Revisiting Day One of the Cenozoic Era

Guest geology by David Middleton

Cenozoic Era: The Era of New Life

Figure 0. Cenozoic stratigraphic column. (ICS Subcommission on Quaternary Stratigraphy)

Who would have ever guessed that details about the first day of the Cenozoic Era might have been preserved the stratigraphic record?

Sep 09, 2019
Rocks at Asteroid Impact Site Record First Day of Dinosaur Extinction

AUSTIN, Texas — When the asteroid that wiped out the dinosaurs slammed into the planet, the impact set wildfires, triggered tsunamis and blasted so much sulfur into the atmosphere that it blocked the sun, which caused the global cooling that ultimately doomed the dinos.

That’s the scenario scientists have hypothesized. Now, a new study led by The University of Texas at Austin has confirmed it by finding hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.

The evidence includes bits of charcoal, jumbles of rock brought in by the tsunami’s backflow and conspicuously absent sulfur. They are all part of a rock record that offers the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs, said Sean Gulick, a research professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences.

“It’s an expanded record of events that we were able to recover from within ground zero,” said Gulick, who led the study and co-led the 2016 International Ocean Discovery Program scientific drilling mission that retrieved the rocks from the impact site offshore of the Yucatan Peninsula. “It tells us about impact processes from an eyewitness location.”

The research was published in the Proceedings of the National Academy of Sciences on Sept. 9 and builds on earlier work co-led and led by the Jackson School that described how the crater formed and how life quickly recovered at the impact site. An international team of more than two dozen scientists contributed to this study.


UT News

This bit is really interesting:

The evidence includes bits of charcoal, jumbles of rock brought in by the tsunami’s backflow and conspicuously absent sulfur.

While paleoclimatological evidence for a post-Chicxulub global cooling/darkening is limited (Vellekoop et al., 2014), the absence of sulfur-rich rocks in the crater backfill is a pretty good indication that the sulfur-rich evaporite rocks in the impact area were vaporized.

The first day of the Cenozoic

Highly expanded Cretaceous–Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by <1 m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt–water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.


The very high sediment accumulation rate in the crater enables very detailed resolution of the events 65 million years ago. While the exact day of the impact can’t be identified, the events of that day and the following weeks can be reconstructed in great detail.

The paper is pay-walled; but it might just be worth $10. The SI includes this seismic profile, showing how their core ties into the crater.

Figure 1. “(A) Seismic reflection image shown in depth with full waveform velocities overlain; line runs from southeast to northwest, including the location of Site M0077, and radially outward across the annular trough. The suevite interval within M0077, the focus of this paper, is shown in red, which maps to a low-velocity zone beneath the crater floor. The map in Inset shows the location of crater rings, drill sites (in the text), the seismic image, and the direction that ocean waters reentered the crater after formation. Expansion shows (B) representative core images in stratigraphic order with depths, (C) lithologic units, and (D) lithology.”

Just 60 km away from the impact site, the Yaxcopoil-1 CSDP core encountered a thick evaporite sequence just below the layer of impact breccia:

Lithologies of units A, C, D and F are dominated by dolomites and anhydrites and indicate restricted interior carbonate platform environments (Fig. 2). Dolomites were likely deposited in very shallow
subtidal to intertidal environments, as also indicated by the presence of mudstone lithologies, anhydrite nodules, laminated dolomite of likely stromatolitic origin, and the generally low abundance of megafossils (only rare bivalve fragments). Miliolids are often the only benthic
foraminifera recovered from these intervals and they are very rare. Alternating sequences of anhydrite and dolomite and massive anhydrite units are interpreted to indicate deposition in sabkha environments.

Stinnesbeck et al., 2004

Anhydrite (CaSO4) is one of the most common evaporite minerals.

Figure 2 from Stinnesbeck et al., 2004. Units A, C, D and F were dominated by dolomite and anhydrite (CaSO4).

It’s been estimated that the Chicxulub impact may have injected far more sulfate aerosols into the upper atmosphere than any other known Phanerozoic Eon impact event.

[T]he total sulfur degassing from the evaporite-rich sediments in the Chicxulub impact site may have led to formation of 3.8 × 1018 to 1.3 × 1019 g sulfate aerosol, and global atmospheric mass loading from the sulfate aerosol alone is estimated to be of the order of 1–2.6 g cm−2

Sigurdsson et al., 1992

To provide a frame of reference, Mount Pinatubo only injected about 20 million metric tons of sulfur dioxide into the stratosphere:

Several eruptions during the past century have caused a decline in the average temperature at the Earth’s surface of up to half a degree (Fahrenheit scale) for periods of one to three years. The climactic eruption of Mount Pinatubo on June 15, 1991, was one of the largest eruptions of the twentieth century and injected a 20-million ton (metric scale) sulfur dioxide cloud into the stratosphere at an altitude of more than 20 miles. The Pinatubo cloud was the largest sulfur dioxide cloud ever observed in the stratosphere since the beginning of such observations by satellites in 1978. It caused what is believed to be the largest aerosol disturbance of the stratosphere in the twentieth century, though probably smaller than the disturbances from eruptions of Krakatau in 1883 and Tambora in 1815. Consequently, it was a standout in its climate impact and cooled the Earth’s surface for three years following the eruption, by as much as 1.3 degrees F at the height of the impact.


In terms of sulfate aerosols, the Chicxulub impact could have been the equivalent of 190,000 to 1,900,000 Mount Pinatubos.

Had the impact occurred in an area devoid of sulfur-rich evaporites, the K-Pg extinction would have been far less severe.

Funny things

Mount Pinatubo injected about 20 million metric tons of sulfate aerosols into the stratosphere and caused about 0.7 °C of cooling, offsetting over 100 years of Gorebal warming for about three years. Pinatubo also injected about 50 million metric tons of CO2 into the atmosphere and caused no warming.

The Chicxulub impact put 190,000 to 1,900,000 Mount Pinatubos worth of sulfate aerosols into the upper atmosphere within a few days and left a big @$$ mark in the stratigraphic record. Humans have accounted for less than 1% of the cumulative CO2 emissions since 1751, yet we’re supposedly causing a “climate crisis” that rivals the PETM, Chicxulub impact and end-Permian extinction combined (Sarc?).

Did you ever wonder why past examples of volcanic greenhouse gas driven climate crises don’t seem to survive scrutiny?

While it has been proposed that intense volcanic release of carbon dioxide in the deep geologic past did cause global warming, and possibly some mass extinctions, this is a topic of scientific debate at present.


There is virtually no evidence that past volcanic releases of CO2 actually caused any discernible warming. Seawater pCO2 was higher before and after the oft-cited Paleocene-Eocene Thermal Maximum (PETM), which was sort of contemporaneous with the emplacement of the North Atlantic Large Igneous Province..

Figure 3.  Cenozoic CO2 atmospheric mixing ratio and seawater partial pressure.  Notice the huge difference between atmospheric CO2 and pCO2.  Also notice that pCO2 was higher before and after the PETM and that stomata data indicate that CO2 was about what it is today, apart from a short duration spike to about 800 ppmv 55.2 Mya.  Talk about settled science! Note: Older is to the right.  Tirpati should be Tripati.

Note how the PETM (55 Ma) is about as far from a CO2 analog to modern times as it possibly could be… unless the PETM stomata data are correct, in which case AGW is even more insignificant than previously thought.

Regarding temperatures, the PETM is also about as far from being an analog to modern times as it possibly could be.

Figure 4.  High latitude SST (°C) From benthic foram δ18O.  Funny how the PETM is often cited as a nightmarish version of a real-world RCP8.5… While the warmer EECO is a climatic optimum. (Zachos et al., 2001). Note: Older is to the right.

The Cretaceous and Paleogene Periods were warm. Whatever impact-related cooling that did occur, was of too short a duration to be resolved. But at least there’s some evidence for it. It has been postulated that the the initial effect of the Chicxulub impact was a sharp rise in temperature associated with the fireball and subsequent firestorms, followed by aerosol-induced cooling and then greenhouse warming (?)…

Figure 5. ” Impact ejected debris raining into and through the atmosphere caused severe swings in temperatures at the Earth’s surface.  Imagine, for a moment, you are in southern Colorado when the impact occurs. The temperature that day (or night) was normal (green dashed line) until the impact debris came screaming through the atmosphere.  Atmospheric temperatures rose dramatically (the first peak in the red line), possibly igniting fires in the surrounding bushes and trees. Twenty-four and forty-eight hours later, as Colorado rotated beneath the concentrated portion of that debris, the temperature spike twice more. After three to four days, however, most of the debris had reaccreted to Earth. The atmosphere was then choked with dust, soot, and sulphate aerosols, causing surface temperatures to dip below normal for a period of 5 to 10 years.  Once those particulates had rained out of the atmosphere, greenhouse gases caused temperatures to rise for probably thousands of years, although that number is still to be quantified.  This illustration was originally published by David A. Kring, 2000, Impact events and their effect on the origin, evolution, and distribution of life, GSA Today 10(8), pp. 1–7.Lunar and Planetary Institute

While there is evidence of the first two phases, the subsequent greenhouse warming is entirely speculative, based on recent assumptions about climate sensitivity to CO2. Assumptions that were largely scoffed at as recently as the late 1970’s.

