A Portrait of Jan Smit

by Steve Brusatte

Dino Data is a Dutch dinosaur site, and a wonderful Dutch site at that, but for the last four months I have published portraits of four American paleontologists. Sure, Robert Bakker and Paul Sereno have made a splash in the Netherlands, but it is more than time to write a portrait of a Dutch paleontologist.or should I say \"great Dutch paleontologist?\"

Even if you are not a native Netherlander you may recognize the name Jan Smit. You may remember how he barely lost out to Walter Alvarez in the race to publish the comet dinosaur extinction theory. Or, you may recall the evidence he unearthed in Belize that redefined this theory. No matter what your scientific specialty is Jan Smit is a name you probably recognize. While Smit barely lost out in publishing his theory he has done more, perhaps more than anyone else, to redefine and prove the famed Alvarez theory.

As many a dinosaur fan knows Walter Alvarez and his Nobel Prize winning father Luis Alvarez published a paper entitled \"Extraterrestrial cause for the Cretaceous-Tertiary Extinction,\" in the famed journal Sciene in 1980.

Preceding their paper the Alvarez family spent many summers exploring the wonderful Cretaceous-Tertiary aged outcrops near Gubbio, Italy. Walter Alvarez originally published paleomagnetic material on these outcrops, but came to realize the wonderfully preserved bed of boundary aged clay. He used this clay to prove the now nearly virtually accepted point: a meteor or comet collided with the earth 65 million years ago, and with it came the extinction of the dinosaurs.

When this theory was first published many fellow paleontologists immediately asked, \"if a meteor crashed down to earth, where is the crater?\" Surely, we all know that meteors and comets leave massive craters when they collide with earth. Several of these craters dot the earth today, including a few very famous ones. Craters in Arizona, Canada, and Europe draw large crowds each year, but neither of these craters were dated to 65 million years ago: the age of the K-T extinction. Exactly where was the crater? Luis Alvarez didn\'t quite seem to care.

Walter Alvarez didn\'t lead a massive search and rescue effort to find one. But, Jan Smit did both. He cared, and took this feeling onto paleontology\'s grand stagewhere he played a major role in finding the crater which was produced as a direct result of the infamous K-T impact. Until the time of Smit many paleontologists and geologists thought they knew where the impact occurred-in the sea. \"That is why we don\'t find a crater,\" they explained, \"because the meteor or comet crashed into the water.\" Many believed this assumption, but others wanted more information. \"If the
meteor or comet crashed into the sea, wouldn\'t it have generated a large tsunami? Shouldn\'t we be able to find evidence of this tsunami?\"

Jan Smit was one of these scientists. In the early 1980\'s Washington paleontologist Thor Hansen was attracted to the area along the Brazos River in central Texas. This river is not decorated by many outcrops, but passes through a sandy bed. Hansen dated this bed as K-T in age, but surprisingly, didn\'t cause much excitement in the world of paleontology. But, one scientist who became excited was Jan Smit, who had an odd hunch. This hunch told him that the Brazos River was the key to the mysteries of the where to locate the crater. Smit first traveled to this Brazos River bed in the early 1980\'s, and immediately recognized its significance.

In a 1985 paper co-authored with Ted Romein Smit included this statement about the Brazos, \"This may be the first evidence of impact (?tsunami) triggered sediment.\" After Smit published his paper University of Washington paleontologist Judy Bourgeois followed his lead and traveled to this river bed to study the impact deposits. To her it was clear-only a very large tsunami could cause these sand beds. In 1988 Canadian scientist Alan Hildebrand decided that the Brazos River tsunami was the key in finding the elusive K-T crater.

Just why, you ask? According to Walter Alvarez\'s book on the extinction, \"T. rex and the Crater of Doom,\" \"He knew that the tsunami could only have come from the south of Texas, because that was the direction toward deep water 65 million years ago, just as it is now. He reckoned that the impact site could not have been too distant from Texas, because the Gulf of Mexico is an enclosed body of water, protected from any tsunami that came from far away. Alan (then) focused his attention on the Gulf of Mexico and the Caribbean . \" By the time Hildebrand egan his search Walter Alvarez thought of a new way of proving the theory that the impact occurred in or near the Gulf. \"For some reason, I had never been particularly impressed with what I had heard about the Brazos River, but one day in early 1990 I had a new idea for a way to look for evidence of a tsunaminot by looking for the sedimentary deposits of the tsunami, but by looking for a gap in the sedimentary record due to tsunami erosion. I reasoned that an impact in an ocean would send tsunamis crashing into all the surrounding shorelines, eroding the continental-margin sediment.

