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Penfield was initially unable to obtain evidence that the geological feature was a crater and gave up his search.Later, through contact with Alan Hildebrand in 1990, Penfield obtained samples that suggested it was an impact feature.
The numerous sinkholes clustered around the trough of the crater suggest a prehistoric oceanic basin in the depression left by the impact.Hildebrand's team tested the samples, which clearly showed shock-metamorphic materials.A team of California researchers including Kevin Pope, Adriana Ocampo, and Charles Duller, surveying regional satellite images in 1996, found a cenote (sinkhole) ring centered on Chicxulub that matched the one Penfield saw earlier; the cenotes were thought to be caused by subsidence of bolide-weakened lithostratigraphy around the impact crater wall.He then obtained a gravity map of the Yucatán made in the 1960s.A decade earlier, the same map suggested an impact feature to contractor Robert Baltosser, but he was forbidden to publicize his conclusion by Pemex corporate policy of the time.Penfield found another arc on the peninsula itself, the ends of which pointed northward.
Comparing the two maps, he found the separate arcs formed a circle, 180 km (110 mi) wide, centered near the Yucatán village Chicxulub; he felt certain the shape had been created by a cataclysmic event in geologic history.
Evidence for the impact origin of the crater includes shocked quartz, a gravity anomaly, and tektites in surrounding areas.
In 2016, a scientific drilling project drilled deep into the peak ring of the impact crater, hundreds of meters below the current sea floor, to obtain rock core samples from the impact itself.
White dots represent water-filled sinkholes (solution-collapse features common in the limestone rocks of the region) called cenotes after the Maya word dzonot.
A dramatic ring of cenotes is associated with the largest peripheral gravity-gradient feature.
Over a decade or longer, sunlight would have been blocked from reaching the surface of the Earth by the dust particles in the atmosphere, cooling the surface dramatically.