Suggestion that changing carbon dioxide content of the atmosphere could be a major factor in climate change dates from 1861, when it was proposed by British physicist John Tyndall.


Unfortunately we cannot estimate accurately changes of past CO2 content of either atmosphere or oceans, nor is there any firm quantitative basis for estimating the the magnitude of drop in carbon dioxide content necessary to trigger glaciation.  Moreover the entire concept of an atmospheric greenhouse effect is controversial, for the rate of ocean-atmosphere equalization is uncertain.

Dott & Batten, 1976

The same assumption, that the high CO2 levels can be directly related to increased volcanic activity during the mid-late Cretaceous Period, is not well-supported by any observations, present or past.

Figure 6. Oceanic crust production and carbon dioxide (older is toward the right).

The highest Cretaceous CO2 levels preceded the 125-115 Ma peak in volcanic activity by 15 million years.

Nor is there a particularly good correlation between atmospheric CO2 and temperature…

Figure 7. Phanerozoic temperatures (pH-corrected) and carbon dioxide. The Miocene is the first epoch of the Neogene Period (Berner et al, 2001 and Royer et al., 2004) (older is toward the left).

If there was a clear relationship between volcanic activity, CO2 and temperature, we should see it in the rocks, particularly the basalt formations of the Columbia River Basalt Group (CRBG), the most recent, and best preserved flood basalt sequence.

According to Kashbohm & Schoene (2018)…

Flood basalts, the largest volcanic events in Earth history, are thought to drive global environmental change because they can emit large volumes of CO2 and SO2 over short geologic time scales. Eruption of the Columbia River Basalt Group (CRBG) has been linked to elevated atmospheric CO2 and global warming during the mid-Miocene climate optimum (MMCO) ~16 million years (Ma) ago. However, a causative relationship between volcanism and warming remains speculative, as the timing and tempo of CRBG eruptions is not well known. We use U-Pb geochronology on zircon-bearing volcanic ash beds intercalated within the basalt stratigraphy to build a high-resolution CRBG eruption record. Our data set shows that more than 95% of the CRBG erupted between 16.7 and 15.9 Ma, twice as fast as previous estimates. By suggesting a recalibration of the geomagnetic polarity time scale, these data indicate that the onset of flood volcanism is nearly contemporaneous with that of the MMCO.

Kashbohm & Schoene (2018)

It does appear that the timing of the vast majority CRBG eruptions can be fairly well tied down to a 700,000 to 900,000 year period coincident with the Mid-Miocene Climatic Optimum. However, even with the prodigious volume of CO2 associated with flood basalt eruptions, it’s not enough to significantly move the “climate needle”:

A statistic: It is estimated that an erupting basalt lava flow with a volume of 2000 km3 would release approximately 7 billion tonnes of carbon (or 26 billion tonnes of CO2).

This is about the same as the amount currently released by burning of fossil fuels – each year.

Saunders & Reichow

Armstrong McKay et al., 2014 estimated that the main phase of the CRBG eruptions, along with “cryptic degassing” of country rock, etc., emitted 4,090 to 5,670 billion tons of carbon over a 900,000 period. This only works out to 5-6 million tonnes of carbon per year… That’s an order of magnitude less than a rounding error. Our current 10 billion tonnes per year is only equivalent to 3% of the total annual sources in the Earth’s carbon budget. Self et al., 2005 found that CO2 emissions from flood basalt eruptions were insignificant relative to the mass of CO2 in the atmosphere and unlikely to have played a signifcant role in past episodes of “global warming.” Although they did note that the sulfur gas emissions may truly have been unprecedented.

While the impact of volcanic S gas release may be profound, the mass of CO2 directly released by individual flood lava eruptive events is tiny in comparison to the normal mass in the troposphere and stratosphere. The predicted increases in atmospheric concentration are a fraction of the current anthropogenic CO2 released from hydrocarbon burning (~25 Gt per year). Moreover, while the amount of CO2 in the atmosphere is currently ~3000 Gt, it was perhaps double this value during the late Cretaceous (i.e. ~6000 Gt). It is therefore unlikely that volcanic CO2 had a direct effect on mechanisms of global warming, supporting earlier findings by Caldeira and Rampino (1990). In addition, there would have been more than sufficient time for the extra mass of CO2 added to equilibrate, given that the lava-forming eruptive events must have been spaced at least hundreds, and probably thousands, of years apart. By contrast, SO2 emissions and the atmospheric burden of sulfate aerosols generated during flood basalt events appear to be unprecedented at any other time in Earth history. Acid rain may also have been widespread. What is less certain is whether affected biota would have had time to recover from the deleterious effects of sulfate aerosol clouds and acid rain, although quiescent intervals lasting millennia appear to offer ample time for the recovery of local biological and environmental systems (Jolley 1997).

Self et al., 2005

We can’t even be certain that the atmospheric concentration of CO2 during the Mid-Miocene Climatic Optimum was significantly elevated relative to the extremely low values of the Quaternary Period.

Figure 8. Neogene-Quaternary temperature and carbon dioxide (older is toward the left).

We can see that CO2 estimates for MMCO range from 250 to 500 ppm, rendering any efforts to draw conclusions about the CRBG and MMCO totally pointless. According to Pagani et al, 1999:

There is no evidence for either high pCO2 during the late early Miocene climatic optimum or a sharp pCO2 decreases associated with
EAIS growth.

Pagani et al., 1999

Pagani et al., suggest that changes in oceanic circulation driven by plate tectonics (opening of the Drake Passage) and the presence (or lack thereof) of a large polar ice sheet were the primary drivers of Miocene climate change, not volcanic activity. Same as it ever was…

FORECASTING THE FUTURE. We can now try to decide if we are now in an interglacial stage, with other glacials to follow, or if the world has finally emerged from the Cenozoic Ice Age. According to the Milankovitch theory, fluctuations of radiation of the type shown in Fig. 16-18 must continue and therefore future glacial stages will continue. According to the theory just described, as long as the North and South Poles retain their present thermally isolated locations, the polar latitudes will be frigid; and as the Arctic Ocean keeps oscillating between ice-free and ice-covered states, glacial-interglacial climates will continue.

Finally, regardless of which theory one subscribes to, as long as we see no fundamental change in the late Cenozoic climate trend, and the presence of ice on Greenland and Antarctica indicates that no change has occurred, we can expect that the fluctuations of the past million years will continue.

Donn, William L. Meteorology. 4th Edition. McGraw-Hill 1975. pp 463-464

Despite only having 12 years to solve the “climate crisis,” we are still living in an Ice Age, and will be so long as Antarctica remains isolated over the southern polar region, Greenland retains its ice sheet and the northern polar region retains at least seasonal ice cover.

Figure 9. From Zachios et al., 2001 (older is toward the bottom).

The roughly 1.0 °C of warming since the coldest climatic period of the Holocene, the Little Ice Age, hasn’t budged us out of the Quaternary Period temperature “noise level.”

Figure 10. High Latitude SST (°C) From Benthic Foram δ18O (Zachos, et al., 2001) and HadSST3 (Hadley Centre / UEA CRU via plotted at same scale, tied at 1950 AD (older is toward the left).

Another 0.5 to 1.0 ºC between now and the end of the century doesn’t even put us into Eemian climate territory, much less the Miocene or even the Pliocene. We will still be in the Quaternary Period noise level. Bear in mind that the instrumental temperature data are of much higher resolution than the δ18O derived temperatures. As such, the δ18O data reflect the bare minimum of dynamic amplitude range. Actual paleo temperatures would have reflected a far greater range of variability (higher highs and lower lows).

On the other hand, a Chicxulub-style impact could easily slap our rather cold climate back into Pleistocene glacial conditions faster than the Green New Deal could destroy our robust economy.


Armstrong McKay, David, Toby Tyrrell, Paul A. Wilson, & Gavin Foster. (2014). “Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study”. Earth and Planetary Science Letters. 403. 254–262. 10.1016/j.epsl.2014.06.040. Special thanks to David Armstrong McKay for kindly sending me a copy of his paper.

Berner, R.A. and Z. Kothavala, 2001. GEOCARB III: A Revised Model of Atmospheric CO2 over Phanerozoic Time, American Journal of Science, v.301, pp.182-204, February 2001.

Donn, William L. Meteorology. 4th Edition. McGraw-Hill 1975. pp 463-464

Dott, Robert H. & Roger L. Batten.  Evolution of the Earth.  McGraw-Hill, Inc.  Second Edition 1976.  p. 441.

