Incoming: The Chicxulub Impactor, Part 4 ― The Timeline By Stephanie Osborn

Incoming: The Chicxulub Impactor, Part 4 ― The Timeline

By Stephanie Osborn

In order to best


In order to best understand the details of what happened, along with the speed with which they occurred, I thought it made sense to generate a rough timeline of events. With considerable research, judicious estimations, and a bit of calculation, I was able to put together a table that depicts how events would have happened across North America. I lay NO claim to its preciseness; without knowing a great deal more detail than it is currently possible to know, there are a lot of things I just can’t determine.

Note that the primary distance used roughly corresponds with New Orleans, Louisiana, USA (aka NOLA); this is approximately the distance from the tip of the Yucatan Peninsula to the northern coast of the Gulf of Mexico. Also note that, by some researchers’ estimates, no living thing within this radius would have survived the initial impact.


Time from Impact


0/000/00:00:00 Impact. The asteroid blasts a crater possibly up to 30mi deep.
0/000/00:00:05 The central peak rebounds, temporarily forming a mountain higher than Everest.
0/000/00:00:09 Thermal radiation blast; plants spontaneously combust, animals suffer instant 3rd-6th degree burns at NOLA; all life within that radius dies instantly.
0/000/00:03:00 The central peak collapses, flooding the crater with lava, which splashes and rebounds from the periphery. The lava splash forms a ring of tall peaks as it solidifies.
0/000/00:04:10 Magnitude 10+ earthquake strikes NOLA as the P wave arrives.
0/000/00:04:20 Seismic seiches begin to set up in inland waters.
0/000/00:05:33 The S wave of quake strikes at NOLA.
0/000/00:08:00 Molten ejecta (7500km/hr, 4660mph) begins to fall at NOLA; secondary fires ignite anything that was not burned in the thermal blast; the atmosphere heats back up. An atmospheric shock wave hits NOLA?
0/000/00:08:20 The Love & Rayleigh surface waves strike NOLA (total quake duration:  ~5-6min minimum).
0/000/00:09:00 The atmosphere begins to dim to complete darkness from the combination of rock ash and smoke from fires
0/000/00:20:00 Sea water resurges into the crater, over the peak ring, carrying ~130ft (40m) of impactite debris and depositing it across the crater.
0/000/01:00:00 The peak ring is breached to the northeast by resurge, and another ~33ft (10m) of impactite is deposited; this layer is more rounded and size-graded (sorted), indicating it has traveled further through turbulent flow.
0/000/01:10:00 First megatsunami strikes NOLA.
0/000/01:40:00 Ejecta could reach the opposite side of Earth. Fires may ignite world-wide.
0/000/02:00:00 Ejecta ceases falling at NOLA.
0/000/02:30:00 Secondary mega-tsunamis (from underwater landslides) begin to  strike NOLA.
0/000/03:00:00 The sky gradually lightens to twilight levels; Earth starts to enter a “nuclear winter.” Scientists estimate that the “nuclear winter” effect dropped global temperatures by as much as 30°F (~17°C), for anywhere from a year to decades.
0/000/05:00:00 Acid rain begins to fall at NOLA.
0/000/06:00:00 Smallest animals begin to suffer silicosis from ash inhalation, far away from the impact site.
0/007/00:00:00 The first animals begin to die of secondary effects (silicosis, injury).
0/040/00:00:00 The first animals begin to die of starvation.
1-50/000/00:00:00 “Nuclear winter” ends. The atmosphere begins to clear; temperatures begin to warm toward the Paleocene-Eocene Thermal Maximum.
200,000/000/00:00:00 Temperatures begin to cool from the Paleocene-Eocene Thermal Maximum.



For more details, check out INCOMING! The Chicxulub Impactor by Stephanie Osborn on Kindle and Nook.


And check out Stephanie’s fiction, also!



153 thoughts on “Incoming: The Chicxulub Impactor, Part 4 ― The Timeline By Stephanie Osborn

  1. In order to best understand the details of what happened, along with the speed with which they occurred, I thought it made sense to generate a rough timeline of events. With considerable research, judicious estimations, and a bit of calculation, I was able to put together a table that depicts how events would have happened across North America. I lay NO claim to its preciseness; without knowing a great deal more detail than it is currently possible to know, there are a lot of things I just can’t determine.

    K, I love this so much.

