query: where do rocks become sediment inside the earth or on the surface of the earth

pos: Sedimentary rock Sedimentary rock Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). Before being deposited, the geological detritus was formed by weathering and erosion from the source area, and then transported to the place of deposition by water,

pos: Earth eruptions, flooding, weathering, glaciation, the growth of coral reefs, and meteorite impacts are among the processes that constantly reshape the Earth's surface over geological time. The continental crust consists of lower density material such as the igneous rocks granite and andesite. Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes buried and compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the crust. The third form of rock material found on

pos: Geology of solar terrestrial planets is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form only about 5% of the crust. The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene, and olivine. Common carbonate minerals include calcite

pos: Archean felsic volcanic rocks rocks. Altered feldspars in the rocks may result in such anomalous signatures. Archean felsic volcanic rocks Archean felsic volcanic rocks are felsic volcanic rocks that were formed in the Archean Eon (4 to 2.5 billion years ago). The term "felsic" means that the rocks have silica content of 62–78%. Given that the Earth formed at ~4.5 billion year ago, Archean felsic volcanic rocks provide clues on the Earth's first volcanic activities on the Earth's surface started 500 million years after the Earth's formation. As the Archean Earth was two or three time hotter than the present, formation of felsic volcanic

pos: Archean felsic volcanic rocks Archean felsic volcanic rocks Archean felsic volcanic rocks are felsic volcanic rocks that were formed in the Archean Eon (4 to 2.5 billion years ago). The term "felsic" means that the rocks have silica content of 62–78%. Given that the Earth formed at ~4.5 billion year ago, Archean felsic volcanic rocks provide clues on the Earth's first volcanic activities on the Earth's surface started 500 million years after the Earth's formation. As the Archean Earth was two or three time hotter than the present, formation of felsic volcanic rocks may differ from the modern plate tectonics. Archean felsic volcanic rocks

pos: Earth analog probable frequency and distribution of Earth-like planets. Another criterion often cited is that an Earth analog must be terrestrial, that is, it should possess a similar surface geology—a planetary surface composed of similar surface materials. The closest known examples are Mars and Titan and while there are similarities in their types of landforms and surface compositions, there are also significant differences such as the temperature and quantities of ice. Many of Earth's surface materials and landforms are formed as a result of interaction with water (such as clay and sedimentary rocks) or as a byproduct of life (such as limestone

pos: Origin of water on Earth Origin of water on Earth The origin of water on Earth, or the reason that there is clearly more liquid water on Earth than on the other rocky planets of the Solar System, is not completely understood. There exist numerous more or less mutually compatible hypotheses as to how water may have accumulated on Earth's surface over the past 4.5 billion years in sufficient quantity to form oceans. Gradual "dehydration melting"—leakage of water stored in hydrate minerals of Earth's rocks—could have formed a portion of its water. Water may also have come from volcanism: water vapor in the atmosphere that

pos: Snowball Earth which would dissolve into the oceans to form carbonic acid. Although the boron variations may be evidence of extreme climate change, they need not imply a global glaciation. Earth's surface is very depleted in the element iridium, which primarily resides in the Earth's core. The only significant source of the element at the surface is cosmic particles that reach Earth. During a snowball Earth, iridium would accumulate on the ice sheets, and when the ice melted the resulting layer of sediment would be rich in iridium. An iridium anomaly has been discovered at the base of the cap carbonate formations,

pos: Detention dam dams built to restrict flow rate regulate the amount water released into channels. Detentions dams used to replenishment the subsurface water or groundwater hold surface runoff to allow the ground to absorb the water. Groundwater is water that has drained into an aquifer due to the force of gravity. An aquifer is layers of permeable soils and rocks below the earth's surface that allow water to accumulated between the rocks and soils. Debris dams are a type of detention dam used to collect sediment to prevent it from flowing into areas where large sediment buildup may be damaging. Detention dams

pos: Oldest dated rocks Oldest dated rocks The oldest dated rocks on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history. Such rocks are exposed on the Earth's surface in very few places. Some of the oldest surface rock can be found in the Canadian Shield, Australia, Africa and in a few other old regions around the world. The ages of these felsic rocks are generally between 2.5 and 3.8 billion years. The approximate ages have a margin of error

pos: Geothermal gradient until it reaches an inflection point where it joins the stabilized heat-flow regime. In deep boreholes, the temperature of the rock below the inflection point generally increases with depth at rates of the order of 20 K/km or more. Fourier's law of heat flow applied to the Earth gives "q" = "Mg" where "q" is the heat flux at a point on the Earth's surface, "M" the thermal conductivity of the rocks there, and "g" the measured geothermal gradient. A representative value for the thermal conductivity of granitic rocks is "M" = 3.0 W/mK. Hence, using the global average geothermal

pos: Sedimentary rock between successive layers indicate changes to the environment over time. Sedimentary rocks can contain fossils because, unlike most igneous and metamorphic rocks, they form at temperatures and pressures that do not destroy fossil remains. Sedimentary rock Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of

pos: Equivalence principle of gravitational acceleration at the Earth's surface) is equivalent to the acceleration of an inertially moving body that would be observed on a rocket in free space being accelerated at a rate of 1"g". Einstein stated it thus: That is, being on the surface of the Earth is equivalent to being inside a spaceship (far from any sources of gravity) that is being accelerated by its engines. The direction or vector of acceleration equivalence on the surface of the earth is "up" or directly opposite the center of the planet while the vector of acceleration in a spaceship is directly

pos: Ultra-high-pressure metamorphism deep in Earth. UHP xenoliths of crustal affinity provide information about processes active deep in Earth, but also information about what kinds of crustal rocks reach great depth in Earth and how profound those depths are. Regional metamorphic UHP terrains exposed on Earth's surface provide considerable information that is not available from xenoliths. Integrated study by structural geologists, petrologists, and geochronologists has provided considerable data on how the rocks deformed, the pressures and temperatures of metamorphism, and how the deformation and metamorphism varied as a function of space and time. It has been postulated that small UHP terrains that underwent