Gulick, Sean P. S.,  et al. “The first day of the Cenozoic”. Proceedings of the National Academy of Sciences Sep 2019, 201909479; DOI: 10.1073/pnas.1909479116

Illis, B. 2009. “Searching the PaleoClimate Record for Estimated Correlations: Temperature, CO2 and Sea Level”. Watts Up With That?

Kasbohm, Jennifer, and Blair Schoene. “Rapid Eruption of the Columbia River Flood Basalt and Correlation with the Mid-Miocene Climate Optimum.” Science Advances, American Association for the Advancement of Science, 1 Sept. 2018,

Pagani, Mark, Michael Arthur & Katherine Freeman. (1999). “Miocene evolution of atmospheric carbon dioxide”. Paleoceanography. 14. 273-292. 10.1029/1999PA900006.

Pearson, P. N. and Palmer, M. R.: Atmospheric carbon dioxide concentrations over the past 60 million years, Nature, 406, 695–699,, 2000.

“Rate of Ocean Crust Production.” lect7-4, University of Leicester,

Royer, D. L., R. A. Berner, I. P. Montanez, N. J. Tabor and D. J. Beerling. “CO2 as a primary driver of Phanerozoic climate”.  GSA Today, Vol. 14, No. 3. (2004), pp. 4-10

Self, Stephen & Thordarson, Thorvaldur & Widdowson, Mike. (2005). “Gas Fluxes from Flood Basalt Eruptions”. Elements. 1. 10.2113/gselements.1.5.283.

Sigurdsson, H., S. D’Hondt, S. Carey, “The impact of the Cretaceous/Tertiary bolide on evaporite terrane and generation of major sulfuric acid aerosol”.
Earth and Planetary Science Letters. Volume 109, Issues 3–4, 1992, Pages 543-559, ISSN 0012-821X,

Stinnesbeck, Wolfgang, et al. “Yaxcopoil-1 and the Chicxulub impact”. Int J Earth Sci (Geol Rundsch) (2004) 93: 1042–1065
DOI 10.1007/s00531-004-0431-6

Tripati, A.K., C.D. Roberts, and R.A. Eagle. 2009.  “Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years”.  Science, Vol. 326, pp. 1394 1397, 4 December 2009.  DOI: 10.1126/science.1178296

Vellekoop, Johan, et al. “Rapid short-term cooling at K–Pg boundary”. Proceedings of the National Academy of Sciences May 2014, 111 (21) 7537-7541; DOI: 10.1073/pnas.1319253111

Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, K. “Trends, rhythms, and aberrations in global climate 65 Ma to present”. Science 292, 686–-693 (2001).

155 thoughts on “Revisiting Day One of the Cenozoic Era

  1. How far beneath the KT boundary are the last dinosaur fossils?
    Dino’s were big flightless birds.
    The flying Dinos survived.
    When these critters lose their flying ability their days are numbered.

    • The secret to survival in not being present at the location where Darwin awards are being handed out. The dinosaurs did not immediately become extinct. The birds, related to dinosaurs, were able to rapidly cross mountain ranges, rivers, deserts, and to move to locations more favorable to their survival. Birds still optimize their environment by migrating to more favorable conditions with the seasons.

      • Most birds were wiped out with their larger, flightless kin. The most abundant and diverse group of Mesozoic birds (avialans), the Enantiornithes or “opposite birds” went extinct, plus all the even more “primitive” avialans of the end Cretaceous and many of the closest relatives of modern birds as well.

        A very few lucky species of paleognaths, galloanserae and neoaves managed just barely to survive. One group lucked out by being on Antarctica, far from the worst effects of the impact, and because they were water birds. Another survived by being small seed-eaters.

        As with mammals, crocodylians, lizards (including snake ancestors), tuataras, turtles, certain fish, etc. among vertebrates every major class had a few species which managed to make it through.

        • You know more than me by quite a bit!
          Can you tell me how close to the KT boundary line are dinosaur fossils found?

          • I have to reply to myself! I followed the link given by John Tillman below to the KT boundary and the dinosaurs:
            “None of these details are in the study, however. No dinosaur bones are mentioned in the main study, and the supplement highlights only one hip-bone fragment from a horned dinosaur like Triceratops, found with “associated impressions of tissue.” (The New Yorker claims that a suitcase-size piece of fossilized skin is attached to the bone fragment.)”

            Look. If the dinosaurs were doing just fine and dominating the land until the day of the big hit, there should be abundant dinosaur fossils just below the KT boundary and none above it.
            As best as this amateur can tell, this is just not the case.
            So, color me unconvinced.
            BTW, but not completely OT, Darwin recognized that the fossil record, with its huge gaps and sudden changes in fossil types, was inconsistent with his theory of evolution by gradual, almost imperceptible changes.

          • Joel,

            Even large herds of animals occupy a very small space upon the panet’s surface. You should not expect to find fossils under evert square meter of Cretaceous/Paleogene boundary, which in any case doesn’t crop out in many places.

            However we do have sites right at the boundary with non-avian dinosaurs below and in it, and none above it. The Dakota site is rare and valuable because it records the very day of doom.

            Neither Darwin, nor any scientist since, has regarded sudden extinctions as incompatible with the fact of evolution. Indeed, discovery of the fact of extinction by Cuvier in 1798 was critical to the later discovery of the fact of evolution by Darwin and Wallace.

            Evolution can be gradual over many generations or occur in a single generation.

          • Also… Most fossil assemblages are of marine invertebrates. Vertebrate, particularly terrigenous vertibrate, are not as well preserved in the fossil record.

        • Just like a Jukebox, ……. push a button, …….. and it repeats the same ole song.

          Well now, for the $10 million dollars in Grant monies they had better come up with a frightening story or they won’t get any more Grants.

          Three excerpts from the article:

          the impact set wildfires, triggered tsunamis and blasted so much sulfur (hundreds of billions of tons of sulfur from pulverized ocean rock) into the atmosphere that it blocked the sun,

          has confirmed it by finding hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.

          the evidence includes bits of charcoal, jumbles of rock brought in by the tsunami’s backflow and conspicuously absent sulfur.

          HA, ……no sulfur ….. but specks of burned biomass.

          My questions are, …… where did all the sulfur go after decades of “blocking” out the Sunshine …. and where did all the rocks come from for “backfilling” the crater.

          Was the in-rushing tsunami’s “backflow” a 24+ hours long ordeal …… and iffen global temps dropped 30 degrees F and Sunshine was blocked from months to decades, how was it possible for any land plant or creature to have survived?

          And such “selective” extinctions don’t make good sense, to wit:

          a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth became extinct, including all non-avian dinosaurs.

          So, the non-flying dino-birds survived, ……. HUH? A miracle perhaps?

          The logical explanation for the demise of the dinosaurs is as follows:

          Fossil records infer that the time period from about 252 mya to about 66 mya was the “Age of the Dinosaurs”. And if one plots said “Age of the Dinosaurs” on the Figure 7 graph (in the above published article) of “temperature & CO2”, ….. it becomes readily observable that the “rise” of the dinosaurs began when atmospheric CO2 began to increase above 1,000 ppm.

          And said dinosaurs thrived, evolved and multiplied, especially during the 80 million years when atmospheric CO2 was at or above 1,800 ppm. They were the dominant species, both herbivores and carnivores.

          But atmospheric CO2 began decreasing at the 120 mya “mark”, thus decreasing below the 1,000 ppm level at around 66 mya, … with the decrease in dinosaur populations following suite …… and they disappeared from the fossil record at around 66 mya, ……. and the Age of the Dinosaurs had ended as a result of their starving to death..

          • Samuel,

            Non-avian dinosaurs means all dinosaurs which aren’t modern birds. It doesn’t mean just the nonvolant dinobirds, ie non-avian maniraptors.

            The vaporized S came down all over the world. The rock came from around the crater, as shown in David’s imagery.

            Dinosaurs and all the other organisms which went extinct at the end of the Cretaceous didn’t die for lack of CO2, which was still three times present levels or more, ie at ideal levels for C3 plants. Flowering plants, ie angiosperms, flourished during the Late Cretaceous, prompting the evolution of dinosaurs to eat them, such as the hadrosaurs and ceratopsians upon which tyrannosaurs fed.

            The many other terrestrial and marine species which were wiped out ~66.5 Ma clearly weren’t suddenly killed by CO2 going from 1300 to 1200 ppm. Even had it fallen to 900 ppm, most C3 plants would still be happy.

          • Destruction of literally Biblical proportions…

            While the subsequent greenhouse warming is speculative, the rest of the Hell-on-Earth checklist is fairly well documented. The initial earthquakes could have been the equivalent of >11 magnitude. The tsunamis and/or seiches would have been unimaginable. And the reentering ejecta could have ignited wildfires over most of the Earth’s surface.


