Butcher Ridge () is a large, mainly ice-free ridge near the polar plateau in the west part of the

Cook Mountains The Cook Mountains is a group of mountains bounded by the Mulock and Darwin glaciers in Antarctica. Parts of the group were first viewed from the Ross Ice Shelf by the British National Antarctic Expedition (1901–04). Additional portions of th ...

. The ridge is in the form of an arc, extending northwest from

Mount Ayres The Cook Mountains is a group of mountains bounded by the Mulock and Darwin glaciers in Antarctica. Parts of the group were first viewed from the Ross Ice Shelf by the British National Antarctic Expedition (1901–04). Additional portions of th ...

.Faure, G., and Mensing, T. M., 2010. ''The Transantarctic Mountains Rocks, Ice, Meteorites and Water.'' Germany, Heidelberg, Springer Dordrecht. 804 pp. The Ridge peaks at 2,003 meters (6,572 feet). It was named by the

Advisory Committee on Antarctic Names The Advisory Committee on Antarctic Names (ACAN or US-ACAN) is an advisory committee of the United States Board on Geographic Names responsible for recommending commemorative names for features in Antarctica. History The committee was established ...

for Commander H.K. Butcher,

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...

, air operations officer on the Staff of the U.S. Naval Support Force, Antarctica, during U.S. Navy Operation Deepfreeze 1963 and 1964.

Geology

Butcher Ridge is a deeply eroded

silicic Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. Granite and rhyolite are the most common silicic rocks. Silicic is the group ...

igneous intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

. It consists of a

hypabyssal A subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at depths less than within the crust, and has intermediate grain size and often porphyritic texture between that of volcanic rocks and plutonic roc ...

intrusion that contains rhythmically layered glassy rocks and

plutonic Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...

rocks that vary in composition from

basaltic Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% ...

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained ( aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The min ...

." U-Pb dating of

baddeleyite Baddeleyite is a rare zirconium oxide mineral (ZrO2 or zirconia), occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high indices of refraction, and ranges from colorless to yellow, green, and dar ...

from the Butcher Ridge yielded an age of about 182.4

Myr The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

. This age confirms that this igneous complex was emplaced contemporaneously with the

Ferrar large igneous province Ferrar is a surname. Notable people with the surname include: *Ada Ferrar (1867–1951), British actress *Beatrice Ferrar (1876–1958), British actress *Bill Ferrar (1893–1990), English mathematician *Catherine Ferrar (born 1940), American tel ...

.Nelson, D.A., Cottle, J.M. and Schoene, B., 2019. ''Butcher Ridge igneous complex: A glassy layered silicic magma distribution center in the Ferrar large igneous province, Antarctic.'' ''Antarctica. Bulletin'', 132(5-6), pp.1201-1216. Faure and Mensing argue that the glassy and "pseudo-

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 ...

" rocks that compose the majority of the Butcher Ridge igneous complex are incompatible with it being a hypabyssal intrusion. Based on this and together with an associated strong

magnetic anomaly In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...

and other features, they concluded that the Butcher Ridge igneous complex should be seriously investigated as a possible

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...

impact structure An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface ...

Features

Gjelsvik Spur

. A rock spur northwest of

on the Butcher Ridge, in the Cook Mountains. It was named after Per Gjelsvik of the

University of Wisconsin–Madison A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase ''universitas magistrorum et scholarium'', which ...

aeromagnetic project under John Behrendt, 1963–64. Working from

aircraft, Gjelsvik acquired aeromagnetic profiles over the

Transantarctic Mountains The Transantarctic Mountains (abbreviated TAM) comprise a mountain range of uplifted (primarily sedimentary) rock in Antarctica which extend, with some interruptions, across the continent from Cape Adare in northern Victoria Land to Coats Land. ...

bordering the

Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who vi ...

and

Ross Ice Shelf The Ross Ice Shelf is the largest ice shelf of Antarctica (, an area of roughly and about across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than long, and between h ...

McCafferty Spur

. A spur on the north face of Butcher Ridge, in the Cook Mountains of Antarctica, northwest of

. It was named after

Anne McCafferty Anne, alternatively spelled Ann, is a form of the Latin female given name Anna. This in turn is a representation of the Hebrew Hannah, which means 'favour' or 'grace'. Related names include Annie. Anne is sometimes used as a male name in the N ...

, a geophysicist with the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

(USGS), who in 1991–92 worked on a USGS aeromagnetic survey over the

and, in a cooperative USGS–German project, participated in the first aeromagnetic flight across the Butcher Ridge and Cook Mountains.

References

Sources

* * Ridges of Oates Land {{OatesLand-geo-stub