pos: Aeolian landform Aeolian landform Aeolian landforms are features of the Earth's surface produced by either the erosive or constructive action of the wind. This process is not unique to the Earth, and it has been observed and studied on other planets, including Mars. The word derives from Æolus, the Greek god of the winds, and the son of Hellen and the nymph Orseis, and a brother of Dorus, Xuthus and Amphictyon. In aeolian processes, wind transports and deposits particles of sediment. Aeolian features form in areas where wind is the primary source of erosion. The particles deposited are of sand, silt and

neg: Water that occurs on the surface of the earth. Deposition of transported sediment forms many types of sedimentary rocks, which make up the geologic record of Earth history. The water cycle (known scientifically as the hydrologic cycle) refers to the continuous exchange of water within the hydrosphere, between the atmosphere, soil water, surface water, groundwater, and plants. Water moves perpetually through each of these regions in the "water cycle" consisting of following transfer processes: Most water vapor over the oceans returns to the oceans, but winds carry water vapor over land at the same rate as runoff into the sea, about

neg: Oldest dated rocks streak of minerals in a mylonite, representing a layer of sediment or an old dike. This may be difficult to find or map; hence, the oldest dates yet resolved are as much generated by luck in sampling as by understanding the rocks themselves. It is thus premature to claim that any of these rocks, or indeed that of other formations of Hadean gneisses, is the oldest formations or rocks on Earth; doubtless, new analyses will continue to change our conceptions of the structure and nature of these ancient continental fragments. Nevertheless, the oldest cratons on Earth include the Kaapvaal Craton,

neg: Provenance (geology) Provenance (geology) Provenance in geology, is the reconstruction of the origin of sediments. The Earth is a dynamic planet, and all rocks are subject to transition between the three main rock types: sedimentary, metamorphic, and igneous rocks (the rock cycle). Rocks exposed to the surface are sooner or later broken down into sediments. Sediments are expected to be able to provide evidence of the erosion history of their parent source rocks. The purpose of provenance study is to restore the tectonic, paleo-geographic and paleo-climatic history. In the modern geological lexicon, "sediment provenance" specifically refers to the application of compositional analyses

neg: Photogeochemistry Earth, since that is where sunlight is available (although other sources of light such as chemiluminescence would not be strictly excluded from photogeochemical study). Reactions may occur among components of land such as rocks, soil and detritus; components of surface water such as sediment and dissolved organic matter; and components of the atmospheric boundary layer directly influenced by contact with land or water, such as mineral aerosols and gases. Visible and medium- to long-wave ultraviolet radiation is the main source of energy for photogeochemical reactions; wavelengths of light shorter than about 290 nm are completely absorbed by the present atmosphere,

neg: Mudrock sedimentary rocks in the geologic record, and are easily the most widespread deposits on Earth. Fine sediment is the most abundant product of erosion, and these sediments contribute to the overall omnipresence of mudrocks. With increased pressure over time the platey clay minerals may become aligned, with the appearance of parallel layering (fissility). This finely bedded material that splits readily into thin layers is called "shale", as distinct from "mudstone". The lack of fissility or layering in mudstone may be due either to the original texture or to the disruption of layering by burrowing organisms in the sediment prior to

neg: Partial melting to the chemical differentiation of crustal rocks. Virtually all rocks on Earth derive from material from the interior of the earth that has been partially melted. The main places where partial melting occurs are subduction zones, mid-ocean ridges and hotspots. In all these places partial melting is often associated with volcanism, although some melts do not make it to the surface. Partial melts are thought to play an important role in enriching old parts of the continental lithosphere in incompatible elements. Partial melts produced at depth move upwards due to the compaction of the surrounding matrix. Partial melting Partial melting

neg: Water water on Earth is sea water. Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers. Water is important in many geological processes. Groundwater is present in most rocks, and the pressure of this groundwater affects patterns of faulting. Water in the mantle is responsible for the melt that produces volcanoes at subduction zones. On the surface of the Earth, water is important in both chemical and physical weathering processes. Water, and to a lesser but still significant extent, ice, are also responsible for a large amount of sediment transport

neg: Geochemical cycle erupts onto the surface of the Earth. This molten rock magma then cools and crystallizes, forming igneous rocks. If crystallization occurs at the Earth´s surface, extrusive igneous rocks are formed; if crystallization occurs within the Earth´s lithosphere, intrusive igneous rocks are formed which can then be brought to Earth´s surface by denudation. Categories and examples of geochemical cycles: Geochemical cycle In Earth science, a geochemical cycle is the pathway that chemical elements take in the surface and crust of the Earth. The term "geochemical" tells us that geological and chemical factors are all included. The migration of heated and compressed

neg: Age of the Earth it would take for the near-surface to cool to its present temperature. His calculations did not account for heat produced via radioactive decay (a process then unknown to science) or, more significantly, convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface. Even more constraining were Kelvin's estimates of the age of the Sun, which were based on estimates of its thermal output and a theory that the Sun obtains its energy from gravitational collapse; Kelvin estimated that the Sun is about 20 million years old. Geologists such as Charles Lyell

neg: Vesicular texture Vesicular texture Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside. This texture is common in aphanitic, or glassy, igneous rocks that have come to the surface of the earth, a process known as extrusion. As magma rises to the surface the pressure on it decreases. When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas

neg: Mudrock environment on Earth, the majority are found in lakes and oceans. Heavy rainfall provides the kinetic motion necessary for mud, clay, and silt transport. Southeast Asia, including Bangladesh and India, receives high amounts of rain from monsoons, which then washes sediment from the Himalayas and surrounding areas to the Indian Ocean. Warm, wet climates are best for weathering rocks, and there is more mud on ocean shelves off tropical coasts than on temperate or polar shelves. The Amazon system, for example, has the third largest sediment load on Earth, with rainfall providing clay, silt, and mud from the Andes in

neg: Thomas Gold there was no reason to believe "that on Earth they must be biological in origin". Gold proposed that fuels were trapped inside the core of the Earth in randomized molecular form nearly 4.5 billion years ago. Over time, the extreme heat of the core "sweated" the rocks that contained these molecules, pushing them up through the porous layers of the Earth. As they move up toward the surface, the hydrocarbons fueled the development of large microbial colonies, which served as the basis for life on Earth. The migrating fossil fuels collect biological remnants before becoming trapped in deep underground reservoirs.