          • Where did the sulfur go? All over the world.
            Where did the rocks come from? All over the Caribbean.
            Was the backflow a 24+ hour ordeal? Definitely. A hole several miles deep and several hundred miles across was blasted into the floor of a shallow sea. How long do you think it would take for the water to flow back in.

            So this 20 million long starvation event managed to cause all dinosaurs to die at almost the same time overnight. Not a single one was able to adapt to the changing world over that 10 million year period?

          • Good questions Samuel!

            I’ll add my question to your list.

            Why do these researchers assume anhydrite? Obviously, it’s because evaporites, i.e. specifically the evaporite anhydrite, calcium sulfate.
            Claiming to find anhydrites and evaporites at a layer immediately below the impact layer sixty kilometers away obfuscates the question; why assume anhydrites at the Chicxulub location?

            Anhydrite is CaSO₄.
            Dolomite is CaMg(CO&#8323)₂.

            The Chicxulub crater is still well defined, even after 65 million years. Chicxulub’s crater is currently under water and quite likely was under water 65 million years ago.

            Just another climate alarmist phenomenon where a possibility is theorized; Then reality is adjusted until they find a path to their assumptions. An assumption then used as proof toward the researchers preferred result.

            These researchers need to find physical evidence of sulfur deposition along with the abundant global samples of iridium from the Chicxulub fallout age layer worldwide. Give up presuming to psychically deduce results based upon a lack of evidence.

          • Because the rocks around the impact site are loaded with anhydrite and other rocks indicative of a shallow restricted marine or sabkha depositional environment.

          • They are assuming that the area underneath the crater, prior to impact, was the same as the areas surrounding the crater.

          • MarkW – September 11, 2019 at 4:04 pm

            Where did the sulfur go? All over the world.

            Great question, Mark, ….. and I will tell you where it went ….. if no one else will.

            Yup, all over the world, Mark, …… and falling as “a rain of death” to all asteroid surviving plants and animals, to wit:

            Acid Rain -Because the Chicxulub impact occurred in a region with rocks composed of the mineral anhydrite, which is a calcium sulphate mineral, sulfur vapor was also injected into the stratosphere. That sulfur, reacting with water vapor, produced sulphate aerosols and eventually sulfuric acid rain. This effect was completely unanticipated until the Chicxulub impact site was discovered. It may also be one of the more serious environmental consequences of that impact event.

            The ”die off” had to be far, far bigger than the “experts” are telling you.

          • John Tillman – September 11, 2019 at 2:42 pm


            Non-avian dinosaurs means all dinosaurs which aren’t modern birds. It doesn’t mean just the nonvolant dinobirds, ie non-avian maniraptors.

            GIMME A BREAK, …. Tillman, …. I am not a “clueless” undergrad sucking-up for a “passing grade.”

            “DUH”, modern birds are not dinosaurs …… and you don’t have a frigging clue which dinosaur species that birds evolved from.

            But it matters not, the “experts” are still claiming a “highly selective” surface dwelling extinction event.

          • I used to be of the opinion that modern birds technically weren’t dinosaurs; but had evolved from dinosaurs. However, most paleontologists now consider birds to be nonavian dinosaurs…

            Ask your average paleontologist who is familiar with the phylogeny of vertebrates and they will probably tell you that yes, birds (avians) are dinosaurs. Using proper terminology, birds are avian dinosaurs; other dinosaurs are non-avian dinosaurs, and (strange as it may sound) birds are technically considered reptiles. Overly technical? Just semantics? Perhaps, but still good science. In fact, the evidence is overwhelmingly in favor of birds being the descendants of a maniraptoran dinosaur, probably something similar (but not identical) to a small dromaeosaur.


            While there will never be 100% certainty about this, it is the current paradigm.

          • John Tillman – September 11, 2019 at 6:09 pm

            The evidence is overwhelming and predates identification of the Yucatan crater as the impact site. From 1992:

            Shur nuff, a geologists discovered a “result”, an “iridium layer” in the rock strata, …. that predated the search for a “cause”, …… and latching onto the 1st one that would “fit the bill”.

            Oceanic anoxia at the cretaceous/tertiary boundary supported by the sulfur isotopic record

            “YUP”, ….. and there is also a lot of “junk science” claims that are supported by questionable interpretations of the contents of Antarctica “ice cores”.

          • That’s how geology works. It starts with observations, forms a hypothesis and then tests that hypothesis with subsequent observations. It’s more or less how all science works.

            Observation: Traditional dinosaurs along with about 75% of contemporary species vanish from the fossil record rather suddenly at the end of the Cretaceous Period and Mesozoic Era.
            Hypothesis: A rather sudden mass extinction occurred, cause unknown. Possibly climate change, volcanic activity, impact event.

            Observation: The Cretaceous-Paleogene (K-Pg) boundary is enriched in iridium. This feature is determined to be golbal.
            Hypothesis: A major impact event occurred. This could explain the K-Pg extinction.

            Observation: The Chicxulub impact crater is discovered by Pemex while drilling an oil prospect. The crater is mapped in detail with geophysical and well data. It is at the K-Pg boundary and it is massive.
            Hypothesis: The Chicxulub impact is a strong candidate as the proximal cause of the K-Pg extinction.

            Since then, all of the subsequent observations have reinforced this hypothesis. I don’t think there has been another geological hypothesis that has been so thoroughly reinforced by subsequent observations, with virtually no contradictory observations. The math of the anhydrite vaporization is the mother of all QED’s.

          • David Middleton – September 12, 2019 at 7:33 am

            However, most paleontologists now consider birds to be nonavian dinosaurs…

            So, are you saying that birds are actually non-bird dinosaurs? Or that non-dinosaur birds are really not birds?

            David, getta clue from an old school biologist, …… iffen it’s “avian” ……. it’s a “bird”, to wit:

            a·vi·an (ā′vē-ən) adj. Of, relating to, or characteristic of birds.
            avian (ˈeɪvɪən) adj (Zoology) of, relating to, or resembling a bird
            a•vi•an (ˈeɪ vi ən) adj. of or pertaining to birds.
            a·vi·an (ā′vē-ən) Relating to birds.


          • I meant to say “avian dinosaurs”… Most paleontologists now consider birds to be avian dinosaurs.

          • David Middleton – September 12, 2019 at 7:51 am

            That’s how geology works.

            I know how geology works. My AB Degree with a minor in/of the Physical Sciences insured said.

            with about 75% of contemporary species vanish from the fossil record rather suddenly at the end of the Cretaceous Period and Mesozoic Era.

            HORSEFEATHER, …… David, ……. I dun tolt ya that all fossils are “accidents”, because no one or no thing buried any plants or plant remains, …….or any animal, animal remains or animal carcasses …. on purpose of/for the purpose of …… creating a fossil.

            Thus said, for all we, … you, know, ……various dinosaurs could have “subsistence” survived for another 10 to 100 million years after the “claimed” 66 mya asteroid impact.

            David M, maybe you should try to explain why so many geologists think, believe and/or claim that the Grand Canyon of the Colorado …… was formed/created by the erosive force of the Colorado River.

            And/or maybe you should explain why they found an asteroid caused “iridium layer” …… but have never found an asteroid caused “sulfur layer”, given the fact that they also claim, to wit:

            “ the impact set wildfires, triggered tsunamis and blasted so much sulfur (hundreds of billions of tons of sulfur from pulverized ocean rock) into the atmosphere that it blocked the sun,

          • The rock containing the sulfur was vaporized. The SO2 and other aerosols would have eventually settled out of the atmosphere diffusely; there wouldn’t be a concentrated sulfur layer and more than there would be a concentrated carbon layer if atmospheric CO2 slowly declined. The iridium-rich layer is from the ejecta which landed all over the Earth’s surface in a matter of hours to days. Sulfur, calcium and oxygen are common elements in Earth’s crust. Iridium is not.

            The fossil record above the K-Pg boundary is totally different than the fossil record below it. While only a small percentage of animals and plants are preserved as fossils, the time at which they vanish from the fossil record is when they became extinct. While some species, long thought to be extinct, turn out to be alive and well (like the coelacanth). Non-avian dinosaurs vanished from the fossil record after the end of the Cretaceous and have not, as yet, recovered from extinction like the coelacanth.

            The “Colorado River” would include all of its tributaries and ephemeral streams that drain that portion of the Colorado Plateau.

            While it’s certainly possible that an ancestral canyon system pre-dates the Grand Canyon, the current canyon was carved by the Colorado River…

            How was the Grand Canyon formed?

            The specific geologic processes and timing that formed the Grand Canyon spark lively debates by geologists. The general scientific consensus, updated at a 2010 conference, holds that the Colorado River carved the Grand Canyon beginning 5 million to 6 million years ago.

