Radiohalos or pleochroic halos are microscopic, spherical shells of discolouration within minerals such as biotite that occur in granite and other igneous rocks, wider interest has been prompted by the claims of a creationist, by Robert V. Gentry, an American young Earth creationist and nuclear physicist, known for his claims that radiohalos provide evidence for a young age of what?
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Radiohalo Radiohalos or pleochroic halos are microscopic, spherical shells of discolouration within minerals such as biotite that occur in granite and other igneous rocks. The shells are zones of radiation damage caused by the inclusion of minute radioactive crystals within the host crystal structure. The inclusions are typically zircon, apatite, or titanite which can accommodate uranium or thorium within their crystal structures . One explanation is that the discolouration is caused by alpha particles emitted by the nuclei; the radius of the concentric shells are proportional to the particle's energy . The phenomenon of radiohalos has been known to geologists since the early part of the 20th century, but wider interest has been prompted by the claims of creationist Robert V. Gentry that radiohalos in biotite are evidence for a young earth .
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Robert V. Gentry Robert V. Gentry (born 1933) is an American young Earth creationist and nuclear physicist, known for his claims that radiohalos provide evidence for a young age of the Earth. He is a member of the Seventh-day Adventist Church.
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Spheroidal weathering Spheroidal weathering is a form of chemical weathering that affects jointed bedrock and results in the formation of concentric or spherical layers of highly decayed rock within weathered bedrock that is known as "saprolite." When saprolite is exposed by physical erosion, these concentric layers peel (spall) off as concentric shells much like the layers of a peeled onion. Within saprolite, spheroidal weathering often creates rounded boulders, known as "corestones" or "woolsack", of relatively unweathered rock. Spheroidal weathering is also called onion skin weathering, concentric weathering, spherical weathering, or woolsack weathering.
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Znucalite Znucalite or CaZn(UO)(CO)(OH)·4(HO) is a rare, radioactive, white to pale cream colored uranium-containing carbonate mineral, hydrated calcium zinc uranyl carbonate hydroxide. Znucalite crystallizes in the orthorhombic system, often forming aggregates or crusts, and is found as a rare secondary species in carbonate-hosted (meaning it is mined from carbonate containing formations such as limestone) polymetallic veins, and nearby oxidizing uranium veins; on dump material and coating mine walls, apparently of post-mine origin. It fluoresces yellow-green under UV light.
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Theralite Theralite (from Greek "to pursue") is, in petrology, the name given to calcic foidal gabbro, a plutonic hylocrystalline rock consisting of augite, olivine, calcic plagioclase (labradorite), and nepheline, along with accessories including biotite, magnetite, ilmenite and analcime.
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Pedosphere The pedosphere (from Greek πέδον "pedon" "soil" or "earth" and σφαῖρα "sphaira" "sphere") is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The sum total of all the organisms, soils, water and air is termed as the "pedosphere". The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms), lithosphere (unconsolidated regolith and consolidated bedrock) and the hydrosphere (water in, on and below the soil). The pedosphere is the foundation of terrestrial life on this planet. There is a realization that the pedosphere needs to be distinctly recognized as a dynamic interface of all terrestrial ecosystems and be integrated into the Earth system science knowledge base.
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Scriptural geologist Scriptural geologists (or Mosaic geologists) were a heterogeneous group of writers in the early nineteenth century, who claimed "the primacy of literalistic biblical exegesis" and a short Young Earth time-scale. Their views were marginalised and ignored by the scientific community of their time. They "had much the same relationship to 'philosophical' (or scientific) geologists as their indirect descendants, the twentieth-century creationists." Paul Wood describes them as "mostly Anglican evangelicals" with "no institutional focus and little sense of commonality". They generally lacked any background in geology, and had little influence even in church circles.
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Don L. Anderson Don Lynn Anderson (March 5, 1933 – December 2, 2014) was an American geophysicist who made significant contributions to the understanding of the origin, evolution, structure, and composition of Earth and other planets. An expert in numerous scientific disciplines, Anderson’s work combined seismology, solid state physics, geochemistry and petrology to explain how the Earth works. Anderson was best known for his contributions to the understanding of the Earth’s deep interior, and more recently , for the hypothesis that hotspots are the product of plate tectonics rather than narrow plumes emanating from the deep Earth. Anderson was Professor (Emeritus) of Geophysics in the Division of Geological and Planetary Sciences at the California Institute of Technology (Caltech). He received numerous awards from geophysical, geological and astronomical societies. In 1998 he was awarded the prestigious Crafoord Prize by the Royal Swedish Academy of Sciences along with Adam Dziewonski. Later that year, Anderson received the National Medal of Science. He held honorary doctorates from Rensselaer Polytechnic Institute (where he did his undergraduate work in geology and geophysics) and the University of Paris (Sorbonne), and served on numerous university advisory committees, including those at Harvard, Princeton, Yale, University of Chicago, Stanford, University of Paris, Purdue University, and Rice University. Anderson’s wide-ranging research resulted in hundreds of published papers in the fields of planetary science, seismology, mineral physics, petrology, geochemistry, tectonics and the philosophy of science. He continued to work and publish until his death. His widely known textbooks, Theory of the Earth, and New Theory of the Earth are regarded by colleagues as compelling syntheses of the origins of the Earth and its inner workings by one of the great geophysical authorities of our time.
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Geology Geology (from the Ancient Greek γῆ, "gē", i.e. "earth" and -λoγία, "-logia", i.e. "study of, discourse") is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer to the study of the solid features of any terrestrial planet or natural satellite, (such as Mars or the Moon).
