Early on in the eighties, as the debate started, Jan Smit established himself an omnipresent and key figure in the revolutionary work on impact and mass extinction across the Cretaceous-Tertiary (KT) boundary. Over the last 30 years, Jan has been (and remains) at the vanguard of all major KT battles, either to support the abruptness of the extinction among planktonic foraminifera in deep sea setting, or as the first to understand the complexity of the Hell Creek KT site in Montana where cross-cutting river channel sedimentation renders the occurrence of the last dinosaur way more complex to interpret than many thought, or to track down the Chicxulub tsunami deposits all around the Gulf of Mexico. Over the years, I have received numerous e-mails from Jan, with a pdf attached, saying, “read this … should we write a comment?” Jan is probably the person who possesses the most global and complete vision of the KT story. First of all, he has seen, understood, and sampled more KT sites around the world, from southern Spain to Mexico and from deep-sea cores to the remote republic of Georgia, than any other KT worker so far. A quick look at his publication record demonstrates also that he contributed to the debate across a very wide range of disciplines, from micropaleontology to sedimentology, and from petrology to geochemistry. Indeed, by nature, working on the Cretaceous-Tertiary boundary requires an interdisciplinary approach and a constant readiness to learn new fields. Whereas some scientists are often unable to fully break away from their core discipline, Jan has been one of the most successful at crossing interdisciplinary boundaries and learning new techniques to answer a question or provide an independent line of evidence to support a point. Although Jan was originally trained as a sedimentary geologist while working on his Ph.D. thesis in southern Spain, he recognized the need for high-resolution micropaleontology and foraminiferal stratigraphy across the boundary. He trained himself and became so good at foraminiferal stratigraphy, that his work is accepted among (most) specialized foraminiferal biostratigraphers.
In the late seventies, as a graduate student, Jan recognized the possibility that impact might have been responsible for the Cretaceous-Tertiary boundary mass extinction. He realized the importance of geochemical analyses, including the potential role of iridium. He arranged for neutron activation work on a suite of samples across the Cretaceous-Tertiary boundary in southern Spain. Most likely, he would have independently discovered the iridium anomaly at about the same time it was found at Berkeley—either slightly before or slightly after—if only his analytical colleague had swiftly provided him with full information on their results. When he learned of the discovery of iridium by the Berkeley group, he graciously treated his own discovery of the iridium peak as a confirmation.
Another key line of evidence in support of the impact story is the wide occurrence of sanidine spherules in the KT clay. Largely through Jan’s work, it was demonstrated that these sanidine spherules originated as droplets of rock vaporized by the impact. They condensed and traveled in ballistic trajectories, eventually falling to the ground or to the seafloor. In the late eighties and early nineties, Jan Smit wrote a series of papers that clarified the formation process of these enigmatic spherules. He advocated that the sanidine resulted from seafloor authigenic alteration of some precursor mineral, which he inferred to have been pyroxene. Later, he confirmed his assumption by finding the mineral still preserved in spherule from the DSDP site 577B in the Pacific Ocean.
During the recognition of the Chicxulub crater, Jan was the leader of the team that located 13 sites in northeastern Mexico, which display remarkable thick clastic deposits right at the KT boundary. He carried out the first detailed sedimentological study that showed these deposits to have resulted from (1) the outrushing tsunami, (2) the collapse of the adjacent continental margin, and (3) posttsunami seiche-like oscillations in the Gulf of Mexico. The presence of impact glass at the base of this unit and the general high-energy aspect of the KT deposition in northeastern Mexico formed convincing lines of evidence to support Chicxulub as the impact crater responsible for the mass extinction.
Over the last 20 years, I carried out frequent field trips with Jan, and I truly appreciate him as a joyful and always positive companion. It is difficult for me to say what I most admire and respect about him. I certainly commend his incredible skills as a field geologist, with a keen eye to see the minute detail that instantly clarifies a complex suite of sediments. I also enjoy his openness and his willingness to unselfishly share his knowledge, ideas, and experience. Also, I praise his global and holistic vision of problems. However, to be frankly honest, I should admit that what I respect the most is his virtuosity––and this is highly heartening after a long, often hot day, taking samples at a sub-cm scale across a difficult-to-reach KT boundary––to always and instantly spot the best local restaurant no matter where he is in the world. Might it be the “cantina economica” in Ciudad Victoria, in the Mexican state of Tamaulipas, with incredible roasted goat meat, or the fancy “gastronomique” French restaurant, hidden in the countryside where we stopped one dark winter evening, dressed in field gear after a long drive across Burgundy, or his own BBQ in the garden of his house at Coldigioco in Italy, Jan never disappointed me in terms of great food and fantastic scientific exchanges and discussions. It is a pleasure to review briefly Jan accomplishments and to see his name added to the list of Barringer medalists. He definitively deserves the honor.
[ This is perhaps a geo-historical or rather a “destiny” picture; It was taken in 1973, Walter and Milly Alvarez were on a trip to southern Spain and encountered a Dutch field party, with a very young Jan Smit (sitting contemplatively on a rock). When they met again at one of the very first KT boundary meetings in Copenhagen in 1979, neither of them recalled this first encounter. ]