            However, recent advances in dating techniques have upended the notion of a uniformly young Grand Canyon. The new approach determines when erosion uncovered rocks in the canyon. The big picture: there were two ancestral canyons, one in the west and one in the east. And the western canyon may be as old as 70 million years. [For more on the Grand Canyon’s formation, see New Clues Emerge in Puzzle of Grand Canyon’s Age]


          • Samuel C Cogar September 12, 2019 at 7:03 am

            We know from which dinosaur group modern birds arose, namely maniraptors, many species of which shared derived traits with modern birds.

            We also know some of the Cretaceous species which survived the mass extinction event to become ancestral to present birds, or were very closely related to those ancestors.

            Birds are phylogenetically dinosaurs because they are descended from dinosaurs. Humans are apes, simians, haplorhines, primates, mammals, synapsids, amniotes, tetrapods, sarcopterygians, euteleostomes, vertebrates, chordates, etc., because we are descended from those more inclusive clades.

            Similarly, birds are avialans, maniraptors, theropods, dinosaurs, archosaurs, diapsids, amniotes, tetrapods, sarcopterygians, euteleostomes, vertebrates, chordates, etc.

          • The furcula or wishbone, once thought diagnostic of birds, now is known to go far back in theropod evolution:

            A Furcula in the Coelophysid Theropod Syntarsus


            It turned out that the generic name Syntarsus had already already taken by a beetle, so the dinosaur was renamed Megapnosaurus, but many subsequent studies have classified it in the genus Coelophysis. It lived in the earliest Jurassic.

          • David M, ……. people like you with “tunnel vision” sees the Grand Canyon of the Colorado as
            looking like this

            Whereas people like myself who have “wide-angle vision” sees the Grand Canyon of the Colorado as looking like this ……… because we are intelligent enough to know that “river erosion” could not have possibly created the topography of an 18 mile wide section of the primary channel in the middle portion of the drainage area, ….. with vertical side wall up to a mile high and with dozens of side-channels having been eroded far back into said sidewalls at various locations.

            “DUH”, it is obvious to me that it was the “uplifting” of the Colorado escarpment that caused the “fracturing” of the surface topography, just like this earthquake caused “fracturing” of the surface topography.

            David, if all that you and John Tillman are capable of doing is “mimicking” and/or “repeating” what you were instructed to learn in/at school or you read from a book, a report or a published abstract, then you will never be any more learned than your chosen mentors are.

            I don’t like playing “Mimicry” …… or ……. “Battling Urls”.

            Cheers, Sam C

          • Few people are so eager to share their utter ignorance.

            Shur nuff, David, ….. and I’m happy to share more of my ignorance with you, …. in hopes that you might explain to me how “Colorado River erosion” managed to create the Grand Canyon “landscape” that is pictured hereon this website:

            Now I wasa employing my ignorance by thinking that iffen there was a super-duper-size Lake Agassiz that was breached ….. and all the water rushed down the Colorado river channel in 48 hours, it mighta cudda resulted in the pictured erosion.

            But I’m sure you have a legit sci-fi explanation for said.

          • Nothing in the link contradicts anything I posted or supports the idiotic notion that the canyon could have formed in “48 hours.”

      • But, since Dino’s were the dominant land animal, being so superior to mammals and all, they would have already been in those favorable environments before the meteor hit. They would not have had to fly there.
        That is my big hangup on this theory of Dino extinction.
        Every single one went extinct, immediately they say.
        I suspect that having to hang around and defend a ground nest (they didn’t bury their eggs as I understand it, but had to probably incubate them and guard them), just was a losing reproductive strategy in the long run.

        • Larger animals suffered worse than smaller, which of course includes birds. Some mammals survived by burrowing and eating plant material which wasn’t burnt up or by scavenging. Aquatic terrestrial creatures also did better.

        • Large animals in general went extinct, whether marine or terrestrial.

          But the particular biochemical conditions and lifestyle or organisms also figured in who made it and who didn’t.

        • What’s favorable before the meteor hit may not be the most favorable for surviving the devastation of the meteor.

          For example, animals that burrow generally do so because they aren’t able to survive on the surface. However being underground during those temperature spikes would greatly enhance your chances of survival. The large animals that dominated the surface quickly became BBQ.

          • Flying is like having a car or helicopter when others must walk. That great mobility is what saved some of them.

          • If that were all there was to it, then bigger dinosaurs should have fared better. Long legs means you can walk faster and further.

          • Joel,

            I’m not sure of the point you’re trying to make.

            Ground-nesting flightless birds obviously survive, or there would be no ostriches, emus, cassowaries, kiwis, rheas, Aukland Island or Campbell teals, steamer ducks, Junin or Titcaca grebes, flightless cormorants, wekas and other flightless rails, penguins and kakapos.

            Yes, many vulnerable flightless birds were wiped out when mammals were let loose on oceanic islands, but obviously not all. Far from it.

          • PS: Please note that many on my short list are species which managed to survive the arrival on their islands or continents of humans and other mammalian invaders.

        • joel – September 10, 2019 at 7:48 pm

          they would have already been in those favorable environments before the meteor hit. They would not have had to fly there.

          Joel, you are correct.

          Dinosaurs were already in those favorable environments, ….. on every continent, …. long before the “claimed” suspect asteroid hit the surface of what is now known as the Yucatán Peninsula in Mexico, ….. therefore rendering said asteroid “strike” as highly improbable.

          Or, on the contrary, the “claimed” suspect asteroid most likely hit the surface of what is now known as the Yucatán Peninsula in Mexico long time before (pre-252 mya) the dinosaurs ever evolved to prominence in the Animal Kingdom.

          joel – September 10, 2019 at 7:48 pm

          I suspect that having to hang around and defend a ground nest (they didn’t bury their eggs as I understand it, but had to probably incubate them and guard them), just was a losing reproductive strategy in the long run.

          Joel, that same “reproductive strategy” that you question ……. is currently being employed by dozens n’ dozens of different species now days, and they are surviving just fine.

          • The impact is not only not improbable, but a fact, ie a scientific observation of nature.

            Some have questioned whether it alone caused the mass extinction event at the end of the Cretaceous, but never convincingly.

            The conditions following the impact were so hellish, it’s a miracle that as many species, genera, families, orders and classes survived as did. The pattern of survival reinforces the impact as the main, indeed probably sole, cause.

          • I used to lean toward the Deccan Traps eruptions as a major cause of the extinction… But the evidence of nearly global destruction from this impact has been accumulating for nearly 40 years, with essentially no contradictory evidence. Few geological hypotheses have been so well supported.

          • Mark,

            Even before finding the crater, signs of the space rock collision were found all around the world. The Alvarezes first found the iridium layer in Italy. Impact detritus is greatest in the Caribbean, then thins out from there.

            In 1953, geologists of doom Kelly and Dachille had first suggested a celestial impact as the cause of a number of unexplained phenomena, to include the sudden disappearance of the dinos. Even earlier such speculations lacked evidence.

          • I am referring to bird like animals, warm blooded. There are very few of those who ground next and are flightless, and every time dogs and rats and cats get onto an island where birds have lost their flying ability, the flightless birds go exist.

      • “What is better than presence of mind during a disaster?”
        “Absence of body!”

        (old Punch magazine joke)

    • The Archaeoptrix, that icon of the bird missing-link actually went extinct. So Dino’s were not birds. Even Raptors had feathers, used again and again in biospheric epochs.
      Modern bird bone has quite a diiferent makeup than Dino bones (chemical elements).
      So why did some species survive and others not?

      And there is the question if the Dino extinction had already begun before the impact?

      Kinetic explanations are always attention-grabbers. Better not to miss life for the stones!

      So where was the solar system then, above or below the galactic plane, and traversing which spiral arm?

      • Birds are indeed dinos. Modern birds probably aren’t directly descended from Archaeopteryx, but from other maniraptoran theropods closely related to it. They too of course went extinct, as eventually do all species.

        Avian bones are very similar to those of theropods and sauropods, in that all contain air sacs. Its rare to find sauropod skulls, since they were relatively small and thin-walled.

        It is now theoretically possible to turn back on the standard theropod genes in birds that evoution has turned off. To make a chickenosaurus with theropod traits, you’d have to do in one embryo what has been done separately in different embryos. Scientists have turned on the genes for teeth and snout instead of beak; for long, bony tails rather than pygostyle; for dino-style feet and stance, etc.

        Even today some birds still grow claws rather than fusing two of their three finger bones together. The “thumb” remains free to act as the alula, a leading edge slat for high angle of attack landings.

        Birds even share medullary bone, today unique to birds, with T. rex, a near relation of maniraptors:

      • Some paleontologists have argued that dino diversity was lower in the Maastrichtian Age than Campanian, but this view has been challenged, IMO successfully. Non-avian dinos were not on their way out during the latest Cretaceous. Indeed, diversity was probably increasing, thanks to the continents’ drifting apart. The impact did them in.

        For instance, there was great diversity in birds, with representatives of modern groups present, others related to moderns, but still with teeth, the more numerous opposite birds and surviving clades less derived than Enantiornithes (opposites) and Ornithurae (moderns and their closest toothed relatives, such as seabird Ichthyornis and almost wingless oceanic diver Hesperornis).