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Granulite Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism. They are medium to coarse–grained and mainly composed of feldspars sometimes associated with quartz and anhydrous ferromagnesian minerals, with granoblastic texture and gneissose to massive structure. They are of particular interest to geologists because many granulites represent samples of the deep continental crust. Some granulites experienced decompression from deep in the Earth to shallower crustal levels at high temperature; others cooled while remaining at depth in the Earth.
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Large igneous province In geology, a large igneous province (LIP) is an extremely large accumulation of igneous rocks, including plutonic rocks (intrusive) or volcanic rock formations (extrusive), arising when hot magma extrudes from inside the Earth and flows out. The source of many or all LIPs is variously attributed to mantle plumes or to processes associated with plate tectonics. Types of LIPs can include "large volcanic provinces" (LVP), created through flood basalt, and "large plutonic provinces" (LPP). Rampino and Stothers (1988) cite eleven distinct flood-basalt episodes - occurring in the past 250 million years - which created volcanic provinces and plateaus and coincided with mass extinctions. However, more flood basalts have been recognized, such as the large Ontong Java Plateau, and the medium-sized Chilcotin Group, though the latter may be linked to the Columbia River Basalt Group. Formation depends on a range of factors, such as continental configuration, latitude, volume, rate, duration of eruption, style and setting (continental vs. oceanic), the pre-existing climate state, and the biota resilience to change.
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Scoria Scoria is a highly vesicular, dark colored volcanic rock that may or may not contain crystals (phenocrysts). It is typically dark in color (generally dark brown, black or purplish red), and basaltic or andesitic in composition. Scoria is relatively low in density as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water. The holes or vesicles form when gases that were dissolved in the magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta (lapilli, blocks and bombs), for instance in Strombolian eruptions that form steep-sided scoria cones. Most scoria is composed of glassy fragments, and may contain phenocrysts. The word "scoria" comes from the Greek σκωρία, "skōria", rust. An old name for scoria is cinder.
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Biosignature A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical and chemical structures and also its utilization of free energy and the production of biomass and wastes. Due to its unique characteristics, a biosignature can be interpreted as having been produced by living organisms; however, it is important that they not be considered definitive because there is no way of knowing in advance which ones are universal to life and which ones are unique to the peculiar circumstances of life on Earth. Nonetheless, life forms are known to shed unique chemicals, including DNA, into the environment as evidence of their presence in a particular location.
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Lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of the gross physical character of a rock. It is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7.
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Tephrochronology Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed. Such an established event provides a "tephra horizon". The premise of the technique is that each volcanic event produces ash with a unique chemical "fingerprint" that allows the deposit to be identified across the area affected by fallout. Thus, once the volcanic event has been independently dated, the tephra horizon will act as time marker.
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Manganese nodule Polymetallic nodules, also called manganese nodules, are rock concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. The core may be microscopically small and is sometimes completely transformed into manganese minerals by crystallization. When visible to the naked eye, it can be a small test (shell) of a microfossil (radiolarian or foraminifer), a phosphatized shark tooth, basalt debris or even fragments of earlier nodules. As nodules can be found in vast quantities, and contain valuable metals, deposits were identified as having economic interest in the 1960s by John Mero.
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Geobiology Geobiology is a field of scientific research that explores the interactions between the physical Earth and the biosphere. It is a relatively young field, and its borders are fluid. There is considerable overlap with the fields of ecology, evolutionary biology, microbiology, paleontology, and particularly biogeochemistry. Geobiology applies the principles and methods of biology and geology to the study of the ancient history of the co-evolution of life and Earth as well as the role of life in the modern world. Geobiologic studies tend to be focused on microorganisms, and on the role that life plays in altering the chemical and physical environment of the lithosphere, atmosphere, hydrosphere and/or cryosphere. It differs from biogeochemistry in that the focus is on processes and organisms over space and time rather than on global chemical cycles.
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Pelite A pelite (Ancient Greek "pelos", clay) is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a "metapelite". It was equivalent to the now little-used Latin-derived term lutite. A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature.
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Extinct radionuclide An extinct radionuclide is a radionuclide that was formed by nucleosynthesis before the formation of the Solar System, about 4.6 billion years ago, and incorporated into it, but has since decayed to virtually zero abundance, due to having a half-life shorter than about 100 million years.
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List of ophiolites Ophiolites are sequences of mafic to ultramafic rock generally believed to represent ancient oceanic lithosphere. They are distributed all across the world being all of them located at present or past orogenic belts, sites of "mountain building" processes.
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Paleontology in Hawaii Paleontology in Hawaii refers to paleontological research occurring within or conducted by people from the U.S. state of Hawaii. The Hawaiian islands began to form as a result of volcanic activity about 5 million years ago. Due to their young age and igneous geology they preserve very few fossils. Most such remains are creatures like relatively recent corals and molluscs that lived in the area when sea levels were higher than they are today. Overall the state has seen very little paleontological research within its borders. According to author Marian Murray prior to the 1974 publication of the second edition to her book Hunting for Fossils most of the little research on Hawaii's fossils record had already gone out of print. She recommended that would-be amateur fossil hunters in Hawaii consult staff of a local museum for clues on where to hunt due to the rarity of fossils and the lack of easily accessible information on them.
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Marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble may be foliated. Geologists use the term "marble" to refer to metamorphosed limestone; however, stonemasons use the term more broadly to encompass unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material.