He insisted that the iridium had been deposited by volcanic action even while conceding in a newspaper interview that he had no actual evidence of it. As late as 1988 more than half of all American paleontologists contacted in a survey continued to believe that the extinction of the dinosaurs was in no way related to an asteroid or cometary impact.
The one thing that would most obviously support the Alvarezes' theory was the one thing they didn't have—an impact site. Enter Eugene Shoemaker. Shoemaker had an Iowa connection—his daughter-in-law taught at the University of Iowa—and he was familiar with the 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 and stratigraphically uneventful, it tends to be comparatively serene. There are no Alpine peaks or grinding 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 to evaluate 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 hogs in Iowa, so a lot of manure to manage.