    “Look, here’s a reasonable understanding of what happened. Because of a lack of a lot of needed details, it’s probably not exactly what happened. But it’s consistent with what we know, and the assumptions are the best I can come up with so you get an accurate IDEA.”

      1. *HUGE BLUSH*
        Thank y’all, so much! I appreciate that more than you know. I did work hard on this book/presentation/blog series, and looked up as many details as I could find, just so I could do this particular timeline.

        In particular, I worked on the arrival times of the various waves — quake, tsunami, etc., calculating most of them myself. The problem there is that 1) the various quake waves do not all have the same speed, traveling along very different pathways (e.g. body waves tend to travel much faster than surface waves). And 2) all of ’em, including the tsunami waves, tend to have a RANGE of velocities.

        In the case of the quake waves, this is because the speed is partly dependent on the density of the medium in which it travels — meaning that each rock stratum forces it to change speeds. Worse, each stratum boundary causes what you could think of as optical effects — reflection and refraction, and this also involves changes in the polarization of the reflected waves (transverse, longitudinal, elliptical). It is partly this effect that tends to increase the duration of each phase of a quake, as the various original waves arrive in a wave train, accompanied by the “packets” produced by all that reflection.

        So what I tried to do was to judiciously estimate a reasonable average speed for each wave type from within the range associated with each. In the case of the primary megatsunami, I tended to go with something near the top of the range; in the case of the quake waves, I hit much nearer the middle of the ranges. Then it was a simple matter of determining the distance traveled from ground zero of the impact site to the “observing” sites. Since v=d/t, then some basic algebra yielded t=d/v, and then I just plugged and chugged.

        I’m still not 100% sure of the silicosis deaths; the data from the Ashfall Fossil Beds State Historical Park in Nebraska (resulting from one of the Yellowstone eruptions) would seem to indicate a swifter death from silicosis, but the value I used was turned up in a research paper, so I went with it.

        FYI, the timestamp format on the timeline is the same as we used to use on Shuttle missions, with the expansion of the notation for more than 99 days, plus years — which, of course, we didn’t need, when I worked the program. But it was dd/hh:mm:ss, so I went with it as being a convenient nomenclature. I was a timeline engineer for Shuttle, so this is more or less in my bailiwick.

                    1. You didn’t. Everything’s cool. I’ve just been a bit off with my memory between the pneumonia vaccine (which I finally am over) and the doctor playing games with my BP meds. (This is BP med #3. Finally found one that doesn’t cause icky side effects, but have to go on higher dosage for proper BP control. Oy. BP finally down to around 140-150/80-90, but needs to go lower, so working on it. i do have to wonder how much my other meds contribute; I know there is at least 1 that can increase BP, maybe 2.)

        1. I wondered about the Ashfall time when I first read it. My question was sample bias, and if the comparatively young average age of the critters (smaller, closer to the ground, breathing in more ash) biased the overall speed of demise.

          That also gave me nightmares, because some of the descriptions I read were just too good. *shiver*

          (If you go to Ashfall Fossil Beds, and you wear contact lenses, don’t go on a dry, windy day unless you wear other eye-protection. Trust me on this one.)

      1. We get the word History from a work that translates as Investigations.

        The observation that Clio is Muse of Detectives is a part of the insanity troubling me as a creative writing WIP.

      2. Yes. Yes, it is, pretty much. Which, I suppose, is why I’ve always loved the mystery genre in addition to science fiction. And why I tend to merge the two in my own fiction.

  2. Ummm…you’re aware the rock shown in that picture is about 900 miles across? If the meteorite was really that big, it would have rearranged the planet like Agent Franks rearranging a gnome’s face.

    The actual impactor was less than 1/1,000th of the Earth’s diameter. Planets iz BIG!!
    At my house, the ‘things that go bump in the night’ are cats.

    1. You realize that if the Chicx impactor was shown to scale that you probably wouldn’t even see it? Please review the numerous blog entries here and on MCG concerning cover art. Thank you!

      1. Yeah, showing things to scale with correct lighting… doesn’t make for good illustrations.

        -former illustrator

        1. Maybe you’ll be able to answer– one of the guys here wrote a zinger of a blogpost about Conan, and a digression ended up with this question:

          Is it just really, really hard to get chest hair that looks ‘right’?

                  1. Well, where would he shop for clothes? He’s what, about a 140 extra-extra-extra-long? Even Thornton Mellon’s Tall & Fat stores would give up in despair.
                    Susan Ivanova: “You’re saying just because I’m holding this right now, I’m Green Leader? But I’m human!”

