Crater Science Reaches New Depths at Chicxulub, Ground Zero for the End of the Dinosaurs

If there was ever any doubt whether an asteroid impact killed off the dinosaurs, field scientists continue to bring back proof from ongoing research in the Gulf of Mexico.
Last week, geologists working in the Yucatán Peninsula reached a major milestone in an offshore drilling project of the Chicxulub Crater, now known to be the remnant of a 66-million-year-old collision of a gargantuan asteroid into the Earth’s surface. Reaching a depth of 670 meters (2,198 feet) in the crater’s peak ring for the first time, the scientists brought up core samples of the original granite bedrock that occurred as a result of this Earth-shattering impact.

Discovered in 1978 by geophysicists Antonio Camargo and Glen Penfield, the crater has been the subject of study and controversy for some time, but this is the first time scientists have dug this deep offshore, into the inner ring of the double-ringed crater. From the core samples, taken from below 66 million years of sediment piled onto the original molten rock formed at the time of the impact, paleontologists now have a completely new data set to study the earliest moments of Earth after the Cretaceous.



With this evidence, we can now put to rest a point of contention regarding the exact border between the Cretaceous and the next age in the life of the Earth, the Paleogene, known as the K-Pg boundary. Prior to this project, paleontologists defined the K-Pg boundary with the appearance of foraminifera, fossils of small shelled creatures. In a sense, the drilling project took science back in time through rock layers never before investigated and passed the K-Pg boundary at ground zero. Because this layer of ancient rock is so thick and and so unique, the drilling team is considering re-naming it the “event layer.”

This news highlights a great number of phenomena in both natural history and astrophyics. Astronomers have studied peak rings in craters on the moon, Mars and Mercury, but never before on our own planet. The Chicxulub now offers a local opportunity to study this type of supermassive impact.

Apparently, peak rings form in a matter of minutes when an asteroid is so big, its impact liquefies rock, causing the center of the crater, while it’s in motion, to splash upward in a cone shape like a drop of water into a filled sink. This molten rock creates a distinct layer of minerals that only form from asteroid collisions. As the team continues to bore deeper, now working more slowly to study this unique type of rock, they will search for rock layers “out of order,” testing a proposed model for this type of impact. Theories state when these impacts occur, older rock layers are tossed above younger rock layers.



The discovery of Chicxulub is a fascinating story in itself, and shows how difficult this thing was to find. Essentially, the crater is so old, the only evidence of it is a trough that forms a faint semi-circle on the western portion of the Yucatán Peninsula and a system of thousands of cenotes, sinkholes formed as a result of the impact. (We’re still unable to explain why.)

Prospecting for oil drilling sites for the Mexican oil company Petróleos Mexicanos (Pemex), Penfield noticed a huge underwater arc 40 miles across in his geophysical data. He found another arc on land years later. Penmex suppressed specific data to the public, but allowed Penfield and Camargo to present the findings at the Society of Exploration Geophysicists conference in 1981, which was poorly attended.

In 1980, unaware of Penfield’s discovery, Alan R. Hildebrand, a graduate student at the University of Arizona, published the first paper proposing the Earth-impact theory and was searching for a probable crater. He and his team found evidence of an impact in shocked quartz, a type of deformed quartz created by intense pressure and limited temperature (the conditions of an impact crater), and tektites, beads of glass shaped like drops of water that form when molten rock is ejected into the atmosphere. Both of these materials occur in large deposits in the Caribbean basin.



Carlos Byars, reporting for the Houston Chronicle in 1990, connected the dots between Hildebrand’s theory and Penfield’s discovery, and Hildebrand and Penfield obtained Penmex drill samples stored in New Orleans for Hildebrand’s team to study. The samples matched Hildebrand’s theories.

Further research into the crater in the late 1990s using gravitational anomaly imaging showed the crater is a system of two concentric circles, the outer circle measuring 190 miles in diameter, nearly five times the diameter of the inner circle.

