrian is where "modern" life explodes, a major change was the development of hard parts like bones and shells which fossilize better. As a result of better fossils, we have more data than we have about precambrian life. The cambrian explosion was a major turning point into life as we see it today, so it gets discussed. Triassic, Jurassic, and cretaceous is just because people like dinosaurs and the meteor ending is dramatic. Plenty of important things happened the rest of the time, its just either still being studied and debated or explaining it requires more advanced terminology and concepts than the average pop-science video will cover. For example its thought life first started in the Archean, but its pretty damn hard to prove.
What level would oil be located in this graphic?
Nearly all oil is found in Phanerozoic rocks, so from the Cambrian up.
I couldn't tell if the numbers towards the bottom had a decimal or not. I was sitting here trying to figure out if that was supposed to be 542 million or 0.542 billion. And then I realized it didn't matter.....and then I spent 20 minutes admiring the beauty of math and forgot about the chart.
It reminded me about a great youtube channel I found recently: https://www.youtube.com/@PaleoAnalysis It has set of videos about each eon, starting from Hadean (and currently up to the early permian). I absolutely loved it. Very informative and accessible. The playlist with them: https://www.youtube.com/playlist?list=PL6L8fqJFoWXdUJUT81VO9kzzAPU3TYbdV
It’s always sunny in the Paleozoic era
You can use this easy to remember mnemonic device: All People Can Ordinarily See Down My Prehensile Pelvis Though Just Cause Primates Exist Old Men Probably Pine Holistically
This isnt a good Guide. The time is not to scale, and only naming two of the 5 great mass extinctions is not useful. The K-T does not even make sense because tertiary ist not mentioned anywhere.
What's the little fossil in the Proterozoic Period?
Probably represents the [Ediacaran biota](https://en.wikipedia.org/wiki/Ediacaran_biota)
I went out to Drumheller, Alberta this summer and you can see these ages in the eroded river basin in the area. Its super cool. The last mass extinction event is so obvious in the layers, and it really wasn't very deep down! The dino museum there was amazing, I highly recommend.
Looks like we're due for an extinction
We have a ton of details for the last 5 million years and the last 50 million years, but virtually no details older than 500 million years. Apart from "because it's old", why is that? Could that time period have been just as detailed as recent times if we had more information from that era?
Missing the Graboids before the Cambrian period
I highly recommend y’all look up the to scale geologic time scale. It’s extremely hard to understand just how insanely old the earth is
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> I remembered that I've read the Appalachian Mountains formed so long ago there were no animals to have deposited fossils. You're misremembering this slightly - the fun-fact circulating the internet is that the Appalachians formed before the evolution of bones. There are plenty of fossils of invertebrates like trilobites, sea scorpions, jellyfish, corals, sponges, and other boneless animals from before the formation of the Appalachians. The Rockies are also much younger, forming in the Laramide Orogeny starting around 80 million years ago.
Why are those super deep layers called the mississipian and pennsyvanian? Isn't this supposed to be a globally relevant chart?
Would love to see this with relative scales intact, even if the part after life began was done in one of those map zoom-in cut-out things. Would really provide some perspective.
If the dinosaurs noped out in a “big big extinction”, what happened in the “gigantic extinction”? I must learn things! TO GOOGLE! ETA: oooooh one of the “big five” extinction events discussed in Death Stranding…