                    Former Drazi Green Leader: “Rules of combat older than contact with other races. Did not mention aliens. Rules change…caught up in committee. Not come through yet.”

                    Susan: “Bureaucracy. Ya gotta love it.”

        2. No kidding. I’ve just spent the past 9 months learning how to do anime/comic “darkness”. And I still have plenty to learn.

          If I get it too far off “this is where the light source is” I risk the uncanny valley effect. If I’m too literal, I can’t tell the story.

      2. Exactly. Even the crater diameter, which is considerably larger than the impactor, is only about 1% the diameter of the Earth. You’re talking about a streak of light and a sudden fireball, at that distance and resolution. It would look like an ordinary meteor, not a nigh-planet-killer.

      3. Actually, it is interesting to imagine it in scale: take a basketball sized Earth (about 24 cm diameter) and thwack it with a grain of table salt (about 0.3 mm diameter). If I’ve done my math correctly, that’s about a 1/50,000,000 scale model of Chicxulub.

        Hardly seems like an impact worth noticing. But since kinetic energy is m*v**2 it scales at the fifth power…

        1. Yeah, that’s about the scale I got: beach ball, grain of sand. NOT beach ball, tennis ball! Or even ping-pong ball.

          I guess it’s one of my pet peeves, that blatantly inaccurate pseudo-scientific illustrations set my teeth on edge. Like those paintings of the asteroid belt that show a dozen lumpy gray boulders in one frame.

          In reality, if you traveled through the asteroid belt for a year you would probably never see two rocks at the same time. Usually, there wouldn’t be a rock bigger than your fist within a hundred miles.

          And the ones that depict the Oort Cloud as crowded! AAARRRGGHHH!!

          Most people are clueless about these matters, and if nothing they see is accurate, how are they ever to become less clueless?

          1. When you don’t have the cash available to fork out for a custom, accurate illustration for a blog article, you look for what’s available online, preferably in the public domain, though for a blog article (as opposed to a book for sale), public domain can be squishy. Unfortunately those are largely going to be inaccurate.

            Yes, my husband is a graphics artist. But he spends most of his time on paying gigs, and I try not to bother him too much because also serious heart patient, and I don’t want to stress him too much.

            1. Space, the Empty Frontier. These are the voyages of the Starship, Enterprise. It’s five year mission, to travel from one lonely isolated rock to another, while trying to detect that one hydrogen atom per cubic kilometer of space.

        2. Not only that, but my understanding via Travis Taylor is that if it’s moving at a fairly low percentage of lightspeed (3%? 5%?) Newtonian starts yielding to Einsteinian physics for that energy release. When mc squared is involved, E starts adding up FAST.

        1. Tryanos love them some Leidenheimer’s. Cheeseburger poboys all the way (My second choice after shrimp . . . I can taste one, right now)

          (amazingly I got the spelling right on them first guess. Musta sunk in after 20 years of living there)

      1. What No Bronto Burgers? Although in NOLA a Triceratops PoBoy (followed by a few dozen Beignet) might be more typical :-). Though how they’d get the beignet to their mouths with the little arms is an issue…

            1. I did some quick digging and the fossil record for Rubiaceae stops at the Eocene. And it’s not the subfamily that contains Coffea whose caffeine producing qualities are (supposedly) even more recent.

              Sorry T-rex!

              1. Right no coffee before the Eocene, Gonna have to bring it with us on the Stegasaurus hunt next weekend…

        1. to quote Debby Harry:
          “You go out at night, eatin’ cars
          You eat Cadillacs, Lincolns too
          Mercury’s and Subaru’s
          And you don’t stop, you keep on eatin’ cars
          Then, when there’s no more cars
          You go out at night and eat up bars where the people meet
          Face to face, dance cheek to cheek”

    2. There’s this wonderful little phrase that people used to use a lot, that would seem to fit in right here: “Artist’s conception of…”

      The pictures (already used here) are so different that probably *one* of them at most could be, uh, photo-realistic. And “none” seems to be about the “right” answer, see above.

      And yet every one of them (at least to me) gets across the sheer, let me just say ‘awesomeness’ of it (in the original meaning, as in ‘awe’).

