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Kneeling Nun Tuff
The Kneeling Nun Tuff is a geologic formation exposed in southwest New Mexico. It has a radiometric age of 35.3 million years, corresponding to the latest Eocene epoch. The formation consists of over of tuff erupted by the Emory caldera of the Mogollon-Datil volcanic field. It has been studied by geologists seeking to understand the processes whereby supereruptions are triggered. Description The formation consists of reddish brown to pinkish gray tuff containing numerous visible crystals ( phenocrysts), up to in size, composed of quartz, lesser amounts of sanidine and plagioclase feldspar, and minor biotite. At the type location, the tuff has pronounced columnar jointing and faint horizontal sheeting. The overall composition of the tuff is largely rhyolitic, but with some quartz latite beds. The formation was erupted from the Emory caldera () of the Mogollon-Datil volcanic field. It includes an intracaldera facies that is over in thickness and an outflow fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
City Of Rocks State Park
City of Rocks State Park is a state park in New Mexico, consisting of large sculptured rock formations in the shape of pinnacles or boulders rising as high as . Geology The bedrock forming City of Rocks was created 34.9 million years ago by a volcanic eruption. Then over millions of years, erosion sculpted the rock formations seen today. The eruption was from the Emory Caldera, centered near Hillsboro Peak at the southern end of the Black Range. The eruption was estimated to be a VEI 8 eruption, and it emplaced the Kneeling Nun Tuff, a tuff bed covering an area of , which makes up the bedrock of the park. History The Mimbreno Indians settled in the area from 750 to 1250 AD. Pottery, arrowheads, and other artifacts show evidence of prehistoric Indians in the area. Indian wells, or conical holes, are found in the rocks where water would be allowed to collect. Chapter 110 of the 1953 Laws of New Mexico created City of Rocks State Park on March 20, 1953. This legislation provide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sanidine
Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8). Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures. At yet lower temperatures, microcline, a triclinic polymorph of potassium feldspar, is stable. Due to the high temperature and rapid quenching, sanidine can contain more sodium in its structure than the two polymorphs that equilibrated at lower temperatures. Sanidine and high albite constitute a solid solution series with intermediate compositions termed anorthoclase. Exsolution of an albite phase does occur; resulting cryptoperthite can best be observed in electron microprobe images. Occurrence In addition to its presence in the groundmass of felsic rocks, sanidine is a common phenocryst in rhyolites and, to a lesser extent, rhyodacites. Trachyte consists largely of fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The lithosphere is broken into tectonic plates whose motion allows heat to escape from the interior of the Earth into space. The crust lies on top of the mantle, a configuration that is stable because the upper mantle is made of peridotite and is therefore significantly denser than the crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. The temperature of the crust increases with depth, reaching values typically in the range from about to at the boundary with the underlying mantle. The temperature increases by as much as for every kilometer locally in the upper part of the crust Composition File:Elemental abundances.svg, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma Chamber
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upwards. If the magma finds a path to the surface, then the result will be a volcanic eruption; consequently, many volcanoes are situated over magma chambers. These chambers are hard to detect deep within the Earth, and therefore most of those known are close to the surface, commonly between 1 km and 10 km down. Dynamics of magma chambers Magma rises through cracks from beneath and across the crust because it is less dense than the surrounding rock. When the magma cannot find a path upwards it pools into a magma chamber. These chambers are commonly built up over time, by successive horizontal or vertical magma injections. Influx of new magma causes reaction of pre-existing crystals and the pressure in the chamber to increase. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Top Formation
The Bell Top Formation is a geologic formation in southern New Mexico. Radiometric dating of surrounding tuffs indicate that it was deposited in the Oligocene epoch. Description The formation consists of tuffaceous sandstone and minor conglomerate. These are interbedded with volcanic tuffs and flows that are assigned to the Mogollon Group. Total thickness may be as much as . In the southeastern part of the Mogollon-Datil volcanic field, the upper beds of the Bell Top Formation define the break between the Mogollon Group and the Datil Group. Here the Bell Top rests on the 33.51 Ma Box Canyon Tuff, the uppermost unit of the Datil Group, and below the 28.56 Ma Vicks Peak Tuff, the lowest tuff of the Mogollon Group. In other locations, it overlies the Palm Park Formation. The formation has been interpreted as sediments eroded from caldera rims of the Mogollon-Datil volcanic field. Oxygen isotope ratios suggest that the magma from which the caldera rims solidified had its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Mexico Tech
The New Mexico Institute of Mining and Technology (New Mexico Tech and formerly New Mexico School of Mines) is a public university in Socorro, New Mexico. It offers over 30 bachelor of science degrees in technology, the sciences, engineering, management, and technical communication, as well as graduate degrees at the masters and doctoral levels.Carey, John A. (February 2003) "New Mexico Tech One of State's Best Assets" ''New Mexico Business Journal'' 27:2 pp48-49 History With 1,244 undergraduate students as of 2021, New Mexico Tech is a relatively small university focused on science and engineering. The institution was founded by the New Mexico Territorial Legislature in the year 1889 as the New Mexico School of Mines to both boost the territorial economy and teach mining specialties on the college level. During the 1930s, petroleum engineering and technology also became an important field of study at the institute. In 1946, New Mexico Tech began offering graduate degrees. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outflow Sheet
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish ', and Latin ', meaning "c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facies (geology)
In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formation), and the changes that may occur in those attributes over a geographic area. A facies encompasses all of the characteristics of a rock including its chemical, physical, and biological features that distinguish it from adjacent rock. The term facies was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy, which replaced the earlier notions of Neptunism. Types of facies Sedimentary facies Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative. Sedimentary facies are bodies of sediment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a Volcanic crater, crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish language, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz Latite
A quartz latite is a volcanic rock or fine grained extrusive rock composed mostly of alkali feldspar and plagioclase with some quartz. It forms from the rapid cooling of magma of intermediate composition but moderately enriched in alkali metal oxides. Quartz latite is intermediate between latite and rhyolite in its mineralogy. Description Quartz latite is the fine-grained equivalent of a quartz monzonite, containing approximately equal amounts of plagioclase and alkali feldspar and between 5% and 20% quartz and with plagioclase making up 35% to 65% of its total feldspar content. Quartz latite is not a recognized rock type in the TAS classification used to chemically classify glassy or very fine-grained volcanic rock. Occurrence Quartz latite is found in the 130-135 Mya Etendeka Formation of Namibia, where it forms extensive sheets in association with tholeiitic basalt. These are interpreted as densely welded ash flow tuffs. Some of the quartz latite flows were enormous, with e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolitic
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 mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description Rhyolite is an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columnar Jointing
Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as Joint (geology), joints, result in the formation of a regular array of polygonal Prism (geometry), prisms, or columns. Columnar jointing occurs in many types of igneous rocks and forms as the rock cools and contracts. Columnar jointing can occur in cooling lava flows and ashflow tuffs (ignimbrites), as well as in some shallow intrusions. Columnar jointing also occurs rarely in sedimentary rocks if they have been heated by nearby hot magma. The columns can vary from 3 meters to a few centimeters in diameter, and can be as much as 30 meters tall. They are typically parallel and straight, but can also be curved and vary in diameter. An array of regular, straight, and larger-diameter columns is called a colonnade; an irregular, less-straight, and smaller-diameter array is termed an entablature. The number of sides of the individual columns can vary from 3 to 8, with 6 sides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