neg: Lutite derived it from the Latin word for mud. He also proposed a number of prefixes to be used with and attached to "lutite" in order to designated various types of lutites. None of these prefixes are used by Earth scientists nowadays. Pettijohn gives the following descriptive terms based on grain size, avoiding the use of terms such as "clay" or "argillaceous" which carry an implication of chemical composition: Lutite Lutite is old terminology, which is not widely used, by Earth scientists in field descriptions for fine-grained, sedimentary rocks, which are composed of silt-size sediment, clay-size sediment, or a mixture of

neg: Vertical and horizontal robust sophisticated instruments and work on the same fundamental principle. In the flat earth scenario, where the earth is notionally a large (infinite) flat surface with gravitational field at a right angle to the surface, the earth surface is horizontal and any plane parallel to the earth surface is also horizontal. Vertical planes, e.g., walls, may be parallel to each other or they may intersect at a vertical line. Horizontal surfaces do not intersect. Furthermore, a plane cannot both be a horizontal plane at one place and a vertical plane somewhere else. When the curvature of the earth is taken

neg: Hollow Earth the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm, and typical densities of surface rocks are only half that (about 2.75 g/cm). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging

neg: Geodiversity Geodiversity Geodiversity is the variety of earth materials, forms and processes that constitute and shape the Earth, either the whole or a specific part of it. Relevant materials include minerals, rocks, sediments, fossils, soils and water. Forms may comprise folds, faults, landforms and other expressions of morphology or relations between units of earth material. Any natural process that continues to act upon, maintain or modify either material or form (for example tectonics, sediment transport, pedogenesis) represents another aspect of geodiversity. However geodiversity is not normally defined to include the likes of landscaping, concrete or other significant human influence. Geodiversity is

neg: Sediment sediment deposition undergoes a hydrodynamic sorting process within the marine environment leading to a seaward fining of sediment grain size. One cause of high sediment loads is slash and burn and shifting cultivation of tropical forests. When the ground surface is stripped of vegetation and then seared of all living organisms, the upper soils are vulnerable to both wind and water erosion. In a number of regions of the earth, entire sectors of a country have become erodible. For example, on the Madagascar high central plateau, which constitutes approximately ten percent of that country's land area, most of the land

neg: Open-pit mining Open-pit mining Open-pit, open-cast or open cut mining is a surface mining technique of extracting rock or minerals from the earth by their removal from an open pit or borrow. This form of mining differs from extractive methods that require tunneling into the earth, such as long wall mining. Open-pit mines are used when deposits of commercially useful ore or rocks are found near the surface; that is, where the overburden (surface material covering the valuable deposit) is relatively thin or the material of interest is structurally unsuitable for tunnelling (as would be the case for sand, cinder, and gravel).

neg: Flute (glacial) Flute (glacial) A glacial flute is a landform created by the movement of a glacier around a boulder. They are long ridges on the ground parallel to the movement. Examples can be found in many places including Iceland, Alaska and Canada. As glaciers move along the surface of the earth, rocks are slowly mixed in with the ice. Rocks may reach the bottom of the glacier and begin to scrape along the earth. Eventually boulder sized rocks become lodged in the ground. Once the boulder is in place, the glacier flows around it. As a result, a cavity is formed

neg: Incremental dating layer or layers of sediment. Typically, varve refers to lake or glacial sediment), as temperature induced changes in the isotopic ratios for oxygen isotopes in sediments, and in the relative abundance of fossils. Because these can be calibrated reliably over a period of 40 million years this provides an alternate verification to radiometric dating in cases where sufficient record exists to provide a reliable trace. Polarity reversals in the Earth's magnetic field have also been used to determine geologic time. Periodically, the magnetic field of the earth reverses leaving a magnetic signal in volcanic and sedimentary rocks. This signal can

neg: Cueva Fell hard clay. Remnants of sandstone still clinging to the conglomerate roof eventually fell to the floor, forming an archaeologically sterile layer that separated later human occupation periods. Junius Bird labelled the occupational sediment layers of the site from top to bottom, the top layer directly under the surface is I and the oldest, lowest layer is V. The surface material of the site is composed of dirt, rocks, and hard-packed sheep manure. The surface layer ranges from in thickness. The youngest stratigraphic layer of Fell’s Cave is a dark earth layer, reaching approximately in thickness. This component dates from around

neg: Moon rock the three astronauts on the Apollo 11 mission: Armstrong, Aldrin and Collins. Because of their rarity on Earth, and the difficulty of obtaining more, Moon rocks have been frequent targets of theft and vandalism, and many have gone missing or were stolen. Moon rock Moon rock or lunar rock is rock that is found on the Earth's moon including lunar material collected during the course of human exploration of the Moon, or rock that has been ejected naturally from the Moon's surface (and which has then landed on the Earth as meteorites). Moon rocks on Earth come from three sources:

neg: Moon rock Moon rock Moon rock or lunar rock is rock that is found on the Earth's moon including lunar material collected during the course of human exploration of the Moon, or rock that has been ejected naturally from the Moon's surface (and which has then landed on the Earth as meteorites). Moon rocks on Earth come from three sources: those collected by the United States Apollo program manned lunar landings from 1969 to 1972; samples returned by three Soviet Luna programme unmanned probes in the 1970s; and rocks that were ejected naturally from the lunar surface. The Apollo missions collected 2,200

neg: Enchanted Moura It was also believed that pedras mouras had enchanted treasures inside them. There are several legends where the moura instead of being a stone lives inside the stone. In Portuguese lore it is said that you can walk into or walk out of certain rocks, possibly related to the moura legends. The moura is, also, described as traveling to the “mourama” (an enchanted place) while sitting on a stone that can float in the air or water. Inside caves, under rocks and under the earth many legends say there exist palaces with treasures. According to Thurnwald (cited in McKenna, 1938),