      1. There’s this wonderful little phrase that people used to use a lot, that would seem to fit in right here: “Artist’s conception of…”

        More like “Artist’s misconception of…”

        I know, I know, I’m being a pain. Grumble grumble grumble…

        It would be cool to see an animation of how it really went down. A hair-fine streak of brilliant white light appears, gets longer, longer, and five to ten seconds later ends in a slowly growing ball of even brighter light that reaches well beyond the thin layer of atmosphere. After half a minute it begins dimming to bright yellow, still expanding…two or three minutes to get down to dull red and start breaking up.

        Everything close to the incoming object’s path would get fried to crispy crunchy too.

        1. Except I strongly suspect that your initial timeline is much too long, and your end timeline is much too short. At the estimated incoming velocity, it would have taken less than 45 seconds for the asteroid to traverse the entire depth of Earth’s atmosphere. With a KE at impact of over 100,000 GIGAtons equivalent, and generating a temperature estimated as high as ~10,000K, I expect it will take a lot longer than two or three minutes to dim to a dull red, let alone break up.

          I suggest going back and studying the Shoemaker-Levy 9 cometary impacts on Jupiter. Those are probably closer in approximation.

          So basically what we have is something so incredible, so extreme, that human minds can barely grasp it in any case.

          FWIW, I didn’t put any illustrations into the ebook, partly because of that issue. But blog articles tend to scream for some sort of illustration, so I did the best with what I had to work with..

          1. Well, depending on velocity and angle I get a range of 5 to 25 seconds from first glow to impact. It couldn’t have come in at an extremely shallow angle, or it really would have dug a trench. I’d say, no lower than 10 degrees.

            If the fireball expanded for three minutes it could get over 200 KM in radius. How long would it grow, how big could it get? I didn’t want to go too far overboard.

            Hmmm. The fireball would be largely composed of vaporized rock, wouldn’t it? What’s the speed of sound in a compressed rock gas medium?

            1. The primary part of the atmosphere is less than 500km thick. The incoming asteroid is estimated to have been moving at a speed of just shy of 13km/s. Travel time for a mostly vertical trajectory would be shy of 40s.

              Current MINIMUM size for the crater is a bit under 200km diameter. There is evidence to indicate it reached 300km or better in diameter and went as deep as 20-50km.

              I’m not that worried about Mach in a particular medium; at these energies, standard everyday considerations of compressibility of material pretty much defenestrates.

              1. Nuts. My reply to this went to the wrong place.

                I never disagreed; the rock zipped through the atmosphere in a few seconds.

                  1. Well, 150 KM of atmosphere, 13 KPS velocity, I get just over 11 seconds.

                    Or are you saying the significant part of the atmosphere is 500 METERS deep?

                    1. You know what? You’re probably right. I need to stop doing maths when I’m feeling this lousy. I thought I could at least do basic arithmetic but this vaccination nailed me harder than I’d realized.

                    2. Yuck. Which vaccine is it? Pneumonia, Shingles? Probably doesn’t matter since I’ll probably need both next time I go in for my annual.

                      Hmm. Now I’m going to have to reread your Div One series so I can remind myself how many vaccinations Meg had to have.

                    3. It was the pneumonia vaccine. I can’t get my hands on the shingles vaccine, and I’ve already had the flu vaccine. The flu vaccine made me feel a little under the weather, but I just now got dressed (it’s 4:30pm my time) for the first time since Wednesday. Still not feeling great today, but a little better than yesterday. Fortunately I have a few days here where I don’t have to be anywhere, so I took the opportunity to grab the vaccinations. I’d thought I was going to get pneumonia AND shingles, but I think I’m glad, now, that they didn’t have the shingles.

                      That in itself is stupid-ridiculous. The pharmacy’s wait list was 80 people long, and they only get enough vaccine to do 5 people per QUARTER. It will be literal YEARS before they reach me. So I’m trying to find another way to get it…though not until I feel better from the pneumonia one!

                      I. Have. Felt. CRUMMY. Feverish, achy, headachy, appetite way off, moderate head/chest congestion, shoulder too sore to hardly touch. I haven’t felt that bad since the nastybad flu actually gave me pneumonia in Jan 2018. I AM better today, though I’m still achy, headachy, congested, and my appetite is off. So I’m not gonna try to really answer many questions today; I learned my lesson.

                      Anyway, sorry I’ve been “off” for the answers to questions and whatnot, this go. I guess I was dropping some decimals someplace. I’ll try to do better next time — I should be feeling much better next week! (Heck, I’m having to cut and paste all over in this comment, just to get the flow to make decent sense.)

