Contour lines in gravity data form concentric arcs to the southeast of the impact site, but to the northwest some contours fan outwards. This mirrors the pattern of debris seen around asymmetric craters on the Moon. Schultz and D'Hondt also note that quartz crystals containing shock flaws that are indicative of asteroid impacts, found in sediments dating to 65 million years ago, tend to be larger in North America than in Europe and the Pacific. Larger fragments fall to Earth first, which fits with the idea that debris was scattered to the northwest of the impact zone. Schultz adds that the discovery of what seems to be a piece of the killer asteroid earlier this year fits this pattern, because the pebble came from a seabed core in the North Pacific, along the path of the debris.
Some scientists doubt that it is possible to determine the angle of impact, however.
Richard Grieve of the Geological Survey of Canada in Ottawa thinks that the gravity contours could reflect irregularities that were present before the asteroid hit. He adds that the shocked quartz crystals are not conclusive, because no one has analysed similar crystals from South America. But D'Hondt also points to pollen data. These show that ferns suddenly proliferated just after the impact, presumably after spores colonised newly exposed ground. For me, this is the compelling thing,' says D'Hondt.