neg: Rare-earth element similar effect. In sedimentary rocks, rare-earth elements in clastic sediments are a representation provenance. The rare-earth element concentrations are not typically affected by sea and river waters, as rare-earth elements are insoluble and thus have very low concentrations in these fluids. As a result, when a sediment is transported, rare-earth element concentrations are unaffected by the fluid and instead the rock retains the rare-earth element concentration from its source. Sea and river waters typically have low rare-earth element concentrations. However, aqueous geochemistry is still very important. In oceans, rare-earth elements reflect input from rivers, hydrothermal vents, and aeolian sources; this

neg: Space architecture some geologic evidence suggests that Mars could have been warm and wet on a global scale in its distant past. Intense geologic activity has reshaped the surface of the Earth, erasing evidence of our earliest history. Martian rocks can be even older than Earth rocks, though, so exploring Mars may help us decipher the story of our own geologic evolution including the origin of life on Earth. Mars has an atmosphere, though its surface pressure is less than 1% of Earth's. Its surface gravity is about 38% of Earth's. Although a human expedition to Mars has not yet taken place,

neg: Regolith-hosted rare earth element deposits Regolith-hosted rare earth element deposits Regolith-hosted rare earth element deposits (also known as ion-adsoprtion deposits) are rare-earth element (REE) ores in decomposed rocks that are formed by intense weathering of REE-rich parental rocks (e.g. granite, tuff etc.) in subtropical areas. In these areas, rocks are intensely broken and decomposed. Then, REEs infiltrate downward with rain water and they are concentrated along a deeper weathered layer beneath the ground surface. Extraction technology of the deposits has been evolving over the last 50 years. In the past, REEs were primarily extracted in small amount as by-products in mines of other metals or

neg: Sediment transport (depending on flow conditions) sand often can be carried as both bed load and suspended load in the same stream or shoreface. Sediment transport Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural systems where the particles are clastic rocks (sand, gravel, boulders, etc.), mud, or clay; the fluid is air, water, or ice; and the force of gravity acts to move the particles along the sloping surface on which they are

neg: Sediment transport Sediment transport Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural systems where the particles are clastic rocks (sand, gravel, boulders, etc.), mud, or clay; the fluid is air, water, or ice; and the force of gravity acts to move the particles along the sloping surface on which they are resting. Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, and other bodies of water due to currents and

neg: Volcanism Volcanism Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. Magma from the mantle or lower crust rises through its crust towards the surface. If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous (thick)

neg: Kalambo Falls Kalambo Falls site as well as what their environment was like during times of occupation. Using plant (floral) and pollen analyses, Clark was able to conduct the process of paleoenvironmental reconstruction. By studying pollen that settled on the earth during different environmental settings, Clark was able to form a general idea of what ecological factors affected the Kalambo Falls region at different times. In order to do this, Clark used a tool for drawing out sediment cores in order to observe and analyse the different layers below the surface of the earth today. He separated these layers into 6 different

neg: Native cuisine of Hawaii earth ovens, or spitted over a fire during ceremonial feasts. Hawaiian earth ovens, known as an "imu", combine roasting and steaming in a method called "kālua". A pit is dug into earth and lined with volcanic rocks and other rocks that do not split when heated to a high temperature, such as granite. A fire is built with embers, and when the rocks are glowing hot, the embers are removed and the foods wrapped in "ti", ginger or banana leaves are put into the pit, covered with wet leaves, mats and a layer of earth. Water may be added through

neg: Cave diving beyond the reach of sunlight. The level of darkness experienced creates an environment impossible to see in without an artificial form of light. Caves often contain sand, mud, clay, silt, or other sediment that can further reduce underwater visibility in seconds when stirred up. Caves can carry strong water currents. Most caves emerge on the surface as either springs or siphons. Springs have out flowing currents, where water is coming up out of the Earth and flowing out across the land's surface. Siphons have in-flowing currents where, for example, an above-ground river is going underground. Some caves are complex and

neg: Sediment basin along a waterway or low-lying area on the site. They are typically installed at the perimeter of a site and above storm drain inlets, to keep sediment from entering the drainage system. Sediment traps are commonly used on small construction sites, where a sediment basin is not practical. Sediment basins are typically used on construction sites of or more, where there is sufficient room. Sediment traps are installed before land disturbance (earth moving, grading) begins on a construction site. The traps are often used in conjunction with erosion controls and other sediment control practices. Sediment basin A sediment basin is

neg: Planetary differentiation dome-shaped forms called diapirs when doing so. On Earth, salt domes are salt diapirs in the crust which rise through surrounding rock. Diapirs of molten low-density silicate rocks such as granite are abundant in the Earth's upper crust. The hydrated, low-density serpentinite formed by alteration of mantle material at subduction zones can also rise to the surface as diapirs. Other materials do likewise: a low-temperature, near-surface example is provided by mud volcanos. On the Moon, a distinctive basaltic material has been found that is high in "incompatible elements" such as potassium, rare earth elements, and phosphorus and is often referred

neg: Lutite Lutite Lutite is old terminology, which is not widely used, by Earth scientists in field descriptions for fine-grained, sedimentary rocks, which are composed of silt-size sediment, clay-size sediment, or a mixture of both. When mixed with water lutites often disintegrate into mud. Because this is a field term, there is a lack of any precise definition for it based upon specific grain-size characteristics. Lutites include a variety of fine-grained sedimentary rocks, including calcisiltite, calcilutite, claystone, mudstone, shale, and siltstone. It is equivalent to the term mudstone and the Greek-derived term pelite. Lutite was first used in 1904 by Grabau, who

neg: Regolith-hosted rare earth element deposits to its high chemical stability under high temperature. More importantly, it is responsible for the chemical reactions in the converter. For more applications of other rare earth elements, check "Rare-earth element#List". Regolith-hosted rare earth element deposits Regolith-hosted rare earth element deposits (also known as ion-adsoprtion deposits) are rare-earth element (REE) ores in decomposed rocks that are formed by intense weathering of REE-rich parental rocks (e.g. granite, tuff etc.) in subtropical areas. In these areas, rocks are intensely broken and decomposed. Then, REEs infiltrate downward with rain water and they are concentrated along a deeper weathered layer beneath the ground surface.