                    4. My doctor’s office has not had the shingle vaccine in over nine months, but the last visit, he suggested trying the pharmacy. They did have it.

                      Additional note: they warned at the time that it’s a painful one. It was as bad as the time I got a flu vaccine and sleep on the injection site.

  3. I’d be interested to read some detailed analysis and theories as to why certain animals survived the nuclear winter (and other horrors) while many did not. Why did alligators survive but not swamp-dwelling dinosaurs? The same with relatively small mammals but not small dinosaurs.

    1. I will hazard a GUESS that small and mobile (follow the heat, food, breathable air…) was an advantage, as was the ability to self-generate heat. Not a guarantee, but an advantage. Perhaps anything hibernation-capable also had an advantage.

    2. Crocodilians have an ability to go into a stupor in cold environments that can last months or possibly a year (depending on how well fed they were).

      Look for pics and videos online of gators in the Carolinas and other areas where freezes occur, where the water surface is frozen thick enough to walk on, but there are gator noses sticking out of the ice, to meet the very low respiration needs in that state. They’d just have to survive until the temps dropped to that level (by which time a lot of the ashfall would be over, so their nostrils wouldn’t get clogged).

  4. Would the radiant thermal flash immediately affect areas at 1,000 km distance (i.e. NOLA)? Because Earth curvature means line-of-sight is about 80km up. There would some effect from re-radiation from atmosphere heated by the flash above the horizon at NOLA, but would that torch everything? Also, what causes the 9 second delay betweem impact and thermal blast at at 1,000 km? Time for for the superhot gas from the impact to climb above the horizon?

    There would be a wave of superheated gas, but that would arrive at speed of sound, I think; about 50 minutes after to 1,000 km..

    1. Had wondered the same thing. Radiant energy is speed of light. Treating NOLA as 600 miles from Chicxulub that yields about 3 milliseconds. But of course NOLA is over the horizon So it can’t be direct. Obviously I’m missing something here. Radiation from the fireball? Certainly the fireball is going to go right up through the Stratosphere so once it gets up line of sight issue goes away.

      1. Well, if it was radio waves, then I could understand them being reflected off the atmosphere back to the surface. e.g. over the horizon backscatter radar.

        1. I think far infrared and microwave are right up against each other. I forget how black body radiation works. Perhaps at some temperatures microwaves are emitted? No, wait, doesn’t it move the other direction?

          Do we really know enough about the atmosphere and about the fluid mechanics of such conditions to be 100% on speed and mechanisms of energy transfer?

          1. Not really, no. (Fluid mechanics, probably. Atmosphere, not so much.)
            In this case, that wasn’t a calculation of mine; the info was pulled from many papers and reference materials. So I’m not 100% sure how they got that distance. But yes, the fireball is gonna go up, and go up pretty fast, so line of sight is gonna occur very fast.

            Shock waves from things like this tend to transcend Mach, believe it or not; even the pyroclastic blast from Mt. St. Helens briefly exceeded Mach, and that was a fairly ordinary volcanic eruption as such things go.

            1. Right air is usually treated as an uncompressible fluid and so we expect Mach to be the limit. But I’m pretty sure the shockwaves from nuclear explosions compress stuff to break Mach and this thing is going to make the 50 Megaton Tsar bomb look like a cap gun. On top of that the heat near the blast is going to be so immense that the gasses probably are pushing into plasma. Conditions so weird that pretty much all bets are off.

              1. I know I don’t know much about the fluid mechanics of shock.

                Nukes, this, and hypersonics look like they might have some interesting differences from flow at STP.

              2. IIRC that’s called the Mach Stem where the two shock waves caused by a nuke (primary and reflected from the ground) merge as the (faster) reflected shock wave catches up with the primary. It’s been years (decades) since I did these kind of calculations (or had access to correct (classified) info tables), so my explanation may be off.

                The main reason I remember any of this is a fellow targeting officer loved to use a fake German accent and yell MACH STEM! when discussing this during planning or training.

          2. From what I remember, black body radiation at the microwave frequencies entails absurdly low temps, like 3 Kelvin. (Going from memory from a NOVA program where NASA had a U2 looking at Big Bang radiation.) I think I have the relevant text books, but they’re not handy, and it’s been a strenuous day.

