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peared abruptly from the fossil record at the iridium boundary。 one of the most vigorous opponents was charles officer of dartmouth college。 he insisted that theiridium had been deposited by volcanic action even while conceding in a newspaper interviewthat he had no actual evidence of it。 as late as 1988 more than half of all americanpaleontologists contacted in a survey continued to believe that the extinction of the dinosaurswas in no way related to an asteroid or etary impact。
the one thing that would most obviously support the alvarezes’ theory was the one thingthey didn’t have—an impact site。 enter eugene shoemaker。 shoemaker had an iowaconnection—his daughter…in…law taught at the university of iowa—and he was familiar withthe manson crater from his own studies。 thanks to him； all eyes now turned to iowa。
geology is a profession that varies from place to place。 in iowa； a state that is flat andstratigraphically uneventful； it tends to be paratively serene。 there are no alpine peaks orgrinding glaciers； no great deposits of oil or precious metals； not a hint of a pyroclastic flow。
if you are a geologist employed by the state of iowa； a big part of the work you do is toevaluate manure management plans； which all the state’s “animal confinement operators”—hog farmers to the rest of us—are required to file periodically。 there are fifteen million hogsin iowa； so a lot of manure to manage。 i’m not mocking this at all—it’s vital and enlightenedwork； it keeps iowa’s water clean—but with the best will in the world it’s not exactly dodginglava bombs on mount pinatubo or scrabbling over crevasses on the greenland ice sheet insearch of ancient life…bearing quartzes。 so we may well imagine the flutter of excitement thatswept through the iowa department of natural resources when in the mid…1980s the world’sgeological attention focused on manson and its crater。
trowbridge hall in iowa city is a turn…of…the…century pile of red brick that houses theuniversity of iowa’s earth sciences department and—way up in a kind of garret—thegeologists of the iowa department of natural resources。 no one now can remember quitewhen； still less why； the state geologists were placed in an academic facility； but you get theimpression that the space was conceded grudgingly； for the offices are cramped and low…ceilinged and not very accessible。 when being shown the way； you half expect to be taken outonto a roof ledge and helped in through a window。
ray anderson and brian witzke spend their working lives up here amid disordered heapsof papers； journals； furled charts； and hefty specimen stones。 （geologists are never at a lossfor paperweights。） it’s the kind of space where if you want to find anything—an extra chair； acoffee cup； a ringing telephone—you have to move stacks of documents around。
“suddenly we were at the center of things；” anderson told me； gleaming at the memory ofit； when i met him and witzke in their offices on a dismal； rainy morning in june。 “it was awonderful time。”
i asked them about gene shoemaker； a man who seems to have been universally revered。
“he was just a great guy；” witzke replied without hesitation。 “if it hadn’t been for him； thewhole thing would never have gotten off the ground。 even with his support； it took two yearsto get it up and running。 drilling’s an expensive business—about thirty…five dollars a footback then； more now； and we needed to go down three thousand feet。”
“sometimes more than that；” anderson added。
“sometimes more than that；” witzke agreed。 “and at several locations。 so you’re talking alot of money。 certainly more than our budget would allow。”
so a collaboration was formed between the iowa geological survey and the u。s。
geological survey。
“at least we thought it was a collaboration；” said anderson； producing a small painedsmile。
“it was a real learning curve for us；” witzke went on。 “there was actually quite a lot of badscience going on throughout the period—people rushing in with results that didn’t alwaysstand up to scrutiny。” one of those moments came at the annual meeting of the americangeophysical union in 1985； when glenn izett and c。 l。 pillmore of the u。s。 geologicalsurvey announced that the manson crater was of the right age to have been involved with thedinosaurs’ extinction。 the declaration attracted a good deal of press attention but wasunfortunately premature。 a more careful examination of the data revealed that manson wasnot only too small； but also nine million years too early。
the first anderson or witzke learned of this setback to their careers was when they arrivedat a conference in south dakota and found people ing up to them with sympathetic looksand saying： “we hear you lost your crater。” it was the first they knew that izett and the otherusgs scientists had just announced refined figures revealing that manson couldn’t after allhave been the extinction crater。
“it was pretty stunning；” recalls anderson。 “i mean； we had this thing that was reallyimportant and then suddenly we didn’t have it anymore。 but even worse was the realizationthat the people we thought we’d been collaborating with hadn’t bothered to share with us theirnew findings。”
“why not？”
he shrugged。 “who knows？ anyway； it was a pretty good insight into how unattractivescience can get when you’re playing at a certain level。”
the search moved elsewhere。 by chance in 1990 one of the searchers； alan hildebrand ofthe university of arizona； met a reporter from the houston chronicle who happened to knowabout a large； unexplained ring formation； 120 miles wide and 30 miles deep； under mexico’syucatán peninsula at chicxulub； near the city of progreso； about 600 miles due south of neworleans。 the formation had been found by pemex； the mexican oil pany； in 1952—theyear； coincidentally； that gene shoemaker first visited meteor crater in arizona—but thepany’s geologists had concluded that it was volcanic； in line with the thinking of the day。
hildebrand traveled to the site and decided fairly swiftly that they had their crater。 by early1991 it had been established to nearly everyone’s satisfaction that ch