neg: Meander to the upper surface of point bar when the sediment is deposited the vertical sequence of sediments comprising a point bar becomes finer upward within an individual point bar. For example, it is typical for point bars to fine upward from gravel at the base to fine sands at the top. The source of the sediment is typically upstream cut banks from which sand, rocks and debris has been eroded, swept, and rolled across the bed of the river and downstream to the inside bank of a river bend. On the inside bend, this sediment and debris is eventually deposited

neg: Cuisine of Hawaii and dogs were killed by strangulation or by holding their nostrils shut, in order to conserve the animal's blood. Meat was prepared by flattening out the whole eviscerated animal and broiling it over hot coals, or it was spitted on sticks. Large pieces of meat, such as fowl, pigs and dogs, would be typically cooked in earth ovens, or spitted over a fire during ceremonial feasts. Hawaiian earth ovens, known as an "imu", combine roasting and steaming in a method called "kālua". A pit is dug into earth and lined with volcanic rocks and other rocks that do not split

neg: Hollow Earth Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia. Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France, Staffordshire in England, Montreal in Canada, Hangchow in China, and the Amazon Rainforest. Instead of saying that humans live on the outside surface of a hollow planet—sometimes called a "convex" Hollow Earth hypothesis—some have claimed humans live on the "inside" surface of a hollow spherical world, so that our universe

neg: Age of the Earth Earth is difficult to determine. It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages. Studies of strata, the layering of rocks and earth, gave naturalists an appreciation that Earth may have been through many changes during its existence. These layers often contained fossilized remains of unknown creatures, leading some to interpret a progression of organisms from layer to layer. Nicolas Steno in the 17th century was one of the first naturalists to appreciate the connection between fossil remains and strata.

neg: Moon rock in hydrated minerals common in Earth rocks. In some regards, lunar rocks are closely related to Earth's rocks in their isotopic composition of the element oxygen. The Apollo moon rocks were collected using a variety of tools, including hammers, rakes, scoops, tongs, and core tubes. Most were photographed prior to collection to record the condition in which they were found. They were placed inside sample bags and then a "Special Environmental Sample Container" for return to the Earth to protect them from contamination. In contrast to the Earth, large portions of the lunar crust appear to be composed of rocks

neg: Geologic record Geologic record The geologic record in stratigraphy, paleontology and other natural sciences refers to the entirety of the layers of rock strata — deposits laid down by volcanism or by deposition of sediment derived from weathering detritus (clays, sands etc.) including all its fossil content and the information it yields about the history of the Earth: its past climate, geography, geology and the evolution of life on its surface. According to the law of superposition, sedimentary and volcanic rock layers are deposited on top of each other. They harden over time to become a solidified (competent) rock column, that may

neg: Glossosomatidae to the surface. Inside is a pharate (young, unsclerotized) adult that will emerge and undergo sclerotization. Adults normally do not feed, but some species are known to feed on nectar. They can be found flying around at night, because they are nocturnal, and can be caught using light traps. Otherwise, adults can be found during the day inside of vegetation where they remain quiescent until night. After mating, eggs are lain in a gelatinous mass under rocks, on the water surface, or on floating objects in a stream. This gelatinous mass helps to protect the eggs by ensuring they do

neg: Devachan level of initiation (the vast majority of the inhabitants of Earth) go to Summerland (located on the astral plane only a few miles above the surface of Earth) when they die, those who have reached the first, second, or third levels of initiation go to Devachan when they die. The final Heaven where souls at the fourth level of initiation (those souls who have become arhats and no longer need to reincarnate) is called Nirvana. When reaching the fourth level of initiation, one can become a pratyekabuddha and enter Nirvana right away, or become a buddha or bodhisattva and teach

neg: Thickness (geology) Thickness (geology) Thickness in geology and mining refers to the distance across a packet of rock, whether it be a facies, stratum, bed, seam, lode etc. Thickness is measured at right angles to the surface of the seam or bed and thus independently of its spatial orientation. The concept of thickness came originally from mining language, where it was used mainly to indicate the workability of seams. It has since become an established term in earth science, for example in geology, for the depth of sedimentary rocks, in hydrogeology for the vertical extent of groundwater – i.e. the distance from

neg: Joseph Barrell sediment on the surface of the earth or under the ocean had been produced by weathering. Barrell's approach to scientific questions was to collect all evidence, generate multiple hypotheses and argue through all hypotheses to look for consistency or the lack of it in explaining other observations. An example of his original thinking was in his examination of the evolution of air-breathing in fishes in the light of evidence for climatic and environmental changes. Joseph Barrell Joseph Barrell (December 15, 1869 – May 4, 1919) was an American geologist who developed many ideas on the origins of the Earth, isostasy

neg: Plutonism the appearance of the word "plutonism" to 1842. Abbé Anton Moro, who had studied volcanic islands, first proposed the theory before 1750, and James Hutton subsequently developed it as part of his "Theory of the Earth", published in 1788. The idea contested Abraham Werner's neptunist theory which proposed that the Earth had formed from a mass of water and suspended material which had formed rocks as layers of deposited sediment which became the continents when the water retreated, further layers being deposited by floods and some volcanic activity. Plutonists strongly disputed the neptunist view that rocks had formed by processes

neg: Theory of the Earth evidence of the past action of processes which still operate today. He also anticipated natural selection, as follows: Hutton's prose hindered his theories. John Playfair in 1802 restated of Huttton's geological ideas in clearer English. However, he left out Hutton's thoughts on evolution. Charles Lyell in the 1830s popularised the idea of an infinitely repeating cycle (of the erosion of rocks and the building up of sediment). Lyell believed in gradual change, and thought even Hutton gave too much credit to catastrophic changes. Hutton's work was published in different forms and stages: Theory of the Earth Theory of the Earth

neg: Lamont–Doherty Earth Observatory 80 and 90 Ph.D. students are working towards degrees in specialties that include aqueous geochemistry, atmospheric science, climate science, ecophysiology, geology, paleoclimatology, paleontology, physical oceanography, solid Earth geophysics, and solid Earth geochemistry. Specific programs at Lamont–Doherty are conducted with many education-affiliates at Columbia and elsewhere in the New York metro area.. The Lamont–Doherty Core Repository is both an archive of sediment and rocks from on and beneath the ocean floor and an archive of digital data pertaining to the material. The repository contains more than 7,200 meters of core, from every ocean and sea, and many other samples. They are