            Protip: if you retire to the country, don’t be surprised if you are doing a hell of a lot more physical labor than when you were citified. 🙂

            1. Stars are nigh-perfect blackbody radiators, so I can show you that pretty readily. The Sun’s photosphere is about 6000K, and its peak wavelength is in the yellow-green part of the visible spectrum. An M class star has a photosphere less than 3500K, and peaks in the red to near-infrared. IR is a substantial wavelength band, followed by microwave, then radio, all of which are relatively large spectral bands. (Visible light is the merest sliver of the spectrum.) And yes, the cosmic microwave background radiation equates to a temperature of about 3K. (Really only a bit above 2.7K, actually.)

              1. I’m amazed I recalled that correctly. (If memory serves, I saw the show in the 70s.) I haven’t needed to correlate black body temperature to peak wavelength in 45 years, so it was a bit of a SWAG. Thanks.

                Fantastic articles, by the way. My Kindle is saying “feed me”, and a T-Rex eating a hamburger is next up, I think. The Impactor makes the Mount Mazama dustup quite tiny in comparison, though we got a nice lake out of the deal. 🙂

                1. I’ve been to Mazama. It’s beautiful. And scary. Been to St. Helens too, and quite a few other volcanoes in the PacNW.

                  But yes, this would even make a Yellowstone supereruption pale by comparison. (Yes, that bad.)

                  1. *grew up near Mazama in Washington*

                    Mazama, scary? Skiers are obnoxious, but….


                    Crater Lake is where Mount Mazama *was*.

                    OK, yeah, that’s scary.

                    (Mom’s family is near Crater Lake, so I know it, too.)

  5. There were several events in succession and survivors needed to get past all of them.

    1. The first hours following the impact. Heat flash, quakes, air blast, tsunamis.
    2. Huge fires, possibly worldwide, lit by the heat of re-entering ejecta. Possibly lasting weeks, until everything combustible was gone.
    3. Subsequent cooling due to dust blocking sunlight.
    4. Longer-term climate effects after the dust settles. I’m not sure if this was an extended cold period or geenhouse conditions. Possibly one followed by the other. It depends on what was vaporized in the impact and remained in the atmosphere longer.

    Survivor characteristics:
    -small size
    -probably burrowing animals or cave dwellers on land, or small enough to hide beneath something to protect them (a fallen multi-ton dino perhaps?).
    -carnivores, carrion eaters, and omnivores due to loss of vegetation.

    What about reproduction and gestation periods? Small animals can reproduce quickly, was that a survival factor? What about live birth vs. egg-layers?

    1. Anything that could feed on cockroaches was guaranteed to survive. Those damn bugs have been around for over 320 million years; and survived several extinction events.

      1. Now that you mention it, I don’t recall encountering anything in my research that indicated fungi as part of the extinction. That might not mean anything except that I didn’t encounter it, though.

    2. There are research papers out there now that are being heavily debated, that indicate that the ejecta heated the air up to near-oven temps, at least in areas in the same hemisphere with the impact, and that this exacerbated the fires. I’m not sure what I think about that; I need to get my hands on the actual papers and study them, and I haven’t had enough time to dig that deep. (Which is one reason why I didn’t include it in the book/presentation/blog articles.)

  6. 0/000/00:00:05 The central peak rebounds, temporarily forming a mountain higher than Everest.
    That much mass can move that fast?
    I think rounding will work here, since the central part smashed in, let’s say 10km “bounce”. That’s 2km/sec. Sticking with rounding, the Intertubes say sea-level speed of sound is 1200km/h, which is 0.3km/sec. There is (semi?) molten pile of rock growing at mach 6?!?

    1. Again, this was information derived from papers in the course of my research. But it was a gigantic splash, and given the structures found in most impact sites, well…

    2. Maybe the key words here are “rebound” and “supersonic” both.

      The ‘slowest’ the object can come in is escape velocity (unless it hits from a closed orbit, which is even more, uh, far-fetched), and that’s about Mach 35 in air (knew that since the Apollo days) and still at least several times the speed of sound even in water or rock.

      Which means the rock (incoming and already-there both) has to travel a lot faster than the speed of sound *in rock* just to ‘get out of the way’ as it tries to occupy the same space, twice over, at miles per second. And if it *cannot* move to get out of the way, it has to be compressed, like a spring or the air in a bicycle pump, but *as a solid*, and not likely by just a little bit.

