Chesapeake Bay impact crater

Coordinates: 37°17′N 76°1′W / 37.283°N 76.017°W / 37.283; -76.017
Source: Wikipedia, the free encyclopedia.
Chesapeake Bay impact crater
Location of impact site in relation to North America
Impact crater/structure
ConfidenceConfirmed
Diameter53 miles (85 km)
Depth0.81 miles (1.3 km)
Impactor diameter1.9 miles (3 km)
Age35.5 ± 0.3 million
ExposedNo
DrilledYes
Bolide typeL chondrite[1]
Location
LocationChesapeake Bay
Coordinates37°17′N 76°1′W / 37.283°N 76.017°W / 37.283; -76.017[2]
CountryUnited States
StateVirginia
MunicipalityCape Charles
Impact location is located in Virginia
Impact location
Impact location
Location of impact site in Virginia
AccessU.S. Route 13 to S.R. 184

The Chesapeake Bay impact crater is a buried impact crater, located beneath the mouth of Chesapeake Bay, United States. It was formed by a bolide that struck the eastern shore of North America about 35.5 ± 0.3 million years ago, in the late Eocene epoch. It is one of the best-preserved "wet-target" impact craters in the world.[3]

Continued slumping of sediments over the rubble of the crater has helped shape the Chesapeake Bay.

Formation and aftermath

During the warm late

tidewater region of Virginia lay in the coastal shallows. The shore of eastern North America, about where Richmond, Virginia is today, was covered with thick tropical rainforest, and the waters of the gently sloping continental shelf were rich with marine life that was depositing dense layers of lime from their microscopic shells.[citation needed
]

Boundaries of the crater.

The bolide made impact at a speed of approximately 17.8 kilometers per second (11.1 miles per second),

peak ring around it. The deep crater, 38 km (24 mi) across, is surrounded by a flat-floored terrace-like ring trough with an outer edge of collapsed blocks forming ring faults.[citation needed
]

The entire circular crater is about 85 km (53 mi) in diameter and 1.3 km (1,300 m; 0.81 mi; 4,300 ft) deep, an area twice the size of Rhode Island, and nearly as deep as the Grand Canyon. However, numerical modeling techniques by Collins et al. indicate that the post-impact diameter was likely to have been around 40 km (25 mi), rather than the observed 85 km (53 mi).[4]

The surrounding region suffered massive devastation.

atmosphere for hundreds of miles along the East Coast." An enormous megatsunami engulfed the land and possibly even reached the Blue Ridge Mountains.[5] The sedimentary walls of the crater progressively slumped in, widened the crater, and formed a layer of huge blocks on the floor of the ring-like trough. The slump blocks were then covered with the rubble or breccia. The entire bolide event, from initial impact to the termination of breccia deposition, lasted only a few hours or days. In the perspective of geological time, the 1.2 km (0.75 mi) breccia was an instantaneous deposit. The crater was then buried by additional sedimentary beds that have accumulated during the 35 million years following the impact.[citation needed
]

The impact has been identified as the source of the North American tektite field, namely the Georgiaite and Bediasite fields.[6]

Discovery

Profile view of the crater

It was not until 1983 that evidence of a large impact crater was found, buried beneath the lower part of the Chesapeake Bay and its surrounding peninsulas. The first hint was an 8-inch-thick (20 cm) layer of ejecta found in a drilling core taken off Atlantic City, New Jersey, about 170 miles (274 km) to the north. The layer contained the fused glass beads called tektites and shocked quartz grains that are unmistakable signs of a bolide impact.

In 1993, data from oil exploration revealed the extent of the crater.[7]

Effects on local rivers

The continual

groundwater contamination.[8]

See also

References

  1. ISSN 0012-821X
    .
  2. ^ "Chesapeake Bay". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 15 September 2019.
  3. ^ "Chesapeake Bay impact structure: Morphology, crater fill, and relevance for impact structures on Mars". USGS. United States Geological Survey. 2006. Retrieved 5 March 2019.
  4. ^
    doi:10.1130/G21854.1
    .
  5. ^ Dell'Amore, Christine (2013-11-21). ""Mind-Blowing" Discovery: Oldest Body of Seawater Found in Giant Crater". National Geographic. National Geographic Society. Archived from the original on 2013-11-21. Retrieved 2015-07-01.
  6. S2CID 128672140
    .
  7. ISBN 978-3-642-62347-9. Archived from the original
    on 9 October 2016. Retrieved 7 October 2016.
  8. S2CID 1735841
    .

Bibliography
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