In structural geology, a roof pendant, also known as a pendant, is a mass of country rock that projects downward into and is entirely surrounded by an igneous intrusion such as a batholith or other pluton. In lay terminology sometimes "rock hat" is used. A roof pendant is an erosional remnant that was created by the removal of the overlying country rock that formed the roof of the igneous intrusion that encloses it. If this downward protruding mass of roof rock still has a connection to the main, surrounding mass of country rock, they are known by structural geologists as either ''septa'' or ''screens.''U.S. Bureau of Mines Staff (1996) ''Dictionary of Mining, Mineral, & Related Terms.'' Report SP-96-1, U.S. Department of Interior, U.S. Bureau of Mines, Washington, D.C.Neuendorf, KKE, JP Mehl, Jr., and JA Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Best, MG (2003) ''Igneous and metamorphic petrology, 2nd ed.'' Blackwell Science Ltd., New York, New York. 729 pp. Roof pendants typically have been strongly

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

through the processes of

contact metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of che ...

.Bucher, K, and R Grapes (2011) ''Petrogenesis of Metamorphic Rocks.'' Springer, New York, New York. 428 pp. A classic, well-documented example of a roof pendant is the strata that comprise

Mount Morrison According to USGS GNIS, Mount Morrison may refer to one of four possible peaks in the United States: It can also refer to: * Mount Morrison in the Lost River Range of Idaho. * One of two mountains in Antarctica, in Enderby Land and Victoria L ...

within the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

Mono Mono may refer to: Common meanings * Infectious mononucleosis, "the kissing disease" * Monaural, monophonic sound reproduction, often shortened to mono * Mono-, a numerical prefix representing anything single Music Performers * Mono (Japanese b ...

and Fresno counties, California. It lies midway between

Mono Lake Mono Lake ( ) is a saline soda lake in Mono County, California, formed at least 760,000 years ago as a terminal lake in an endorheic basin. The lack of an outlet causes high levels of salts to accumulate in the lake which make its water alk ...

on the north and

Bishop, California Bishop (formerly Bishop Creek) is a city in California, United States. It is the largest populated place and only incorporated city in Inyo County. Bishop is located near the northern end of the Owens Valley, at an elevation of . The city was ...

, on the south. Mount Morrison consists of a roof pendant that underlies an area of . This roof pendant consists of a 15,000 m- (50,000 ft-) thick sequence of complexly folded and faulted meta

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

strata and meta

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

strata. The eastern two-thirds of this roof pendant consists of

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

and Pennsylvanian to

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

metasedimentary strata. Metavolcanic rocks of

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

age comprise the western third of the roof pendant. Mesozoic

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

rocks enclose and intrude the pendant rocks. These granitic rocks consist predominantly of

quartz monzonite Quartz monzonite is an intrusive, felsic, igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. It is typically a light colored phaneritic (coarse-grained) to porphyritic granitic rock. The plagiocl ...

and

granodiorite Granodiorite () is a coarse-grained ( phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gr ...

with local, minor, scattered bodies of granite,

aplite Aplite () is an intrusive igneous rock in which the mineral composition is the same as granite, but in which the grains are much finer, under 1 mm across. Quartz and feldspar are the dominant minerals. The term ''aplite'' or ''aplitic'' ...

diorite Diorite ( ) is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-sili ...

and

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...

. These pendants are part of a discontinuous, -long, northwest-trending belt of roof pendants that are preserved within the granitic plutons of Sierra Nevada.Greene, DC, and CH Stevens (1999) ''Stratigraphy, depositional history, and tectonic evolution of Paleozoic continental-margin rocks in roof pendants of the eastern Sierra Nevada, California.'' Geological Society of America Bulletin. 111(6):919-933.Greene, DC, and CH Stevens (2002
''Geologic Map of Paleozoic Rocks in the Mount Morrison Pendant, Eastern Sierra Nevada.''
California Map Sheet no 53. California Division of Mines and Geology, Sacramento, California.Rinehart, CD, and DC Ross (1964
''Geology and mineral deposits of the Mount Morrison quadrangle, Sierra Nevada, California.''
Professional Paper no. 385. United States Geological Survey, Reston, Virginia. 106 pp.Russell, S, and W Nokleberg (1977) ''Superimposition and timing of deformations in the Mount Morrison roof pendant and in the central sierra Nevada, California.'' Geological Society of America Bulletin. 88(3):335-345.

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