      And though I’ve been trying for at least a week to visualize that, it’s still such an extreme situation that the only thing I can compare it to is the uranium or plutonium core of an ‘implosion’ type nuclear explosive — which typically (so says the ‘open literature’ stuff I’ve read, for interest and because a character is the engineer of an “Orion” / “Ulam drive” spaceship) ends up compressed to 2 or 3 times its original density, and it’s *solid metal*.

      So, I can actually believe (absent anything more specific) that the rock can, over seconds, rebound much like the surface of a puddle of water ‘craters’ and then ‘rebounds’ when a falling raindrop hits it… though of course raindrops (at least on Earth) are nowhere near supersonic in air or water either one.

      (Wow, still wow, and probably always so. “Sense of wonder” sure enough, but here also with a real vengeance.)

      1. Thank you. That’s actually a very good explanation of what I’ve seen in the various simulations and models and whatnot.

        Y’all, please excuse me on my explanations (or lack thereof, as the case may be) today. My doctor wanted me to take the latest pneumonia vaccine (because I have a predilection for it), so I grabbed the opportunity yesterday as being between anything I had to go attend, and it is whupping my @$$ big-time today. I got styrofoam peanuts for brains today. Or maybe polenta.

        I haven’t felt this bad since that nastybad influenza GAVE me pneumonia back in January 2018. I mean, that’s good, it means the thing is working and kicking my immune system into high gear, but yeesh. I haven’t gotten out of my jammies an’ winter bootie houseshoes all day today, and that’s way unusual for me. My shoulder is still hot and still painful — I couldn’t sleep on my right side hardly at all last night, and I mostly sleep curled on my right side, so I didn’t sleep great — that side of my neck is even stiff, and I feel vaguely feverish and tired.

        I think I’m glad nobody had the shingles vaccine, which I’m also supposed to take…

        Anyway, hopefully I’ll do better for y’all next week.

        1. If it’s the new improved pneumonia vaccine, it has a hell of a kick. Got mine 3 days before an unrelated med appointment, and thought I caught the flu by then. 102F fever that night, and spent most of the evening in the urgent care center nearest my hotel. Chest X-rays led them to believe it could have been pneumonia, so I got to find a handy pharmacy. Not the flu (from culture tests), and not pneumonia, but sheesh.

          Felt human a couple days later. At my age, I don’t need another booster. Yay! I normally tolerate vaccines well (waggles hand), but when I don’t, it’s interesting.

          1. Aye. MOST vaccinations my reaction consists of, “Is that soreness from exertion or injection or vaccine action?” and “Oh, right, THAT’S what that is. Time for the injection sight bandage to come off.”

            Looks like I have another ‘fun’ time to look forward to… when the pneumo stuff gets recommended (or I decide to just go for it and be done).

            1. I had the older style vaccine some years ago, with little effect. Got the booster 18 months early, and it was the new style. Yow!

              I got the shingles vaccine in 2013, and passed on the New! Improved! booster. IIRC, out of pocket costs were going to be high, circa March 2018.

              I’m also a bit skeptical about New! Improved! vaccines. $SPOUSE tells me the pneumonia vax adverts now say 5-10% of the people who get it have adverse reactions. Yep.

              1. Aaaaaand, the older you are, the more likely the new vaccine are likely to kick your butt; which I will extrapolate to add, the more vulnerable you are …. Based on tales I’ve heard.

                1. I keep thinking of the fellow who got the smallpox vaccine (back when) and was worried he was coming down with the actual disease… came back to see the doc.. who looked him over and said, “Good take!”

                    1. Oh, freakin’ lovely. I’ll have to schedule it at the beginning of a whole MONTH where I got nothin’ going. Assuming I can FIND any.
                      Well, it’s good info, I guess. Thanks.

  7. The primary part of the atmosphere is less than 500km thick.

    A lot less. According to a chart I just looked up, air pressure at 150 KM is about 5 millionths of a millibar. That’s a slightly gassy vacuum, and no impediment at all to a two-trillion-ton rock.

    Is that right? Two million million tons? Crikey!

    Why do you keep hammering on this point? We both agree, the rock zipped through the atmosphere in a few seconds.