neg: Porosity between larger particles). The graphic illustrates how some smaller grains can effectively fill the pores (where all water flow takes place), drastically reducing porosity and hydraulic conductivity, while only being a small fraction of the total volume of the material. For tables of common porosity values for earth materials, see the "further reading" section in the Hydrogeology article. Consolidated rocks (e.g., sandstone, shale, granite or limestone) potentially have more complex "dual" porosities, as compared with alluvial sediment. This can be split into connected and unconnected porosity. Connected porosity is more easily measured through the volume of gas or liquid that

neg: Soil weathering, while minerals formed at low temperature and pressure environment of the surface are more resistant to weathering. Weathering is usually confined to the top few meters of geologic material, because physical, chemical, and biological stresses and fluctuations generally decrease with depth. Physical disintegration begins as rocks that have solidified deep in the Earth are exposed to lower pressure near the surface and swell and become mechanically unstable. Chemical decomposition is a function of mineral solubility, the rate of which doubles with each 10 °C rise in temperature, but is strongly dependent on water to effect chemical changes. Rocks that

neg: Extrusive rock instead becoming a natural glass or obsidian. If the magma contains abundant volatile components which are released as free gas, then it may cool with large or small vesicles (bubble-shaped cavities) such as in pumice, scoria, or vesicular basalt. Examples of extrusive rocks include basalt, rhyolite, andesite, obsidian and pumice. Extrusive rock Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff.This is as opposed to intrusive rock formation, in

neg: Mountain lakes. Plateau mountains, such as the Catskills, are formed from the erosion of an uplifted plateau. In earth science, "erosion" is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transport it away to another location (not to be confused with weathering which involves no movement). The particulate breakdown of rock or soil into clastic sediment is referred to as "physical" or "mechanical" erosion; this contrasts with "chemical" erosion, where soil or rock material is removed from an area by its dissolving

neg: Witwatersrand Basin was alternating red and gray layers of mud which, when consolidated, became banded ironstones. As the sea deepened finer grained and muddy sediments accumulated. But changing geographical conditions resulted in the accumulation of a wide variety of sediments, ranging from mud, to sand, to gravel, and banded ironstones. Tillite deposits, dating from 2950 million years ago, are indicative of the first glaciation episodes on earth. Within 60 million years, up to 4500 m of sediment had accumulated on the granite base, to become the “West Rand Group” of rocks that contribute over 60% of the total thickness of the Witwatersrand

neg: Witwatersrand water, producing insoluble red iron oxide (rust), which precipitated out during the daylight hours. At night these reactions stopped. The result was alternating red and gray layers of mud which, when consolidated, became banded ironstones. Fluctuating sea levels resulted in the accumulation of a further variety of sediments, ranging from mud, to sand, to gravel, and banded ironstone. Tillite deposits, dating from 2.95 billion years ago, are indicative of the first glaciation episodes on earth. Within 60 million years, of sediment had accumulated on the granite base, to become the “West Rand Group” of rocks that contribute over 60% of

neg: Mineralogy of Mars is somewhere between the basalt or andesite rocks on Earth. This led to the formation of minerals similar to what is found on Earth. The presence of iron oxide gives the surface the “rust” color that is associated with Mars, the Red Planet. The presence of perchlorate, in high percentages, forms highly saline soils, which could produce liquid water. Chemical alteration of Martian rocks into carbonate and phyllosilicate minerals occurred earlier in Mars history when water was present in large quantities. Orbital instruments and Landers not only identified new minerals but in some cases also confirmed the presence of minerals

neg: Mr. Adam radiation was released. The radiation caused all men on Earth to become sterile, even boys who were still inside the mother's womb. However, ten months after the explosion in Mississippi, a doctor delivers a perfectly healthy baby girl. It's soon discovered that the child's father, who has the surname "Adam", was more than a mile under the surface of Earth inside an old silver and lead mine during the explosion. It would appear that Mr. Adam is humanity's only hope to stave off extinction. Mr. Adam Mr. Adam (1946) is the first novel written by Pat Frank, dealing with the

neg: Scientific drilling Scientific drilling is used to address a wide range of problems, which cannot be addressed using rocks exposed on the surface or on the seafloor. The Integrated Ocean Drilling Program has a broad set of research objectives, which can be divided into three principal themes: ICDP focuses on scientific drilling to address the following questions about the history, chemistry, and physics of Earth and the biosphere: The Kola Superdeep Borehole on the Kola peninsula of Russia reached and is the deepest penetration of the Earth's solid surface. The German Continental Deep Drilling Program at has shown the earth crust to

neg: Geographical centre of Earth Geographical centre of Earth The geographical centre of Earth is the geometric centre of all land surfaces on Earth. In a more strict definition, it is the superficial barycenter of the mass distribution produced by treating each continent or island as a region of a thin shell of uniform density and approximating the geoid with a sphere. The centre is inside Earth but can be projected to the closest point on the surface. In 1864, Charles Piazzi Smyth, Astronomer Royal for Scotland, gave in his book "Our Inheritance in the Great Pyramid" the coordinates with , the location of the

neg: Jack Hills and the resultant sediment deposited as sedimentary rock. The zircons and various aspects of their geochemistry provide evidence for the existence of continental-type crust on the surface of the earth during the Hadean eon, contrasting with earlier ideas on the earliest phase of Earth's history. Additionally, oxygen isotopic ratios in the zircons provide evidence for the presence of liquid water on the surface, if not a water ocean; also contrasting with earlier ideas on Earth's history. The theory of humid and cool conditions before the Late Heavy Bombardment has been promoted as Cool Early Earth. The Jack Hills banded iron

neg: Lamont–Doherty Earth Observatory seafloor. To do so, they employ tools that include side-scan sonar and multi-channel seismic imaging to map the surface and sub-surface, as well as satellite-based remote sensing. An early success of MG&G researchers was the discovery of seafloor spreading, which led to the general acceptance of plate tectonics as the broad foundation for understanding earthquake generation. Other MG&G scientists study the interface between ice sheets and bedrock, sediment transport in the Hudson River, and meteorite impacts in the deep ocean. The Division of Ocean and Climate Physics (OCP) focuses on the links between Earth’s climate system and its oceans, including

