| • Science | • People | • Locations | • Timeline |
The main evidence is a widespread, thin layer of iridium present in this geological boundary across the world. Iridium is a rare metal on Earth, but abundant in meteorites. It is thought that this impact event may have been partially or wholly responsible for the Cretaceous-Tertiary extinction eventThe Cretaceous-Tertiary (KT) extinction event also known as the KT boundary (from German: , was a period of extremely frequent extinction of species, about 65. 5 million years ago. It corresponds to the end of the Cretaceous period and the beginning of th.
In early 1990Events January January 3 Former leader of Panama Manuel Noriega surrenders to American forces. January 7 The Leaning Tower of Pisa is closed to the public due to safety concerns. January 9 Lt Gen Bazilio Olara Okello The man who led the coup aginst Dr Apo, Alan K. Hildebrand , a graduate student at the University of ArizonaThe University of Arizona is an institution of higher learning located in Tucson, Arizona. Created by the Arizona Territorial Legislature as a land-grant university in 1885, classes met for the first time in 1891 with 32 students. In 2002, total enrollmen, visited a small mountain village named Beloc in HaitiHaiti is a country situated on the western third of the island of Hispaniola in the Caribbean Sea, east of Cuba; the Dominican Republic shares Hispaniola with Haiti. A former French colony, it was one of the first countries of the Americas, after the Unit. He was investigating certain K-TThe Cretaceous-Tertiary (KT) extinction event also known as the KT boundary (from German: , was a period of extremely frequent extinction of species, about 65. 5 million years ago. It corresponds to the end of the Cretaceous period and the beginning of th deposits that include thick, jumbled deposits of coarse rock fragments, which were apparently scoured up from one location and deposited elsewhere by kilometers-high " tsunamis", giant sea waves, that most likely resulted from an Earth impact. Such deposits occur in many locations, but seem to be concentrated in the Caribbean basinOn May 18, 2000, President Clinton signed into law the Trade and Development Act of 2000. This measure includes the U. Caribbean Basin Trade Partnership Act of 2000 (CBTPA) and the Africa Growth and Opportunity Act of 2000 (AGOA) as well as other importan.
Hildebrand found a greenish brown colored clay with an excess of iridium, and containing shocked quartzFor other uses of this word, see Quartz (disambiguation). Milk quartz rock Quartz is the most abundant mineral on Earth (about 12% vol. It has a hexagonal crystal structure made of trigonal-crystallized silica (silicon dioxide, SiO), with a hardness of 7 grains and small beads of weathered glass that appeared to be tektites. He and his faculty adviser William V. Boynton published the results of the research in the scientific press, suggesting not only that the deposits were the result of an Earth impact, but that the impact couldn't have been more than 1,000 kilometers (620 miles) away.
This was particularly puzzling, because no crater of any size was known to exist in the Caribbean basin. Hildebrand and Boynton also reported their findings to an international geological conference, sparking substantial interest.
Evidence pointed to possible crater sites off the north coast of Colombia or near the western tip of Cuba. Then Carlos Byars , a reporter for the Houston Chronicle, contacted Hildebrand and told him that a geophysicist named Glen Penfield had discovered what might be the impact crater in 1978, buried under the northern Yucatan Peninsula.
In that year, Penfield had been working for Petroleos Mexicanos (PEMEX, the Mexican state-owned oil company), as a staff member for an airborne magnetic survey of the Yucatan peninsula. When Penfield examined the survey data, he found buried in the noisy data a huge underground "arc", with its ends pointing south, in the Caribbean off the Yucatan that was inconsistent with what he knew about the region's geology.
Penfield was intrigued, and managed to obtain a gravity map of the Yucatan that had been made in the 1960s and was gathering dust in PEMEX's archives. He found another arc, but this one was on the Yucatan itself, and its ends pointed north. He matched up the two maps and found that the two arcs joined up in a neat circle, 180 kilometers (112 miles) wide, with its center at the village of Puerto Chicxulub.
Penfield was an amateur astronomer and had a good idea of what he was looking at. Although PEMEX would not allow him to release specific data, the company did allow him and a PEMEX official named Antonio Camargo to present their results at a geological conference in 1981. Unfortunately, that particular conference was under-attended in that year, ironically because most geologists were attending a workshop on Earth impacts, and their report attracted very little attention, though it did get back to Byars.
Penfield didn't give up. He knew that PEMEX had drilled exploratory wells in the region in 1951. One of the wells had bored into a thick layer of igneous rock known as " andesite" about 1.3 kilometers (4/5ths of a mile) down. Such a structure could have resulted from the intense heat and pressures of an Earth impact, but at the time of the borings it had been written off as a " volcanic dome ", even though such a feature was out of place in the geology of the region.
Further studies of the archived well cores would have resolved the issue, but unfortunately most of them had been destroyed in a warehouse fire in 1979. Penfield presently flew down to the Yucatan to see if he could find anything out from the " tailing s" left by the wellheads. This idea didn't pan out, and in one case Penfield found himself digging through a communal pigsty that had been set up on a wellhead site, a task he described as "unpleasant and unrewarding."
After Hildebrand got in touch with Penfield, however, the two men were able to locate two separate samples from the wells drilled by PEMEX in 1951. Analysis of the samples clearly showed shock-metamorphic materials. Studies by other geologists of the debris found in Haiti at Beloc also showed it to be clearly the result of an impact.
This research was persuasive, and received a major boost when a team of California researchers, including Kevin O. Pope , Adriana C. Ocampo, and Charles E. Duller , conducted a survey of satellite images of the region. They found that there was a nearly perfect ring of sinkholes centered on Puerto Chicxulub that matched the ring Penfield had found in his data. The sinkholes were likely caused by subsidence of the crater's wall.
This evidence was enough to get most of the geological community on the bandwagon, and further studies have reinforced the consensus. Indeed, some evidence has accumulated that the actual crater is 300 kilometers (186 miles) wide, and the 180 kilometer ring is just an inner wall.
Coordinates of the Crater are N21º 24', W89º 31'