T. Rex and the Crater of Doom the Brazos river that a tsunami has swept across the Gulf of Mexico millions of years earlier. The discovery was made thanks to a graduate student named Alan Hildebrand that notified Alvarez of the evidence of a crater on the Yucatan peninsula, which had never been published in the scientific literature by the Mexican petroleum geologists that had found it. The age of the crater needed to be determined if it was going to be a candidate for the KT boundary impact, but access to the region was limited by the crater being buried over time and the core samples
Chicxulub crater apart. In late 2006, Ken MacLeod, a geology professor from the University of Missouri, completed an analysis of sediment below the ocean's surface, bolstering the single-impact theory. MacLeod conducted his analysis approximately from the Chicxulub crater to control for possible changes in soil composition at the impact site, while still close enough to be affected by the impact. The analysis revealed there was only one layer of impact debris in the sediment, which indicated there was only one impact. Multiple-impact proponents such as Gerta Keller regard the results as "rather hyper-inflated" and do not agree with the conclusion of MacLeod's