        1. Which, in turn, makes me think of Dr. David Johnston, the guy who made the final call, “Vancouver! Vancouver! This is it! This is it!” when St. Helens blew.
          When I visited St. Helens some years back, it turns out that the generally aired recording of that call was edited. The full call went, “Vancouver! Vancouver! This is it! This is it! This is… it…” and you realize that he’s just understood he’s about to die. According to the ranger with whom I discussed the call, the carrier signal lasted MAYBE another 12-15 sec after the call. And he was nearly 4.5 miles from what is now the caldera, on the first ridge north of the volcano.
          That ridge, which had been heavily forested, is now bare rock. There are a few twisted, broken tree stumps here and there, but the foliage is so much splintery sawdust on the north side of the ridge, and the pyroclastic flow even scoured away the soil down to (and including part of) the bedrock.
          I wonder, sometimes, what Johnston did next. Did he try to flee? Did he turn his back? Did he simply stand there and watch his death roaring toward him? I’m not sure I want to know what went through his mind in his final moments.

          1. Drat. I had inserted a “voice breaks” in the ellipsis in that last “this is it,” and WordPress ate it. Because his voice obviously did break with emotion.

            1. Not to mention some of the others who were supposedly outside of the “red zone” and barely survived. Others also outside the “red zone”, but didn’t survive. None of whom knew what was coming.

              1. Yes. It’s really kind of interesting, and shows you how recent is some of our scientific knowledge: the reason they were all caught so off-guard was because, up until that time (and remember, it erupted in 1980), nobody knew that volcanoes COULD erupt any other way but straight up. It apparently never occurred to them that the side could blow out.

                1. Yes. OTOH had they known, what would have the red zone been? Could they evacuate out that much area? I mean it wasn’t the blast that took out the Weyerhaeuser Yard, but the mud flow … Ditto the camper’s on the Tuttle. Shut down I-5 long term?

                  We were in Longview, WA at the time. The mud flow did get all the way down the Tuttle to the Columbia. Castle Rock had river overflow, but neither Longview or Kelso did, or minimal. Columbia had to be dredged. But, getting off my point.

                  Part of Longview we had our rental was the area that has levees and canals. House backed up against a canal. With a wet area across the street (not developed yet). We were a tad worried about the new “dam”. OTOH we weren’t still on on Rainer, with all the black out ash, where we’d been the day before. We ended up buying on the hill, didn’t even look on the flat lands.

                2. nobody knew that volcanoes COULD erupt any other way but straight up.

                  In fairness, all the papier-mâché models showed them exploding that way. The science was thoroughly settled.

                  1. The notify box and I seem to have a slight disagreement: I say I ticked it, it says I ticked it not.

                    This time I’m making sure it is good and ticked.

      1. 900ish? but i also made a bunch of backstory notes, some of which wasted a bit of time looking for known systems before i figured it was a waste….

          1. originally i was trying to not have pages of notes, because sometimes i burn my enthusiasm for a story by spending large numbers of words fiddling with the world, but i needed to be able to keep things like planet names and character names consistent.

    1. Almost 300 and fell asleep listening to my husband DMing.

      Almost smacked him, trying to catch the “baby” that was “falling off” my belly when he picked up my laptop so he could get to bed. 😆

  8. Stephanie, I think you have an error in the later part of your timeline. You have 40 days before the first animals start to die of starvation. Small mammals — and in the Late Cretaceous there weren’t any other kinds – can’t go 40 days without eating. Most of them can’t last 5 days without eating; the very smallest ones, shrews and voles and mice and such, can’t last a single day without eating. Birds are even worse off. I don’t think you can get away with saying they ate carrion either — too many small animals and birds are insectivores or herbivores. They need live insects or leaves or stems, or at least reasonably fresh dead stuff, every day. I give it a maximum of 7 days after impact before you start to see wide-scale starvation, and probably less.

    1. There was probably enough carrion for small meat eaters, and possibly enough vegetation for the small plant eaters to subsist on. New growth? Not so much. I suspect that’s what her sources based their estimates on.

  9. That seems like an iffy explanation to me. Pretty much any predator will take carrion whenever it can – high return for low energy expense — but after a few days, carrion is so rotten that only a true scavenger, with a scavenger’s ironclad digestive system, can eat it and not get sick.

    1. No herbivores, and no carnivores, among mammals survived. Some omnivores, some insectivores, but mostly — carrion eaters.

  10. Stephanie, thanks so much for this knowledgeable account of a literally world-shattering event that made we and the world what it is today.

    This and Blake’s All Things Equine thread are my two nominees for MVPs of 2019. We gotta lotta Big Brains in this group, but you two have written a group of posts that shine out like supernovas. Cong Rats.

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