neg: Sedimentary rock removes most deposited sediment shortly after deposition. That new rock layers are above older rock layers is stated in the principle of superposition. There are usually some gaps in the sequence called unconformities. These represent periods where no new sediments were laid down, or when earlier sedimentary layers were raised above sea level and eroded away. Sedimentary rocks contain important information about the history of the Earth. They contain fossils, the preserved remains of ancient plants and animals. Coal is considered a type of sedimentary rock. The composition of sediments provides us with clues as to the original rock. Differences

neg: Compression fossil plant structures do not preserve as well under compression. Typically, only the basic outline and surface features are preserved in compression fossils; internal anatomy is not preserved. These fossils may be studied while still partially entombed in the sedimentary rock matrix where they are preserved, or once lifted out of the matrix by a peel or transfer technique. Compression fossils are formed most commonly in environments where fine sediment is deposited, such as in river deltas, lagoons, along rivers, and in ponds. The best rocks in which to find these fossils preserved are clay and shale, although volcanic ash may

neg: Schiehallion experiment of this, or . In comparison with the modern accepted figure of , the density of the Earth had been computed with an error of less than 20%. That the mean density of the Earth should so greatly exceed that of its surface rocks naturally meant that there must be more dense material lying deeper. Hutton correctly surmised that the core material was likely metallic, and might have a density of . He estimated this metallic portion to occupy some 65% of the diameter of the Earth. With a value for the mean density of the Earth, Hutton was able

neg: Post-glacial rebound that concerning seashores, but occur above sea level. Tilting of land will also affect the flow of water in lakes and rivers in the future, and thus important for water resource management planning. Ice, water and mantle rocks have mass, and as they move around, they exert a gravitational pull on other masses towards them. Thus, the gravity field, which is sensitive to all mass on the surface and within the Earth, is affected by the redistribution of ice/melted water on the surface of the Earth and the flow of mantle rocks within. Today, more than 6000 years after the

neg: Peak District Coal Measures rocks on the eastern and western margins, Carboniferous Limestone at the core and with rocks of Millstone Grit outcropping between them. The southern edge of the dome is overlain by sandstones of Triassic age though they barely impinge on the National Park. The White Peak is the central and southern section where Carboniferous Limestone is found at or near the surface. The Dark Peak to the north, east and west is characterised by Millstone Grit outcrops and broad swathes of moorland. Earth movements after the Carboniferous period resulted in the up-doming of the area and, particularly in the

neg: Salton Buttes Salton Buttes. It is one of the largest and warmest on Earth, with temperatures of at depth. Various volcanic rocks have been found in drill cores at the Salton Buttes. Rocks found include andesite, basalt, dacite, diabase, gabbro and rhyolite. Some of these volcanic rocks bear traces of hydrothermal alteration. In some places the layers of volcanic rocks are as thick as . There may be other volcanoes buried in the sediment pile; at least four separate aeromagnetic anomalies have been found at the Salton Buttes, and these may be signs of buried volcanoes. Since the Pliocene, the Salton Trough

neg: Optically stimulated luminescence thermochronometry the most likely cooling histories undergone by the mineral. Bedrock samples from earth surface or boreholes are required earth materials for OSL dating. Minerals (quartz and/or feldspar) are usually separated from the rock or sediment samples under regulated laboratory lighting system similar to procedures used in archaeological OSL dating. The light source is usually a controlled red light condition to avoid luminescence signal resetting. Crushing of sample are gently carried out to avoid generating heat that is strong enough to reset OSL signal in the minerals. Crushed samples are separated by means of a sieve to get fine-grained. A range

neg: Post-glacial rebound determined by two factors: the viscosity or rheology (i.e., the flow) of the mantle, and the ice loading and unloading histories on the surface of Earth. The viscosity of the mantle is important in understanding mantle convection, plate tectonics, dynamical processes in Earth, the thermal state and thermal evolution of Earth. However viscosity is difficult to observe because creep experiments of mantle rocks take thousands of years to observe and the ambient temperature and pressure conditions are not easy to attain for a long enough time. Thus, the observations of postglacial rebound provide a natural experiment to measure mantle rheology.

neg: Interplanetary contamination samples we already have. Another consideration is the difficulty of keeping the sample completely free from Earth life contamination during the return journey and during handling procedures on Earth. This might make it hard to show conclusively that any biosignatures detected does not result from contamination of the samples. Instead they advocate sending more sensitive instruments on Mars surface rovers. These could examine many different rocks and soil types, and search for biosignatures on the surface and so examine a wide range of materials which could not all be returned to Earth with current technology at reasonable cost. A sample-return

neg: Meteorite now more than 30,000 meteorite finds in the world's collections started with the discovery by Harvey H. Nininger that meteorites are much more common on the surface of the Earth than was previously thought. Nininger's strategy was to search for meteorites in the Great Plains of the United States, where the land was largely cultivated and the soil contained few rocks. Between the late 1920s and the 1950s, he traveled across the region, educating local people about what meteorites looked like and what to do if they thought they had found one, for example, in the course of clearing a

neg: Intrusive rock formed from magma that cools and solidifies within the crust of the planet. In contrast, an "extrusion" consists of extrusive rock; rock formed above the surface of the crust. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons. Plutonic rocks form 7% of the Earth's current land surface. Coarse-grained intrusive igneous rocks that form at depth within the earth are called "abyssal" while those that form near the surface are called subvolcanic or "hypabyssal". Intrusive structures are often classified according to whether or not they are parallel to the bedding planes

neg: John Perry (engineer) challenging Kelvin's assumption of low thermal conductivity inside the Earth, and thus disputing Kelvin's estimate that the Earth was only 20–400 million years old, but this had little impact. It was not until the discovery in 1903 that radioactive decay releases heat and the development a few years later of radiometric dating of rocks that it was accepted that the age of the earth was many times older, as Perry had argued. Perry's reasoning held that if the interior of the Earth was fluid, or partly fluid, it would transfer heat much more effectively than the conductivity which Kelvin assumed,

