The End of the Dinosaurs and the K-T Boundary: Touching the Proof


Unless you’ve been hiding under a rock in Jurassic Park, you’ve heard that 66 million years ago the dinosaurs just disappeared.

After roaming and ruling the planet for 165 million years – Poof! … well maybe it was Boom! … they were gone.

This famous extinction event is recorded in rocks and is called the K-T boundary* (Cretaceous-Tertiary), and if eliminating the dinosaurs wasn’t bad enough, this earth-altering cataclysm also eliminated 75% of ALL animal species on the planet.

And the cause of this near obliteration of life on earth is one of the biggest scientific mysteries of the ages. Over the years scientists, and even non-scientists like cartoonist Gary Larson, have suggested reasons for this mass extinction at the K-T Boundary.

But the two ideas that have gained the most traction are either a prolonged and prodigious series of volcanic eruptions in what is now India, or a Manhattan-size meteorite screaming through space and crashing into the Yucatan Peninsula in Mexico … or a combination of the two.

Scientists can get pretty huffy about pet theories and a healthy debate has continued for the past 40 years while researchers look for definitive proof. But imagine if you could actually see and touch tangible evidence of such an astounding event – walk right up and put your finger on proof that an astoundingly huge asteroid slammed into the earth and finished the dinosaurs.

Well, you can!

On our recent camping trip out west, Terri and I went looking for this mystical place in the extreme southeastern corner of Colorado, and we found it near the small town of Trinidad – the K-T Boundary

Trinidad is relatively unknown, and would qualify as being “in the middle of nowhere.” But it’s on the interstate and halfway between Santa Fe and Denver, so it’s a busy overnight stop for car travelers, most of whom wouldn’t know the K-T Boundary from a K-Cup coffee.

But enthusiastic rockhounds rub their rock hammers with glee when they dream of a trip to the nearby Trinidad Lake State Park: home of rock-solid proof that a meteor impact wiped out the dinosaurs.

The “asteroid theory,” which started all the excitement, originated in the early 1980s with geologist Walter Alvarez and his Nobel prize-winning physicist father Luis. On a field trip to Gubbio, Italy the duo found a thin claystone layer that had abnormally high levels of iridium, which is extremely rare on earth, but is abundant in meteorites.

After age-dating the rock layer, they proposed the theory that 66 million years ago a huge meteor impacted earth, creating a global cloud of dust and rock debris which blocked sunlight for months. Without sunlight, photosynthesis stopped, all vegetation died along with the plant eaters, resulting in wholesale death up and down the food chain. The proof in the fossil record is indisputable (so far anyway): dino bones below the iridium layer, and none above.

So this thin, iridium-rich rock is the holy grail for curious folks looking for answers to the question of dinosaur extinction. And if you want to see it for yourself, all it takes is a pleasant, quarter-mile hike along the Long’s Canyon Trail in Trinidad Lake State Park.


After a bit of a scramble up the hillside, you’ll be standing next to bona fide, world-famous geologic history.

This photo is the money shot of the rock outcrop, and immediately above my finger is the dark gray, iridium-rich claystone that’s so famous. And why is this thin, relatively insignificant looking rock relevant? Because 66 million years ago it was a dust cloud delivering death to most of the life on the planet, and there are few words more significant than “extinction.”

There have been 5 extinction events in earth’s history. And it’s scary to think that each time life on earth … and that’s all life …  was nearly wiped out. Modern humans have been around for considerably less than one million years, but to put the K-T extinction in perspective, the dinosaurs dominated the planet for 165 million years. And the entire species was decimated in what geologists would call an instant.

I’m a self-admitted science nerd, and as a geologist, seeing and touching tangible proof of a global extinction event was not only humbling, awe-inspiring, and thought provoking, it also ticked a big box on my Bucket List. But even if you’re only mildly curious, you’ll never find a more important, easier-to-access scientific site than on this short hike in southern Colorado.

Next, we’ll tell you exactly how to find it.

Happy Trails,

*Like most sciences, geology has esoteric nomenclature that sometimes seems specifically designed for confusion. For the record, the K in K-T stands for Cretaceous. It was named by the Belgian geologist who discovered it, using the German word for chalk which is kreide … hence the K. And to add to the haze, K-T has since been changed to K-Pg, which stands for Cretaceous-Paleogene. But, the boundary has been called K-T for decades so we decided to go with a name everyone recognizes … now even you.

Photo Credits: 1. Fabio pastori  2. Gary Larson  


We're Terri and James Vance - high school sweethearts who went on to international careers and became world nomads. Today, 65 countries later, we're still traveling ... and still in love. Check out Our Story for more of the backstory at

60 thoughts

    1. On your next trip through make a stop. As I said, you’ll never find an important bit of geological history that’s easier to access. I’m surprised that the Trinidad tourist board doesn’t make a bigger deal of it. ~ James

    1. Anne, for Alvarez the iridium and the ability to correlate this thin, and very distinctive layer over such a wide area was key. Over the years other researchers have found it in more and more locations around the globe. ~ James

    1. Leslie, I’m glad you find this interesting: geeks unite!! If your husband has spent much time in the field, he recognizes from the photos how unusual it is to have an important outcrop so easy to access. It was great fun. ~ James

      1. We carted a heavy stone with a Trilobite in it from Morocco (Atlas Mountains). Also brought some geodes from Tunisia and some Jade from China. Love them all.

