[Q]: Found the following article online, use it to answer the question: What piece of evidence found at the impact origin of the crater was a gravity anomaly?  The Chicxulub crater (; Mayan: [tʃʼikʃuluɓ]) is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. It was formed by a large asteroid or comet about 11 to 81 kilometres (6.8 to 50.3 miles) in diameter, the Chicxulub impactor, striking the Earth. The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (K–Pg boundary), slightly less than 66 million years ago, and a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth became extinct, including all non-avian dinosaurs. The crater is estimated to be 150 kilometres (93 miles) in diameter and 20 km (12 mi) in depth, well into the continental crust of the region of about 10–30 km (6.2–18.6 mi) depth. It is the second largest confirmed impact structure on Earth and the only one whose peak ring is intact and directly accessible for scientific research.The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán during the late 1970s. 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. 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. The discoveries were widely seen as confirming current theories related to both the crater impact and its effects.
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[A]: shocked quartz


[Q]: Found the following article online, use it to answer the question: What is the last name of the person who obtained his doctorate from UCL before taking on a position at the National Museum of Wales?  Sir Robert Eric Mortimer Wheeler (10 September 1890 – 22 July 1976) was a British archaeologist and officer in the British Army. Over the course of his career, he served as Director of both the National Museum of Wales and London Museum, Director-General of the Archaeological Survey of India, and the founder and Honorary Director of the Institute of Archaeology in London, in addition to writing twenty-four books on archaeological subjects. Born in Glasgow to a middle-class family, Wheeler was raised largely in Yorkshire before relocating to London in his teenage years. After studying classics at University College London (UCL), he began working professionally in archaeology, specialising in the Romano-British period. During World War I he volunteered for service in the Royal Artillery, being stationed on the Western Front, where he rose to the rank of major and was awarded the Military Cross. Returning to Britain, he obtained his doctorate from UCL before taking on a position at the National Museum of Wales, first as Keeper of Archaeology and then as Director, during which time he oversaw excavation at the Roman forts of Segontium, Y Gaer, and Isca Augusta with the aid of his first wife, Tessa Wheeler. Influenced by the archaeologist Augustus Pitt Rivers, Wheeler argued that excavation and the recording of stratigraphic context required an increasingly scientific and methodical approach, developing the "Wheeler method". In 1926, he was appointed Keeper of the London Museum; there, he oversaw a reorganisation of the collection, successfully lobbied for increased funding, and began lecturing at UCL. In 1934, he established the Institute of Archaeology as part of the federal University of London, adopting the position of Honorary Director. In this period, he oversaw excavations of the Roman sites at Lydney Park and Verulamium and the Iron Age hill fort of Maiden Castle. During World War II, he re-joined the Armed Forces and rose to the rank of brigadier, serving in the North African Campaign and then the Allied...
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[A]: Wheeler


[Q]: Found the following article online, use it to answer the question: What genres are defined chiefly by lyrical focus?  The term "Viking metal" has sometimes been used as a nickname for the 1990s Norwegian black metal scene, which was "noisy, chaotic, and often augmented by sorrowful keyboard melodies". It has also been variously described as a subgenre of black metal, albeit one that abandoned black metal's Satanic imagery, "slow black metal" with influences from Nordic folk music, straddling black metal and folk metal almost equally, or running the gamut from "folk to black to death metal". Typically, Viking metal artists rely extensively on keyboards, which are often played at a "swift, galloping pace". These artists often add "local cultural flourishes" such as traditional instruments and ethnic melodies. It is similar to folk metal, and is sometimes categorized as such, but it uses folk instruments less extensively. For vocals, Viking metal incorporates both singing and the typical black metal screams and growls. Overall, Viking metal is hard to define since, apart from certain elements like anthem-like choruses, it is not based entirely on musical features and overlaps with other metal genres, with origins in black and death metal Some bands, such as Unleashed and Amon Amarth, play death metal, but incorporate Viking themes and thus are labeled as part of the genre. Generally, Viking metal is defined more by its thematic material and imagery than musical qualities. Rather than being a mock-up of medieval music, "it is in the band names, album titles, artwork of album covers and, especially, in the song lyrics that Viking themes are so evident." Viking metal, and the closely related style pagan metal, is more of a term or "etiquette" than a musical style. Since they are defined chiefly by lyrical focus, any musical categorizations of these two styles is controversial. Thus, Viking metal is more of a cross-genre term than a descriptor of a certain sound. Ashby and Schofield write that "The term 'Viking metal' is one of many that falls within a complex web of genres and subgenres, the precise form of which is constantly...
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[A]:
Viking metal