neg: James Hays James Hays James D. Hays is a professor of Earth and environmental sciences at Columbia University's Lamont-Doherty Earth Observatory. Hays founded and led the CLIMAP project, which collected sea floor sediment data to study surface sea temperatures and paleoclimatological conditions 18,000 years ago. Hays is probably best known as a co-author of the 1976 paper in "Science", "Variations in the Earth's orbit: Pacemaker of the ice ages." Using ocean sediment cores, the "Science" paper verified the theories of Milutin Milanković that oscillations in climate can be correlated with Earth's orbital variations of eccentricity, axial tilt, and precession around the Sun

neg: Dhole a territorial function is unlikely, as faeces are mostly deposited within the clan's territory rather than the periphery. Faeces are often deposited in what appear to be communal latrines. They do not scrape the earth with their feet, as other canids do, to mark their territories. Four kinds of den have been described; simple earth dens with one entrance (usually remodeled striped hyena or porcupine dens); complex cavernous earth dens with more than one entrance; simple cavernous dens excavated under or between rocks; and complex cavernous dens with several other dens in the vicinity, some of which are interconnected. Dens

neg: Terrestrial planet Terrestrial planet A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth ("Terra" and "Tellus"), as these planets are, in terms of structure, "Earth-like". Terrestrial planets have a solid planetary surface, making them substantially different from the larger giant planets, which are composed mostly of some combination of hydrogen, helium, and water existing in various

neg: Death Valley National Park later exposed these rocks to nearly 500 million years of erosion. The Proterozoic sedimentary formations of the Pahrump Group were deposited on these basement rocks. This occurred following uplift and erosion of any earlier sediments from the Proterozoic basement rocks. The Pahrump is composed of arkose conglomerate (quartz clasts in a concrete-like matrix) and mudstone in its lower part, followed by dolomite from carbonate banks topped by algal mats as stromatolites, and finished with basin-filling sediment derived from the above, including possible glacial till from the hypothesized Snowball Earth glaciation. The very youngest rocks in the Pahrump Group are basaltic

neg: Ice age North Sea, connecting the British Isles to Continental Europe. The redistribution of ice-water on the surface of the Earth and the flow of mantle rocks causes changes in the gravitational field as well as changes to the distribution of the moment of inertia of the Earth. These changes to the moment of inertia result in a change in the angular velocity, axis, and wobble of the Earth's rotation. The weight of the redistributed surface mass loaded the lithosphere, caused it to flex and also induced stress within the Earth. The presence of the glaciers generally suppressed the movement of faults

neg: Thor: The Dark World right person to make a great "Thor" out of the story they wanted to do." Jenkins had intended to create a film based on the premise of "Romeo and Juliet", where Jane was stuck on Earth with Thor forbidden to come save her. After Thor eventually does travel to Earth, he and Jane would have discovered that Malekith was "hiding the dark energy inside of Earth because he knows that Odin doesn't care about Earth, and so he's using Odin's disinterest in Earth to trick him." Three days later, it was reported that Marvel was looking at Alan Taylor and

neg: Volcanic rock While still dominated by silicates, more primitive volcanic rocks have mineral assemblages with less silica, such as olivine and the pyroxenes. Bowen's reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks. Occasionally, a magma may pick up crystals that crystallized from another magma; these crystals are called xenocrysts. Diamonds found in kimberlites are rare but well-known xenocrysts; the kimberlites do not create the diamonds, but pick them up and transport them to the surface of the Earth. Volcanic rocks are named according to both their chemical composition and texture. Basalt is a very

neg: Hollow Earth a tunnel in the mountain of "Mashu", entered a subterranean garden. In Celtic mythology there is a legend of a cave called "Cruachan", also known as "Ireland's gate to Hell", a mythical and ancient cave from which according to legend strange creatures would emerge and be seen on the surface of the Earth. There are also stories of medieval knights and saints who went on pilgrimages to a cave located in Station Island, County Donegal in Ireland, where they made journeys inside the Earth into a place of purgatory. In County Down, Northern Ireland there is a myth which says

neg: Earthrise over the Moon's surface. An earthrise that might be witnessed from the "surface" of the Moon would be quite unlike moonrises on Earth. Because the Moon is tidally locked with the Earth, one side of the Moon always faces toward Earth. Interpretation of this fact would lead one to believe that the Earth's position is fixed on the lunar sky and no earthrises can occur; however, the Moon librates slightly, which causes the Earth to draw a Lissajous figure on the sky. This figure fits inside a rectangle 15°48' wide and 13°20' high (in angular dimensions), while the angular diameter

neg: Jake Matijevic (rock) consistent with feldspar, such as sodium, aluminum and potassium, and lower concentrations of magnesium, iron and nickel than other such rocks previously found on Mars. The mineral content and elemental abundance indicates "Jake M" rock may be a mugearite, a sodium rich oligoclase-bearing basaltic trachyandesite. Igneous rocks similar to the "Jake M" rock are well known but occur rarely on Earth. On Earth, such rocks form when magma, usually found in volcanoes, rises to the surface, cools and partially solidifies with certain chemical elements, while the warmer liquid magma portion becomes enriched with the left-behind elements. By remarkable coincidence, the

neg: Mars Exploration Rover one Martian year anniversary (669 sols or 687 Earth days) on November 20, 2005. "Opportunity" celebrated its anniversary on December 12, 2005. At the beginning of the mission, it was expected that the rovers would not survive much longer than 90 Martian days. The Columbia Hills were "just a dream", according to rover driver Chris Leger. "Spirit" explored the semicircular rock formation known as Home Plate. It is a layered rock outcrop that puzzles and excites scientists. It is thought that its rocks are explosive volcanic deposits, though other possibilities exist, including impact deposits or sediment borne by wind or

neg: Earth radius 1998 the bulge has increased, possibly due to redistribution of ocean mass via currents. The variation in density and crustal thickness causes gravity to vary across the surface and in time, so that the mean sea level differs from the ellipsoid. This difference is the "geoid height", positive above or outside the ellipsoid, negative below or inside. The geoid height variation is under on Earth. The geoid height can change abruptly due to earthquakes (such as the Sumatra-Andaman earthquake) or reduction in ice masses (such as Greenland). Not all deformations originate within the Earth. The gravity of the Moon and