Precambrian.............................................................................................................................................................................................................Précambrien

Pré-Câmbrico / Pre-Cámbrico / Präkambrium / 前寒武纪 / Докембрийский / Precambriano /

Informal term that includes all geological time from the beginning of Earth's history to the beginning of the Cambrian period, that is, up to about 570 Ma (millions of years ago). For certain geoscientists, the Precambrian includes three eons: (i) Priscoan* (from the formation of the Earth to about 4000 Ma) ; (ii) Archean, between 4,000 Ma and 2,500 Ma and (iii) Proterozoic, between 2,500 and 590 Ma.

See: « Geological Time Scale »
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« Eon »
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« Geological Time »

Earth formed at about 4.5 Ga (4.5 billion years ago), but almost 4.0 My (4.0 billion years) passed until the first animals appeared. It is this interval of time that the geoscientists call Precambrian. Some geoscientists avoid this term and prefer to consider, prior to the Phanerozoic, three Eons (Harland et al., 1982): (i) Proterozoic ; (ii) Archean and (iii) Priscoanian. But the names of the periods and epochs that compose these eons do not have international status and vary from one geoscientist to another. The paleogeographic sketch illustrated in this figure (Late Precambrian ± 600 Ma), for certain geoscientists, corresponds to the paleogeography of the Vendian Period, which is part of the Rifean era of the Proterozoic eon. Anyway, speaking of the Precambrian as a mere time-interval is misleading because it encompasses about 7/8 of Earth's history. During this time interval the most important geological and biological events of the Earth's history occurred: (i) Earth formed ; (ii) Life appeared ; (iii) The first lithospheric plates formed and began to move relative to each other (plate tectonics) ; (iv) Eukaryotic cells (also called eukaryotes) have appeared and evolved ; (v) The atmosphere was enriched in oxygen and (vi) The multicellular organisms, including the first animals appeared. At the end of the Precambrian, almost the entire continental mass was agglutinated and formed the supercontinent Pre-Pangea or Rodhinia, which, as shown above, was located almost, entirely, in the southern hemisphere. The great ocean that surrounded the Pre-Pangea was the Panthalassa. Sea level was low, since volume of ocean basins was very large, because most oceanic mountains (oceanic ridges induced by oceanic expansion) were swallowed by B-type subduction zones. The volume of water, in all its forms, has been considered constant since the Earth's formation (around ± 4.5 Ga).

(*)  Harland, W. B., coined the Hadean as Priscoan period, that is to say, the geologic eon of the Earth predating the Archean. It began with the formation of the Earth  about 4.6 billion years ago and ended, as defined by the International Commission on Stratigraphy, 4 billion years ago.

Precession..............................................................................................................................................................................................................................Précession

Precessão / Precesión / Präzession / 岁差 / Прецессия / Precessione /

Conical motion of an axis of rotation, like what the axis of rotation of the Earth does, perpendicularly, to the plane of the orbit. Orbital eccentricity, precession, and changing the inclination of the Earth's axis influence the distribution of solar radiation reaching the Earth's atmosphere by increasing or decreasing seasonal differences and hence their contribution to sea level changes.

See : « Astronomic Theory of Paleoclimate »
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« Milankovitch's Cycle »
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« Equinoxial Precession »