  1. Now this is a find! How the heck you learned about this is irrelevant . . . the beauty of the adventure is that you did it! Thanks so much for sharing this theory, the geological photos and the resulting deductions. Can’t wait for your next post on how to get there. Even if we don’t go, we’ve got proof that even dinos succumb to something.

    1. Rusha, I spent quite a bit of time in the Rockies in my university days and knew that the K-T boundary had to be there somewhere; it just took a bit of research to find the best place to see it. In fact, I was so charged-up that we structured our entire trip to make it the first stop. Terri said I looked like a kid at Christmas. 🙂 ~ James

    1. Pam, as you can imagine, there’s been a ton of research done on the K-T boundary and the meteor. The computer modeling on the immediate results of the impact are truly fascinating. Most of the projections for temps, pressures, etc are really beyond comprehension. It was not a good day on earth. ~ James

    1. Alison, dinosaurs have gotten incredibly popular, which is a great thing. Anything that gets kids (and grown-up kids) interested in science is a positive. And my old geology professors would be happy to know that I’m using our blog to toot the geological horn. ~ James

    1. Tracey, geologic time is usually measured in million-year increments, and knife-edge events like this are very rare. And having the chance to truly touch the evidence was, as you say, mind-blowing. Nerd that I am, I can’t imagine anyone not being excited. ~ James

    1. GP, that’s good news because there’s a couple of follow-up posts that you should like as well. Thanks to the dinosaurs, paleontologists are probably thinking that they’re finally getting some of the attention they deserve. ~ James

  2. Very cool! I drove right through Trinidad on my last drive from TX to Denver – wish I’d know to stop and take a look at this. And speaking of nerds, I wish I had an uncolored version of that first dino head picture that I could fill in with my special art markers! It’s a beauty (and I don’t even really like dinosaurs)!

    1. Lexie, in our next post I’ll provide very specific instructions for how to find the K-T boundary at Trinidad State Park. It’s the least I can do for the nerdhood. As for color, our graphics department (that would be Terri) found that colorful beauty online somewhere. Of course any colors on dinosaurs are total guesses, but given the incredible variety of species that evolved in 165 M years, why not a few fabulous colors? Stop in Trinidad if you can. If nothing else, it’s a nice hike in a quiet valley. ~ James

  3. This is so cool. Thank you for always sharing and teaching us along the way. Can’t wait for further posts on this subject.

    1. Thanks so much Sue. This was a fun post to write and I’m glad you enjoyed it. Even after all these years this stuff still fascinates me. The trip is winding down and T and I are off to London tomorrow. We have tix to see the Tina Turner show in the West End which should be great. We’ll see you guys soon. Hugs to Bob and the canines. Love, J

  4. Thanks for the geology lesson, James. Apparently, it was much better to be a cockroach than a dinosaur when the great meteorite struck. They are found both below and above the line. 🙂 And I be sure to add Trinidad to my list of places to see. –Curt

    1. Curt, as usual, some of Mr. Darwin’s ideas were at work. It’s not a pretty mental image, but I can imagine the cockroaches lived for quite a long time on the decomposing flesh of all the dead dinosaurs. This also probably applies to small rat-like mammals that are our oldest relatives. Nature finds a way. ~ James

  5. Very interesting read James thanks. You need to come look over my rock garden again and tell me more about them. Love J&D

    1. That’s a deal Joyce. Before I visit next time I’ll have a look at the local geology and see what that means at Chez Hood. T and I are doing well and hope things are good with you two. Love, JH

  6. A very interesting read. I am now watching documentaries about the other mass extinctions and find it extremely fascinating. Hope the next one is not too soon. 😀

    1. Thanks for the comment Camila and for dropping by the blog. Everyone has heard of the demise of the dinosaurs, but most people know nothing about the other 4 extinctions. Kudos to you for your interest in a topic that most people miss. If you want a detailed picture of the 5 extinctions check out the book “The Ends of the World” by Peter Brannen. (I’ll talk a bit about this book in my next post.) The author is a journalist rather than geologist, so his explanations are written with the general public in mind. ~James

  7. James that is fascinating and I will be sure to have Dave read this too. I think he shares your love of the rocks and the mysteries they hold. Now tell me why is this such a little known place? With your description it would seem that this would be a huge point of interest.