        It also turns out that pterosaurs were more diverse in the Maastrichtian than previously thought. Other groups besides giant azhdarchids have been convincingly recognized recently.

    • The articles aren’t about the discovery of the Ir-rich K-Pg boundary layer, or whether or not a major impact occurred. That said, I wouldn’t be surprised if Alvarez was cited by some of the references.

  2. Appreciate your posts, Mr. Middleton. Retired petroleum geologist who marvels at the effort you put into pulling all the information together for them. That they also include a fair amount of wit sweetens it all.

  3. Examining Figure 7, the difference in temperature between pre-industrial CO2 levels and when levels were 1000 ppm is only about 2C which also includes all other possible influences. How is it supposed to be nearly 6C after being doubled almost twice? About 1C per doubling is less than the IPCC’s lower bound, but is near the middle of the sensitivity estimates by skeptics.

    • This “climate sensitivity” is whatever somebody wants it to be, make it all up as needed.

      The terrible skeptic (me) has never seen actual proof that this value is positive. Only “upper bounds” of it.

      • The only upper bound that can be supported by the physics is an emissions sensitivity of 2 W/m^2 of surface emissions per W/m^2 of forcing. The current average for the Earth is 1.62 W/m^2 per W/m^2 of forcing and an ideal BB is only 1 W/m^2 per W/m^2. The applicable laws of physics are deterministic and so is the sensitivity as a function of those laws. The uncertainty attributed to it by the IPCC is far too large to be called ‘settled’, yet the actual maximum possible sensitivity isn’t even within the presumed range.

        The next W/m^2 will have an effect no different than the average W/m^2, or about 1.62 W/m^2 of surface emissions per W/m^2 of forcing, corresponding to about 0.3C per W/m^2 or about 1.1C for doubling CO2 which as a change to the system is said to be equivalent to about 3.7 W/m^2 of real solar forcing.

        • I have no problem with black body radiation, nor spectrally selective surfaces, I have a problem with “climate sensitivity” as the ratio of two quantities that cannot be given a strict definition from measurement, even operationally.

          • Yep… The translation from ballpark estimates of radiative forcing to temperature is almost entirely speculative.

          • The climate sensitivity as defined by the IPCC is pure speculative garbage and is completely decoupled from its physical manifestation, however; the slope of the SB equation is an EXACT quantification of the sensitivity of either a black or a gray body. This is given exactly as dT/dE = 1/(4eoT^3), where T is the temperature of the surface, E are the emissions a TOA, o is the SB constant and e is the effective emissivity, which for the Earth is 0.62 and for a black body, e=1.

            Every IPCC report seems to add more levels of obfuscation between the physical sensitivity and what they call the sensitivity. The only legitimate units for a physical sensitivity are W/m^2 of surface emissions per equivalent W/m^2 of forcing. It has now been ‘converted’ into a temperature change per equivalent doubling of CO2 completely decoupling it from its physical basis.

            They can’t use the proper units for the physical sensitivity because when the IPCC nominal sensitivity is back converted into W/m^2 of surface emissions per W/m^2 of forcing, it becomes 4.4 W/m^2 of incremental surface emissions per W/m^2 of forcing which is obviously impossible, especially considering that the average physical sensitivity is only 1.62 W/m^2 of surface emissions per W/m^2 of forcing. There’s simply no possible way to distinguish the next W/m^2 from the average W/m^2 so that it can be so much more powerful at warming the surface than any other.

  4. Good collection of the event, David. I had to look “suevite”, it is a glassy matrix breccia of impact origin. Where I have done extensive field work in the Neuquen Basin of Argentina the dinosaur fossilized bones are abundant right up to the extinction, which is an incredible event, considering it was world-wide. I actually looked for dinosaur bones as they collected uranium and copper from any solutions moving around in the basin and were often guides to nearby deposits.

  5. Interesting, but I’m not sure about the sulfur concentrations. I guess they are basing that on the sulfur concentration surrounding the impact site. I’m not sure if that just incidental to the distribution of the mineral that was there to begin with, or the distribution of bacteria etc that concentrated sulfur within that region.

  6. There must be a lot of heat coming from the lava flow.
    In the big scheme of things it might not be significant.
    Currently live near the edge of the CRB, now folded and broken.

  7. Whether or not the sulfur was involved, isn’t it possible that the hugh quantity of ‘stuff’ from the impact in the atmosphere blocked tha sunlight for long enough [several years??] so that the dinosaurs simply starved to death? No plants to eat…etc…etc.

    • @ nw sage.

      Iffen the impact “particulate” stuff in the atmosphere, …..blocked the sunlight for long enough [several years??], …… then all land animals and plants on the surface would have died, along with a majority of aquatic animals and plants living in streams, rivers, lakes and oceans.

      Only the plant biomass that reproduced by seeds (maybe a few roots and tubers) could have withstood several years of “darkness” and decreased surface temperatures.

      • As you say, seeds would have survived.
        Even if dead, the plants would have provided food for animals that ate plants.
        With the cold, dead animals would not have rotted quickly and would have provided food for scavengers for a long time.

        • MarkW – September 11, 2019 at 4:12 pm

          Even if dead, the plants would have provided food for animals that ate plants.

          Mark, the BIG problem you have with the above is ……. the “several years of “darkness”.

          Many animals can “see” pretty good in semi-darkness conditions, ……. but not in total darkness. I think some animals can “see” IR, but there is no IR if the prey animal is dead. And some can “see” with their nose, but that has limitations in total darkness

          But worse than that, …… all the editable plant food would soon (3/4 weeks) be eaten up, decomposed or frozen solid.

          • The darkness wasn’t total and some UV radiation was still able to reach the Earth’s surface. While photosynthesis was probably seriously impaired for a couple of years, only about 50% of plant taxa became extinct and marine phytoplankton recovered very quickly.

  8. The best estimate now for the C-P Chicxulub extinction event is now 66.05 (+/- 0.10) My.
    The 65.5 Mya number is outdated, circa 2016 or 2017. I forget exactly, or what the ref is.

  9. Here’s another article on the C-P Chicxulub extinction event .

    Apparently, a paleontologist has found a site in North Dakota that marked the farthest extent of the enormous, chaotic wave of water, mud, plant life, marine and land animals created by that event, one that swept across the American continent at hundreds of miles per hour.

    Nothing but a cataclysmic event could have created such a wave, which seems to have utterly destroyed all life in its path over literally millions of square miles.

    So only a few hours separate the North Dakota debris from the impact in Yucatan.

  10. David the abundance of sulphur from gypsum and anhydrite known to exist in surounding formations was prodigious (24% sulph which would become double its mass as SO2 and ~triple its mass as H2SO4 droplets) in the atmosphere. However the even thicker Carbonate formations would volatilize far more CO2 as it is composed of ~40% CO2.

    Given the crater is 75km in radius and is 20km deep, if only 1000m of carb formation were volatilized, that mass of rock is 17 trillion cubic metres, almost 50 trillion tonnes. The Carbon dioxide evolved from only a thousand meters thickness would have been 20 trilion tonnes of CO2, seven times the present content of the atmosphere. Morover, before the impact, CO2 was already 7 times todays CO2 content so it was doubled in one day! And boy did the planet get greened!

    Here is a photo of a redwood chunk from 300m depth in the in the Ekati diamond open pit in Northwest Territories Canada. It seems it erupted in a redwood forest near the present day Arctic circle 53million years ago. The continents had drifted almost to their present location by that time.

    • Gary,

      What chemical reactions are invoked to turn gypsum and so on to H2SO4 drops in the air?
      The energetics favour the other direction, IIRC.
      Geoff S

    • Gary Pearse – September 10, 2019 at 9:12 pm

      Given the crater is 75km in radius and is 20km deep, if only 1000m of carb formation were volatilized, that mass of rock is 17 trillion cubic metres, almost 50 trillion tonnes.

      The Carbon dioxide evolved from only a thousand meters thickness would have been 20 trilion tonnes of CO2, seven times the present content of the atmosphere.

      Morover, before the impact, CO2 was already 7 times todays CO2 content so it was doubled in one day! And boy did the planet get greened!

      Gary, iffen the crater in question is 20,000 meters deep ….. and its contents had all volatilized and forcefully expelled into the atmosphere, …… just how many of those 20,000 meters were “carb formation” meters?

      If all of them were “carb formation” meters …then that would mean that 400 trillion tonnes of CO2, or 140 times the present content of the atmosphere, ….. was ejected into the atmosphere.

      So, iffen before the impact, CO2 was already 7 times todays CO2 content, at 2,870‬ ppm, …… and the asteroid ejected CO2 added another 57,400 ppm, …… the total atmospheric CO2 would have been ‬ 60,270‬ ppm, ….. or 6% of atmospheric gasses (2% greater than tropical H2O vapor),

      Now 6% atmospheric CO2 should show up on a proxy record, …….. somewhere.