In astronomy, the term precession refers to a continuous and slow change of the axis of rotation of a celestial body or the plane of its orbit, induced by gravity. Every time we speak of precession, it is important to specify whether it is the precession of the axis of a celestial body, such as the Earth's axis, or whether it is the precession of the orbit of that body around another celestial body, with the orbit of the Earth around the Sun. The precession of the axis of rotation of the Earth, refers to the conical movement, which the axis makes around it like what one observes when a spinning top. The precession movement of the Earth's axis lasts about 26,000 years. The term precession of the axis of rotation of the Earth typically refers to secular motion, although there are other movements of lesser amplitude of the earth's axis as the notation (irregular movement of the axis of rotation of an object, axially, symmetrical, a gyroscope or the Earth) and the polar movement (movement of the Earth axis of rotation through its surface). The precession of the Earth's axis has historically been called the precession of the equinoxes. The term equinox, which derives from the Latin æquinoctium, and means night equal (æquus, equal, and nox, noctis, night) can be defined as the instant in which the Sun, in its apparent orbit, crosses the celestial equator. The line of the terrestrial equator projected on the celestial sphere or firmament, where all the objects visible in the sky can be projected, because the equinoxes ** move westward, relative to the fixed ecliptic (celestial bodies that do not move relative to other stars), as opposed to the movement of the Sun along the ecliptic (apparent trajectory that draws the Sun in the sky for a year). An equinox occurs twice a year, when the inclination of the axis of rotation does not incline neither towards the Sun nor in the opposite direction. When the Sun is vertically above the equator, as illustrated in the diagrams of this figure and figure below, it can be said that the Earth rotation axis shifts as the axis of rotation of a spinning top. During a complete rotation, which lasts about 26,000 years, the Earth rotation axis is oriented towards different points. Considering that in astronomy, a polar star is usually a star visible at naked eye, which is, more or less, in line with the rotation axis of a planet and that the direction of the axis of rotation of an object celestial changes, continuously over time, due to the precession phenomenon of the equinoxes, the corresponding polar star changes with time (in long term, the stars themselves move relative to each other, and this movement is another cause of change of the polar star in many precession cycles). Thus, at present, the star Polaris (commonly called the Northern Star or Polar Star, which is the brightest star in the constellation** of the Little Bear or Ursa Minor) gives us, roughly, the North Earth pole (in the Southern Hemisphere, it is admitted that the Beta Hydri star of the constellation Hydrus is a better candidate, since its apparent magnitude is, easily, noticeable). However, about 3 000 years ago, the polar star was Thuban star or Alpha Draconis (star or star system in the Dragon constellation, which is relatively easy to locate due to its positioning in relation to Ursa Major ***. In the same way, it is understood that within 14,000 years, the polar star will Vega star (Alpha star of the constellation Lira, which is relatively close to the Solar System). The cycle of precession movement of the Earth's axis is reduced by a slower rotation of the Earth's elliptical orbit in the opposite direction. The combination of these two movements produces a displacement or precession of the equinoxes every 23 ky.

(*) There are two equinoxes occurring during the months of March and September, when the sun's light strikes on the Northern Hemisphere and the Southern Hemisphere)

(**) Although some people think otherwise, there is no physical relationship between the stars and other constituents of a constellation. However, when on a starry night a geoscientist looks at the sky, he has no perception of the distances of the stars to the Earth, but only an idea of their disposition relative to the others in the firmament. That is why many people have the impression that all stars, nebulae, galaxies and other celestial objects are all the same distance from Earth and close to each other.

(***) The Great Ursa, which is detected by direct observation, is one of the most well-known constellations in the northern hemisphere. Seven stars stand out clearly from the others and are visible throughout the year in all areas located above 40 ° north latitude: (i) Dubhe (σ UMa), Merak (β UMa), Phecda (γ UMa), Megrez (δ UMa), Alioth (ε UMa), Mizar (ζ UMa) and Alkaid (η UMa) (https://fr.wikipedia.org/ wiki / Grande_Ourse).

Precipitate (Chemistry)....................................................................................................................................................................Précipitât (Chimique)

Precipitado / Precipitado (químico) / Präzipitat / 沉淀 / Преципитат (осадок) / Precipitato (chimica) /

Solid formed by precipitation (chemical or biochemical reaction), either in a solution or inside another solid.

See: « Precipitation (chemistry) »
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« Reef »
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« Deposition (carbonates) »

