NEWS NOTES ON SUSTAINABLE WATER RESOURCESChicxulub Crater and Other Impacts https://en.wikipedia.org/wiki/Chicxulub_crater “Th...NEWS NOTES ON SUSTAINABLE WATER RESOURCESChicxulub Crater and Other Impacts https://en.wikipedia.org/wiki/Chicxulub_crater “The Chicxulub crater (/ˈtʃiːkʃʊluːb/; 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-aviandinosaurs.”But there are other impact events that are not as well known, such as the Kiptopeke Impact. See https://pubs.usgs.gov/fs/fs49-98/“A spectacular geological event took place on the Atlantic margin of North America about 35 million years ago in the late part of the Eocene Epoch. Sea level was unusually high everywhere on Earth, and the ancient shoreline of the Virginia region was somewhere in the vicinity of where Richmond is today. Tropical rain forests covered the slopes of the Appalachians. To the east of a narrow coastal plain, a broad, lime (calcium carbonate)-covered continental shelf lay beneath the ocean. Suddenly, with an intense flash of light, that tranquil scene was transformed into a hellish cauldron of mass destruction. From the far reaches of space, a bolide (comet or asteroid), 3-5 kilometers in diameter, swooped through the Earth's atmosphere and blasted an enormous crater into the continental shelf. The crater is now approximately 200 km southeast of Washington, D.C., and is buried 300-500 meters beneath the southern part of Chesapeake Bay and the peninsulas of southeastern Virginia.The entire bolide event, from initial impact to the termination of breccia deposition, lasted only a few hours or days. The crater was then buried by additional sedimentary beds, which accumulated during the following 35 million years.The Chesapeake Bay crater was recently identified by C. Wylie Poag (U.S. Geological Survey, USGS), who has assembled an international team to investigate its characteristics and consequences. Evidence of the crater comes from two sources: (1) cores drilled by the USGS and the Virginia State Water Control Board, and (2) marine seismic-reflection profiles collected by Texaco, Inc., the USGS, and the National Geographic Society.” Coming closer to the present day, there is Meteor Crater in Arizona. Seehttps://en.wikipedia.org/wiki/Meteor_Crater”Meteor Crater is a meteoriteimpact crater approximately 37 miles (60 km) east of Flagstaff and 18 miles (29 km) west of Winslow in the northern Arizona desert of the United States. Because the United States Board on Geographic Names commonly recognizes names of natural features derived from the nearest post office, the feature acquired the name of "Meteor Crater" from the nearby post office named Meteor. The site was formerly known as the Canyon Diablo Crater and fragments of the meteorite are officially called the Canyon Diablo Meteorite. Scientists refer to the crater as Barringer Crater in honor of Daniel Barringer, who was first to suggest that it was produced by meteorite impact. The crater is privately owned by the Barringer family through their Barringer Crater Company, which proclaims it to be the "best preserved meteorite crater on Earth". Despite its importance as a geological site, the crater is not protected as a national monument, a status that would require federal ownership. It was designated a National Natural Landmark in November 1967.” Meteor Crater is about 55,000 years old.In recent historic times, the Tunguska Event of 1908 is significant. See https://en.wikipedia.org/wiki/Tunguska_event“The Tunguska event was a large explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of 30 June 1908 (NS). The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 square kilometres (770 square miles) of forest, and may have caused up to three human casualties. The explosion is generally attributed to the air burst of a meteoroid. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth. The Tunguska event is the largest impact event on Earth in recorded history. Studies have yielded different estimates of the meteoroid's size, on the order of 50 to 190 metres (160 to 620 feet), depending on whether the body entered with a low or high speed.