      • The entire volume of the crater didn’t vaporize. Most of the 20 km depth was into continental crust (granitic rocks) and the upper mantle. Much of this rock melted and flowed back into the crater within a few minutes.

        In this simulation, an asteroid hits a layered target composed of carbonate platform sediments overlying granitic continental crust and the mantle. On impact, a transient cavity opens up, reaching a maximum depth of 32 kilometers 20 seconds after impact. The crater floor then begins to rise. The maximum cavity volume is generated after 55 seconds while the crater floor continues to rise. The central uplift surpasses the pre-impact target surface 2 minutes after impact and reaches a maximum height of ~15 kilometers at ~3 minutes. As the central uplift collapses, granitic material is spread out over the surface burying the carbonate platform sediments. After ~8 minutes the crater formation process is complete. The final crater has a rim-to-rim diameter of ~160 kilometers; the peak ring, formed by the collapsing central uplift, has a diameter of ~90 kilometers. At depth, the crater collapse process has uplifted the crust/mantle boundary by ~2 kilometers beneath the crater center and created a slight thickening (~1 kilometer) of crustal material 35 kilometers out from the center.

        The crater annealed within a few minutes.

        Green = Cretaceous carbonates and anhydrites.
        Yellow = Continental crust.
        Brown = Mantle.

        The Chicxulub Crater has a peak-ring structure. This means there is a circular uplifted mountainous ring within the crater. As shown schematically here, that peak ring (beige-colored peaks) was covered by impactites (purple). The peak ring also bounded the central impact melt sheet (red) and an overlying layer of impact breccias (purple). Additional impact melt and breccias occurred between the peak ring and crater rim. Impact breccias were also ejected from the crater. The mantle beneath the crater (brown) was uplifted about 1 kilometer. The entire crater was subsequently buried by Tertiary sediments (gray). In 2001-2002, the Chicxulub Scientific Drilling Project drilled through those sediments and the impact sequence in the trough between the peak ring and zone of slumped blocks (called a modification zone) in the outer portion of the crater. That borehole is called Yaxcopoil-1.

        Illustration Credit: David A. Kring, NASA/Univ. Arizona Space Imagery Center

        • David Middleton September 12, 2019 at 12:44 pm

          The entire volume of the crater didn’t vaporize. Most of the 20 km depth was into continental crust (granitic rocks) and the upper mantle. Much of this rock melted and flowed back into the crater within a few minutes.

          So, it appears that you are saying that the asteroid, per se, exploded on contact with the surface, melted all the underneath terra firma except that which contained sulfur and CO2, ….. with the force of the explosion “blowing” everything far out of the cavity and only the liquid rock flowed back in to refill the cavity.


          David M, ….. I am sure you have an excellent explanation as to why the posted diagram of the amazingly created Chicxulub crater underneath the Yucatán Peninsula ……. is far, far vastly different than is this actual picture of Meteor Crater Arizona (Barringer Meteorite Crater).

          Now I would reason that the greater the size of the asteroid, the greater the explosion, …… and the greater the explosion, the greater the created cavity, …… and the greater the explosion the greater the distance that the residue from the cavity is forcefully thrown.

          Note: the Chicxulub “explosion” delivered an estimated energy of 21–921 billion Hiroshima A-bombs. For comparison, this is ~100 million times the energy released by the Tsar Bomba, a thermonuclear device. Ref:

          • Why would anyone think that a 49,000 year old, 1.2 km diameter, 0.2 km deep crater, should look like a 65-66 million year old, 120 km diameter, ~3-4 km deep crater, that has been infilled and buried under 1 km of Cenozoic sedimentary rock?

            Both Barringer and Chicxulub were much deeper at the time of impact, but quickly annealed as melted rock cooled. Barringer has barely been affected by geological processes since it was formed. Chicxulub has been buried by 65 million years of sedimentation.

          • So, it appears that you are saying…

            I said what I said, not whatever it is you think it appears that I said.

            If I didn’t know it would be a total waste of my time, I would post the chemical equations for the oxidation and/or melting of anhydrite, dolomite, calcite and granite, along with the temperatures these things occur, in an effort to explain what would have vaporized and what would have just melted.

            However, I don’t speak faux frontier gibberish. So, most of the time, I have no idea what you are trying to communicate in your mostly unintelligible comments and questions.

          • You are correct, David, …… I apologize, …… I am not sufficiently learned to question anything that you speak or write about the subject matter that was being discussed.

            Like most times hereon, ….. NIH is my “stumbling block”.

            I’ll try not to bother you any further.

  11. Gee mods is there someway for me to get a reprieve. I might need some advice. This is an uncontroversial geological thread and I am a geologist.

    • I doubt it is the Mods, Gary. It’s probably the usual comment software quirks we experience here at WUWT. I very seldom have a post appear immediately after I hit the post key. I usually have to wait until the top of the hour before it shows up.

        • In my all error bounds considered at this point, I still got to say that to me it appears to be not a proper software issue, David… but more like a “hardware” issue…
          aka Anthony’s orthodoxy “protocol” approach to safety… too strict, too straight, too much at this point in time, I think… too orthodox under the consideration.

          And I cold still be incredibly wrong with this one, but just saying… as per 0.0 in naivety.
          Oh well, maybe I should not have mentioned at all.

          Hope there same sense, this makes… 🙂


          • Hardware or software… I’m fairly certain that Gary Pearce’s comments are being intentionally put in moderation.

  12. One thing I noted once, in New South Wales we have thick high-quality Permian coals, that disappear for ~10 millions at the end of the Permian-the swampy plants that produced the coals were all dead, and had to actually re-evolve, and the coals you then get 10 million years later are weak. Right on the P-T boundary, you often get a thin layer of red-beds-which stand out as orange-red sandy sediments, completely unlike what’s before and after, which are devoid of vegetation and indicate hot house conditions; dry, hot, and lacking vegetation. You also get them in South Africa. These mark the extinction, but also a change in climate-from relatively wet to dry and hot.

    Something interesting, as I’ ve seen it in drill core which crosses the coal-rich boundary at the time of the P-T extinction.

    • I spent my college years in the Hartford Basin of the Newark Supergroup, a similar Triassic sequence. Red sandstone (arkose) and diabase (intrusive basalt) sills. Hot, dry, little in the way of life and shallow rift-related basaltic intrusives.

  13. Mount Pinatubo injected about 20 million metric tons of sulfate aerosols into the stratosphere and caused about 0.7 °C of cooling, offsetting over 100 years of Gorebal warming for about three years. Pinatubo also injected about 50 million metric tons of CO2 into the atmosphere and caused no warming.

    You are almost certainly correct that the CO2 from Mt P did not cause any warming. But the statement that Mt P caused no warming is likely incorrect.

    Temperature of Lower Stratosphere ( TLS ) initially rose as aerosols at that height absorbed more sunlight, this corresponded to the much cited cooling of the lower climate system. However, what gets very little coverage is that TLS did not just revert to earlier levels, it fell to a level about 0.5deg C and stayed there. That shows that the stratosphere was more transparent than before the event ( sulphate aerosols destroy ozone, but let’s just blame CFCs ). This also implies a greater amount of solar radiation makes it into the lower atmosphere.

    It becomes clear that at least some of the late 20th c. warming was due to Mt P (1991) and El Chichon (1982) which had similar effects. This is never discussed , only the temporary cooling. Instead this warming is falsely attributed to CO2. That is why climate models fail after the supposed end of volcanic effects around 1995.


    TLS inverted vs SH warming.

  14. Last April Robert DePalma published in PNAS his article on a North Dakota fossil field that was formed less than an hour after the impact. He had been investigating for decades and the astounding results were controversial not in their importance but on their interpretation.

    A few days later The New Yorker run an article on his discovery entitled “The day the dinosaurs died.”
    It is a long article well worth the time for anybody interested in the Late Cretaceous impact. The author, Douglas Preston describes the event as the day the Earth was shot a bullet and almost died.

    Although 75% of species went extinct due to the impact and associated effects, 99.999% of individuals on Earth at the time died due to it. DePalma appears to have found the fossil remains of a few of them.

  15. Great to read and science you can believe in coupled with interesting comments.
    Incidentally, the survival of individual species may perhaps in a few cases have come from just a few lucky individuals – the Antarctic birds comment was instructive – which just happened to be a very fortunate and in a “protected” place and later recolonised. I’m thinking here of the crocodiles which have survived living in tunnels in the Sahara and emerge briefly during a very short rainy season. They’ve been hanging on for a very long time.

  16. “..It has been postulated that the the initial effect of the Chicxulub impact was a sharp rise in temperature associated with the fireball..”

    No s**t? Did they think the fireball was cold?

  17. It must have been a hell of a hit, that fossil formation in North Dakota of dinosaurs who were killed by a huge tidal wave, it traveled hundreds of miles from the impact point.