    1. Sue, if you look at this formation and contact, it looks similar to any of the other gazillion rocks in Colorado. And ultimately, one must know the backstory to truly appreciate the significance. I’m biased of course, but like you, I think these guys are sitting on a gold mine. And believe me, after visiting the little town of Trinidad, I know it could use a bit of a boost to the local economy. They just need a geologist on the city council 🙂 ~James

    1. Thanks for the comment Michelle and for dropping by the blog. The mention of geology usually gets a big Ugg! from folks, but I maintain that if it’s explained properly, it can be fascinating. Of course, this topic gets a helping hand from the endlessly interesting dinosaurs. ~James

  8. Thanks for sharing your well-researched field trip summary, James. As a geologist like you, I find that understanding the Earth if best achieved by picking up rocks and climbing on landforms. Your experience at the K-T boundary is a prime example and is an exciting new addition to my geological bucket list.

    1. Joe, part of my university studies was a summer course mapping field geology, which luckily for me, meant two months sleeping in a tent in the mountains outside Crested Butte, Colorado in a camp with no electricity or running water. It seemed rugged at the time, but looking back, I wouldn’t have missed it. The experience was a life-changer which instilled in me a love of the outdoors, camping, and geology that I carry with me today. And my recent trip through the Rockies and Colorado Plateau brought it all back. I hadn’t poked around outcrops and scrambled up rocky hills in a while, and I had forgotten how much fun it is. As a geolgist, I’m sure you can relate.

      The K-T boundary outside Trinidad is super easy to access, and in fact, if you look around it’s evident all over this lovely little valley. You’ll be glad you made the effort. And BTW, my next post provides details on how to get there and there’s a link to your post on Chixulub. I’ll let you know when it posts. ~James

      1. I can certainly relate, James. Geologic field mapping has to be one of the most challenging things I have ever done. Scrambling up steep rocky terrain, making precise measurements, and trying to stay hydrated, while formulating and continually revising a hypothesis of what happened millions of years ago is a true physical and mental test. I am very excited to hear that you will be doing another post on the Trinidad K-T boundary, and pleased that I could add a little something to it. ~Joe

    1. Henry, all the global-warming naysayers who believe that it’s all overblown fiction need to spend some time with a geologist who can show them the fossil record, earth’s history of extinction events, and explain the carbon cycle. Humbling indeed! ~James

    1. As a species, Homo Sapiens is certainly unique Carol, as is our penchant for damaging our environment. Over time, the earth always finds a balance, but at what cost to life? I’m glad you enjoyed the post. ~James

  9. James, Very interesting article and trip. I think we humans should cry “Happy extinction dinosaurs!” That extinction event opened up an ecological niche for mammals, and, then, respectfully for apes and humans.
    Also, I recently came across several interesting articles about birds with beaks [1,2]. Birds with beaks are descendants of flying dinosaurs, who lose their teeth and develop beaks. During the global multi-year winter in an aftermath of asteroid catastrophe beaks proved to be a big advantage. Those birds were able to survive on seeds and nuts. On a humorous side, I would say that thought that pelicans look like flying dinosaurs, but I’m surprised to know that twitters are descendants of dinosaurs too.

    1. Thanks for the comment Victor and for dropping by the blog. I’ve been doing quite a bit of reading about the 5 extinction events, and the evolutionary fallout from each one has been interesting. If you haven’t read “The Ends of the World” by Peter Brannen you should check it out. It covers the extinction events in detail and is very informative reading. Delving into the deep time of earth’s history is humbling to say the least.

      Thanks for a great comment that really adds interest to the post, and also for the links. Best of luck with the new book. ~James

  10. James,

    Love the article. I have been indulging in my love of history recently and spent a lot of time reading on meteor impacts and the K-T Boundary. I decided I want to go somewhere I can see and touch this event in history, because of this article, I have a starting point. Do you know of anywhere else I can explore the K-T Boundary in person? I live in California.

    1. Thanks for the comment and for dropping by the blog. The KT Boundary is visible in a number of places in the Rockies, and probably in your area as well. The main problems when looking for it is knowing exactly where it is (geographically and in the rock column) and how to access it. If it’s on private land, that presents a problem for permission etc. Also, unless you’re a geologist (and even if you are a geologist), it can take a good amount of research to locate exactly where it is. This is the great advantage of the sight in the State Park in southern Colorado. It’s on public lands, is well marked, and has excellent and easy access.

      If you can’t make it to Colorado, my suggestion is to google “KT boundary in California” and follow threads through the forums. There must be a few geeks like us in your area that have sought it out and are willing to spend the time and effort to find it. Good luck and Happy New Year. ~James

  11. I was getting ready to write an article on this place as I visited it last October. I agree that it is very difficult to find. There are no directions. I drove and drove on the opposite end of the park. I spent the night in Trinidad and came back the next morning to find it on the other side that was a good drive away. The back road can be very tricky too as there is that one place that fools you into thinking that is it beside the road.

    1. Thanks for the comment Mick and for dropping by the blog. Knowing that this contact wasn’t easy to find, I did a bit of research in advance and I stopped by the Ranger’s office before I tried to find it. With this prep, I still made a wrong turn. Therefore, I thought that it would be helpful to include specific directions in the post. It’s pretty funny that the signage is great once you get to the parking lot. Anyway, it was great to see it and it’s too bad it doesn’t get more attention. I guess it’s just down to nerds like us. 🙂 ~James

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