Cayley Formation
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The Cayley Formation is a discontinuous unit of plains-forming material on the Moon. It was first recognized in the central near side of the Moon in 1965, by the
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group of the
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. It was previously mapped as part of the
Fra Mauro formation The Fra Mauro formation (or Fra Mauro Highlands) is a Geology of the Moon, formation on the near side of the Moon, near side of Moon, Earth's Moon that served as the landing site for the American Apollo 14 mission in 1971. It is named after th ...
. During the
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era, the formation was mapped in many other parts of the Moon including the far side (e.g., Mendeleev basin.) The description of the formation from the 1967 edition of the Geologic Map of Julius Caesar Quadrangle (LAC-60) of the Moon follows:Morris, E. C.; and Wilhelms, D. E.
Geologic Map of the Julius Caesar Quadrangle of the Moon
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Misc. Geol. Inv. Map 1-510, 1967. https://doi.org/10.3133/i510
:Surface generally flat and smooth. Apparently lacks ridges and rilles. Appears to mantle subjacent terrain; buried (or ghost) craters evident in some areas (3° 30' N., 14° 40' E.).
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intermediate, about the same as that of the Fra Mauro Formation, higher than Procellarum Group. Crater density greater than on the Procellarum Group. Type area is east of the unrelated crater Cayley for which the formation is named; 3 1/2°-4 1/2° N., 15 1/2°-16 1/4° E. The formation was interpreted as: :Volcanic materials; may be ash-flow or ash-fall tuff with intercalated ballistically deposited layers. In the Cayley Formation near Cayley crater, the formation overlies Imbrium sculpture but is embayed by
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material and has a higher crater density than nearby maria. Thus, the Cayley Formation predates the mare but postdates sculpturing by the Imbrian event.''Apollo 16 Preliminary Science Report'', NASA Special Publication 315, 1972. Chapter 29, part B: Cayley Formation Interpreted as Basin Ejecta, by R. E. Eggleton and G. G. Schaber. One of the main objectives of the
Apollo 16 Apollo 16 (April 1627, 1972) was the tenth human spaceflight, crewed mission in the United States Apollo program, Apollo space program, administered by NASA, and the fifth and penultimate to Moon landing, land on the Moon. It was the second o ...
mission to the Moon in 1972 was to obtain samples of the Cayley Formation, and also the adjacent Descartes Formation.''Apollo 16 Preliminary Science Report'', NASA Special Publication 315, 1972. Chapter 1: Apollo 16 Site Selection, by N. W. Hinners. Most scientists predicted that volcanic rocks would be obtained from the Cayley Formation, but the astronauts (
Charles Duke Charles Moss Duke Jr. (born October 3, 1935) is an American former astronaut, United States Air Force (USAF) officer and test pilot, and young Earth creationist. As Lunar Module pilot of Apollo 16 in 1972, he became the tenth and youngest p ...
and John Young) found almost nothing but
breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...
s. The Cayley Formation was heavily sampled at
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, Spook, and North Ray craters, as well as at the Lunar Module (LM) ''Orion'' and geology stations southwest of the LM. The lack of volcanic rocks returned from the Cayley forced a reinterpretation of its origin. The Cayley was reinterpreted to be a fluidized ejecta deposit resulting from the formation of the Imbrium basin or of the Orientale basin, which occurred after the Imbrium basin-forming event.Lunar Light Plains Deposits (Cayley Formation)--A Reinterpretation of Origin. E. C. T. Chao, L. A. Soderblom, J. M. Boyce, Don E. Wilhelms, and Carroll Ann Hodges. Abstracts of papers submitted to the Fourth Lunar Science Conference, March 5–8, 1973. File:A16PSR Figure29-23(b) Descartes Region.png, The Descartes highlands region, with the Apollo 16 landing point near center. Furrows and approximate outline of the two units of the Descartes highlands are indicated. Plains of the Cayley Formation are shaded; craters are shown by hachures. Northwest-southeast trend of the furrows on the western side of the map area is radial to the Imbrium Basin. File:A16PSR Figure29-7 AS16-M-0449.jpg, Ghost craters on the surface of the Cayley Formation in the bottom of
Albategnius Al-Battani (before 858929), archaically Latinization (literature), Latinized as Albategnius, was a Muslim Islamic astronomy, astronomer, astrologer, geographer and Islamic mathematics, mathematician, who lived and worked for most of his life a ...
crater. Albategnius B crater (above center) is approximately 15 km across. Subdued troughs trending north-northwest may be buried Imbrium sculpture. The Cayley Formation may be mantling fresh craters to produce a subdued flatbottomed bowl shape. File:AS16-112-18269 (21497115889).jpg, View of the lunar surface representing the Cayley Formation around the Lunar Module ''Orion'', taken from Station 4 on Stone Mountain south of the landing point.


References

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Splotches and Mounds
Lunar Photo of the Day (LPOD), June 9, 2007, by Chuck Wood. Surface features of the Moon Apollo 16