After the event was over, deposition would resume, and the result would be an unconformity-a gap in the sedimentary record-with the upper part of the Cretaceous missing, but the very basal Tertiary present. Even if the impact site had been on oceanic crust that had been subducted, tsunami erosion of the surrounding continental margins might reveal where the crater had been,\" Alvarez explained. Once he thought up his brilliant idea Alvarez began to comb through the records of hundreds of oceanic sediment cores taken by the Ocean Drilling Project.

According to the great geologist, \"There was only one place in the world with that kind of a gap in the record-it was the Gulf of Mexico. Suddenly, I started taking Alan Hildebrand\'s ideas very seriously.\" Later Hildebrand got his hands on a group of magnetic maps of the Caribbean sea floor and noticed a large circular pattern of gravity anomalities near the Yucatan. This suggested a buried crater. Hildebrand rushed to meet two local geologists-Antonio Camargo and Glen Penfield- who were experts on this site.

In a captivating moment for paleontology-and science in general-the crater, called by the name Chicxulub, was found to be K-T in age. In a 1991 paper Hildebrand published his findings. According to Alvarez, \"It was a bombshell. The Crater of Doom was found at last!Thor Hansen\'s fossil age, Jan Smit\'s hunch, Jody Bourgeois\'s detailed study, and Alan Hildebrand\'s relentless search had come to fruition.\" Since the discovery of the crater Smit has partaken in two major research projects aimed at proving that the crater is \"The Crater.\" The first project began in February of 1991, and started off with a disappointment.

Alvarez and Smit, who by chance was visiting Alvarez\'s Berkeley at the time, had set out on an expedition to Mexico in hopes of proving that the Chicxulub crater was not only K-T in age, but that it caused tsunamis. The trip started off on a down note, with no major discoveries, but on the last night of the trek Smit and Alvarez laid their eyes on what Alvarez describes as the most beautiful outcrop he has ever seen. Named Arroyo el Mimbral, this outcrop contained alternating beds of rippled sand and fine clay, which was caused by the infamous tsunami, which as Smit proved, really existed.

In 1997 Smit tagged along on a NASA expedition to Belize and Mexico that was, once again, aimed to prove that Chicxulub was the K-T crater. On the expedition Smit\'s team discovered two important new sites which further proved just what happened one fateful day 65 million years ago.

According to expedition co-leader Kevin Pope of Geo Eco Arc Research of California, \"The (Mexico) site contains two layers of material, or ejecta, thrown out by the impact that flowed across the surface like a thick fluid, known as fluidized ejecta lobes. This is the closest surface exposure of ejects to the Chicxulub crater that has yet been found and the best example known on Earth from a really big impact crater.\"

Following the trip to Mexico was a trip to Belize, where Smit and local geologist Brian Holland guided the expedition to a new ejecta site about 290 miles from the rim of the Chicxulub crater. This site in Belize contains tiny spheres of \"altered green glass called tektites. \" These tektites are rocks that have been melted to glass by the severe heat of an impact. Smit noted that these tektites were similar to those found in Haiti and northern Mexico. According to Smit, this finding links the stratigraphy of the Belize sites to the more distant Caribbean and Mexican ejecta sites.
So, like with his research concerning the Arroyo el Mimbral outcrop, Smit further proved that Chicxulub was the crater. Smit, who works at the Free University in Amsterdam, is noted by Alvarez as a K-T expert.

\"Jan has studied more KT boundaries around the world than anyone else.\" With every trip to a KT site Smit takes, history follows. For, without Smit, the current thinking on the dinosaur extinction would be much different. Without Smit, where would dinosaur science be?

• < Prev
• Next >