  18. I saw a documentary on NetFlix about a month ago about the drilling of that core sample. I do not remember the name.

  19. David
    You provide outstanding instruction in geology.
    I have a question.
    I there were two identical such impact craters, would they be called “Equicraters”?
    Just asking.

  20. “Hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.”

    I thought that the crater was miles deep, did they really drill to the bottom? Could there still be an iridium-rich asteroid underneath?

    • The crater was “miles deep” only for a few minutes…

      In this simulation, an asteroid hits a layered target composed of carbonate platform sediments overlying granitic continental crust and the mantle. On impact, a transient cavity opens up, reaching a maximum depth of 32 kilometers 20 seconds after impact. The crater floor then begins to rise. The maximum cavity volume is generated after 55 seconds while the crater floor continues to rise. The central uplift surpasses the pre-impact target surface 2 minutes after impact and reaches a maximum height of ~15 kilometers at ~3 minutes. As the central uplift collapses, granitic material is spread out over the surface burying the carbonate platform sediments. After ~8 minutes the crater formation process is complete. The final crater has a rim-to-rim diameter of ~160 kilometers; the peak ring, formed by the collapsing central uplift, has a diameter of ~90 kilometers. At depth, the crater collapse process has uplifted the crust/mantle boundary by ~2 kilometers beneath the crater center and created a slight thickening (~1 kilometer) of crustal material 35 kilometers out from the center.

      • I don’t want to be nearby when they test THAT model experimentally… Depth of 32 kilometers 20 seconds after impact .. The central uplift .. reaches a maximum height of 15 km at 3 minutes .. That’s still 17 km down. I still don’t believe that they drilled that deep.

        I consider the article an interesting speculation. Error bars on that work must be amazingly long. The global warming is quite a certainty in comparison.

        • They didn’t have to drill very deep. The crater annealed within a few minutes, as shown by the animation. The seismic profile in the post shows the base of the crater and where the core tagged it

  21. I once attended a lecture by Dr. Amy Mainzer, widely recognized (including by me) as the hottest astronomer on Earth. The subject was Near Earth Objects(NEOs), of which the Chicxulub meteorite was definitely an example since it was near enough to actually bury itself in the Earth.

    Dr. Mainzer noted that, in addition to the iridium spike at the K-T boundary, there was a substantial layer of carbon (charcoal) at that boundary. She stated as fact that this was proof that the plant life on Earth all burned as a result of the collision. She went on to assert that this released an enormous amount of CO2 into the atmosphere, causing global warming, which in turn was the cause of the K-T extinction.

    I just about left the lecture at that point, because of the simplicity of the error in that thinking. What was the mechanism for “global warming” causing a mass extinction? It isn’t obvious, or even evident. But if all of the plant life on the surface burned, the food chain would be cut off at the base, and mass extinction would have been inevitable – quickly.

    Nevertheless, I stayed for the remainder of the lecture because, as I mentioned earlier, she is really hot. And yes, I am that shallow.

    • Right. It wasn’t searing heat, a rain of molten rock, wildfires covering thousands or millions of square miles, a mile-high tsunami, anoxic seas, waves of magnitude 11 earthquakes, billions of tons of sulfur released into the atmosphere, producing global smog blocking the sun and cooling the Earth after its superheating. Nope! It was CO2!

  22. An attempt to describe the event and the devastation caused by the ejecta. Some nice experiments used to illustrate the problem, including a high velocity impact cannon and a pizza oven…
    2 hours, but entertaining. They got puppets!


  23. As, far as I can tell, all this brilliant and hipper official orthodox academic attempted explanation of Jurasic extinction, suffers in and by a single concept, or a conceptual condition;


    That extinction event seems to be a result of a non reversible natural condition.

    The one academically considered thus far, does not offer that, and does not qualify as such…
    as non reversible… it, happens to be reversible… over time.

    Oh well, anything could be possible, pink unicorns have already got their own universe and an indisputable reality in what we keep calling science… or modern or post modern science.


    • Before discovery of the iridium layer, there was no good explanation for the end Cretaceous (not Jurassic) mass extinction event, which wiped out a lot more than just non-avian dinosaurs. An impact from space was then a radical idea. The hypothesis was confirmed by discovery of the Yucatan crater.

      • As I commented earlier, I’m hard-pressed to come up with a geological hypothesis that has been so consistently reinforced over time. Every discovery has built upon previous discoveries.

        • Right up there with the once-denigrated “continental drift” and “Missoula floods”.

          For that matter, ice ages were once doubted until repeatedly confirmed. Ditto Milankovitch cycles as an explanation thereof.

          Same goes for the age of the earth.

      • The Cretaceous–Paleogene mass extinction event some 66.5 Ma suddenly wiped-out about 75% of the plant and animal species on Earth. With the exception of some ectothermic species such as the leatherback sea turtle and crocodiles, no tetrapods weighing more than 55 lb survived.

        While the non-avian dinos get top billing, a wide range of species perished in the K–Pg extinction. It also destroyed a plethora of other terrestrial organisms, including some mammals, pterosaurs, birds (aka avian dinosaurs), lizards, insects and plants.

        In the oceans, the end Cretaceous mass extinction killed off plesiosaurs and mosasaurs, giant marine lizards, and devastated fish, sharks, mollusks (especially ammonites, the entire subclass of which went extinct), and many species of plankton.

  24. It does make you wonder though about some breakup into more than one impactor. Earth does not have the gravitation force of a Jupiter but still look at all those barbell meteors out there in observations of the solar system in recent years.

    • Maybe bits or pieces of it landed elsewhere, but it’s clear that an asteroid or other celestial body some seven to 50 miles in diameter, with a mass between 1.0×10^15 and 4.6×10^17 kg slammed into the Yucatan about 66.5 Ma, with serious consequences.

  25. This amateur needs help!
    Does anybody who knows this stuff tell me:
    What does the fossil record show as the KT boundary is approached? Were the Dinosaurs in full bloom, the obvious dominant land vertebra like they say they were? Or , were their numbers decreasing?

  26. The quote below comes from a article in 2010 where 41 experts confirmed that the asteroid killed off the Dinos in a few hours or weeks.

    This is a caption of a picture showing a bright white line as the KT boundary.

    The K-Pg boundary as exposed along the side of Interstate 25 near Raton Pass in southern Colorado. The obvious white layer is the K-Pg ejecta layer, says the University of Texas at Austin. It contains elevated levels of iridium and shocked mineral grains. Pollen and spores from Cretaceous plants are found immediately below this layer but not above it, a pattern that is seen from the southern United States all the way north to the Arctic Ocean. “This direct link between impact ejecta and plant extinction suggests a very strong cause and effect relationship between impact and extinction.”

    My problem. NO mention of dinosaurs fossils. Does anybody know the answer to my question?

  27. Thank you for the references.
    I was hoping that there would be evidence of a thriving dino population below and nada above the KT layer.
    But, let’s forget dinos for a second. How about reptiles and mammals? How close beneath the KT boundary are their fossils found?

    • Mammals and reptiles are also poorly preserved as fossils. Mammal fossils become more abundant and diverse above the K-Pg boundary than below it. But the fossil record isn’t like a census.

    • Dinosaurs are reptiles. I suppose you mean other reptiles.

      As David points out, the places where the Mesozoic/Cenozoic boundary is exposed on land are few. The odds of finding terrestrial tetrapod fossils above and below those scarce outcrops are thus low.

      But please David’s links, especially that from this year, which discovery has previously been cited here. The site in ND contains the jumbled up remains of both marine and terrestrial organisms, assembled by the tsunami which flowed north from the Gulf of Mexico along the remnants of the Western Interior Seaway.

      To wit:

      “This unique, fossilized graveyard — fish stacked one atop another and mixed in with burned tree trunks, conifer branches, dead mammals, mosasaur bones, insects, the partial carcass of a Triceratops, marine microorganisms called dinoflagellates and snail-like marine cephalopods called ammonites — was unearthed by paleontologist Robert DePalma over the past six years in the Hell Creek Formation, not far from Bowman, North Dakota. The evidence confirms a suspicion that nagged at DePalma in his first digging season during the summer of 2013 — that this was a killing field laid down soon after the asteroid impact that eventually led to the extinction of all ground-dwelling dinosaurs. The impact at the end of the Cretaceous Period, the so-called K-T boundary, exterminated 75 percent of life on Earth.”

      Plumage found at the Tanis site could have come from birds, but at least one big feather might be from a non-avian dinosaur.

      • Perhaps more accurate to say seiche than tsunami, as the massive earthquakes produced sloshing. But global tsunamis also radiated out from the impact site.

        • I was thinking in the Western Inland Seaway. It’s uncertain whether or not it was still open to the Gulf of Mexico at he the time of the impact. If it wasn’t open, it would have been a seiche. Either way, it was catastrophic.

Comments are closed.