Personally, as a Texan, a Houstonian and a dinosaur nerd, I take pride in these developments. 1. The Chicxulub crater was discovered by a Mexican oil company. 2. A Houston reporter identified the crater as the one that killed the dinosaurs. Two points for Texas, a state steeped in petroleum science and Mexican culture.

For a grandiose, and slightly terrifying, example of how an asteroid impact can change the face of the Earth (the Chicxulub crater was created by a much smaller asteroid), watch this Discovery Channel simulation set to Pink Floyd’s “Us and Them.”

If All the Dinos Died on One Terrible Weekend – Where are All the Bodies?

Creative Commons License photo credit: goldenrectangle

According to the Impact Theory, a rock from space smashed into the earth, threw up a huge dust cloud, chilled the atmosphere and sent down acid rain.  All the dinosaurs died immediately all over the globe or in a week or so.

So….where are the bodies of the victims?

Probability of Becoming a Fossil: 0%     or    100%

If you die on a high plateau or a grassy meadow or on the average forest floor, far from the influence of river floods, your bones will get chewed, cracked, smashed and digested by scavengers. The remnants will get dried up and will flake away to nothing under the sun. Or, if the ground is wet, worms and grubs and fungi will destroy your osseous remnants.

That happens to most dead bodies, most spots, most of the time. Or…

What if you’re lucky enough to die in a depositional basin, where yearly floods bring in layers of sand, silt and mud, and where lake bottoms accumulate blankets of sediment all the time. A place where huge sand bars develop in streams and rivers….

….then the possibility that some of your bones will get buried and fossilized rises to close to 100%.

Dino Extinction Supposedly Hit While Montana Was Getting Sediment
At the time of the Great Dino Die-Off, no sediment was being laid down in most places in the world. But in Montana’s Cretaceous coal fields, there were many swampy lakes and sluggish rivers, locales where mud and sand was being carried in. This depositional activity seems to have continued right through the end of the Cretaceous and beginning of the next Period, the Tertiary (“Age of Mammals”).

In fact, field geologists have a hard time telling where the Cretaceous mud ends and rhe Tertiary mud begins.

Creative Commons License photo credit: etee

If the Impact Theory is right, millions of Triceratops carcasses littered the landscape. Tens of millions of duck-bill dino bones also covered the ground. And….there were no big scavengers to crack the bones. The average dino body would last far longer than usual. Some of the impact victims should have had a high probability of being buried in the mud at the Impact Layer, the sand and silt and mud deposited right after the rock from the sky struck.

Total number of dino bones found right at the Impact Layer – 00.00.

That’s  one reason why I am an Impact Skeptic. You have to do some special pleading to explain the lack of dino bones at the impact layer. You could argue that soil acid dissolved the bones. Or that for a hundred years there was no new mud, no new sand, no new silt.

Could be.

Still, I like to begin with a geological peshat (first impression): When I scan the actual facts on the ground, there is no evidence whatever of a sudden massive death of dinosaurian multitudes at the Impact Layer.

I dinosauri a Cremona
Creative Commons License photo credit: Simone Ramella

Evidence for a Long, Slow Disaster
There are clues that indicate the dino ecosystem was deteriorating long before the impact. The diversity among big, multi-ton dinos went way down about 5 to 10 million years before the end. In the Latest Cretaceous (Lancian Age) in most places in Montana, there are only two common big dinos – either Triceratops or the duckbill Edmontosaurus. It was a dino-monoculture.  At 76 million years ago diversity was much higher.

Serial Killer in Deep Time
The biggest reason I’m a skeptic is the victim profile. When the dinos finally went extinct, salamanders, frogs, pond turtles, river gators all survived and thrived. So did most small terrestrial species. That pattern holds for six other mass extinctions – beginning at 285 million ears ago, long before the first dino. And the pattern is obvious in the last extinction at the end of the Ice Age, 11,000 years ago.

Impact Theory Fails to Predict the Correct Victim Profile
Sudden chill and acid rain will wipe out salamander-oids and frog-oids and turtle-oids. And hit big, active animals far less severely.

The wrong animals died.

Read about my dinosaur extinction theory in an early blog post.