A precipitate is a solid which forms from a solution. A common example is the mixing of two clear solutions: (1) Silver nitrate (AgNO₃) and (2) Sodium chloride (NaCl). The precipitate forms because the ClAg solid is insoluble in water. This is true for all precipitates, which are solids insoluble in aqueous solutions. Sometimes the house pipes are clogged by precipitates of magnesium and calcium oxides deposited in the pipes. This can happen with hard water (with salts dissolved in more than 5%). Another example of precipitates are the kidney stones, which are almost always calcium ions and oxalates. This is why it is often suggested that a good way to avoid kidney stones is to drink plenty of water because this increases the solubility of the precipitate, that is, of the stones. Rocks formed by precipitated material, such as certain carbonates, evaporites, concretions, etc., are, easily, distinguished from other sedimentary, metamorphic or igneous rocks, as suggested in this figure which illustrates the Orakei Korako thermal area, near Lake Ohakuri, which is, probably, one of the best thermal areas in New Zealand and the world. The light spots correspond to enormous masses of precipitates that exhibit very varied colours, which contrast with the colour of the surrounding rocks. A mineral can precipitate from a solution of water in the pores or other openings of the rocks either by a chemical reaction with the surrounding rocks, either by a change of pressure or temperature or even just evaporation. The quartz veins that sometimes cross the igneous rocks are common products of a mineral precipitate. In the same way many concretions, which are geological structures still poorly understood and often confused with fossil eggs, turtle shells or bones, are geological phenomena very common in all types of sedimentary rocks, either in sandstones, shales, siltstones, and limestones) appear to form as minerals precipitated in fractures and cavities or as sedimentary constructions at successive levels around a nucleus such as a shell or a pebble.

Precipitation (Chemistry)..................................................................................................................................................Précipitation (Chimique)

Precipitação / Precipitación (química) / Niederschlag (chemischen) / 沉淀（化学） / Образование осадка (химия) / Precipitazioni (chimica) /

Formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion (in a solid). A precipitation can occur when the insoluble substance, the precipitate, is formed in the solution due to a chemical reaction or when the solution has been supersaturated by a compound.

See: « Precipitate (chemistry) »
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« Deposition (carbonates) »
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« Compensation Depth »

Precipitation is the formation of a solid during a chemical reaction. The solid formed in the chemical reaction is called a precipitate. This can occur when the insoluble substance, the precipitate, is formed in the solution due to a chemical reaction or when the solution has been supersaturated by a compound. The formation of the precipitate is a sign of chemical change. Most of the time, the formed solid exits the phase and sinks to the bottom of the solution (however it will float if it is less dense than the solvent, or form a suspension). Such a reaction is useful not sedimentology and has many industrial and scientific applications whereby the chemical reaction can produce a solid which will be collected from the solution by filtration, decantation or centrifugation. An important stage of the precipitation process is the beginning of nucleation (the process by which nuclei are usually formed in solution; the term nucleus as used herein is defined as the smallest aggregate of the solid phase of atoms, molecules, or is formed during a precipitation and is capable of growth spontaneously). The creation of a hypothetical solid particle includes the formation of a surface, which requires energy based on the surface energy ratio of the solid and the solution. If such energy is not available, and no suitable nucleation surface is available, supersaturation occurs (solution containing more dissolved material than could be dissolved by the solvent under normal circumstances). This photograph illustrates the deposition of evaporites by precipitation in the Dead Sea. The sedimentary textures of halite suggest that it is usually deposited rapidly in the form of large transparent crystals and that impurities are introduced when ambient conditions change and halite deposition stops momentarily. In shallow water, halite precipitates at the bottom of the brine in the form of a crystalline crust that on average is no more than an inch thick.

Principle of Carbonate Bucket................................................................................Principe du seau carbonaté

Princípio do balde carbonatado / Principio de balde carbonático / Bucket Prinzip / 木桶原理 / Принцип карбонатного сегмента / Principio secchio calcareo /

The growth of a rimmed (or fringed) carbonate platform is, primarily, determined by the potential growth of its halo. Synonym with Carbonated Bucket.

See : « Bioherm »
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« Deposition (carbonates) »
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« Geological Principle »

The architecture of the growth of a rimmed carbonated platform resembles the geometry of a bucket or inverted cone trunk, with the mouth wider than the bottom. The carbonate platform is sustained either by the rigid reef-like borders or by the rapid cementing of the shallow sands or by the filling of unconsolidated sedimentary particles of the lagoon or the tidal plain. According to W. Schlager, three basic concepts have to be taken into account in carbonate sedimentation: (a) Carbonates are, mainly, of organic origin ; (b) Carbonates build structures resistant to sea waves and (c) Carbonates undergo an intense diagenetic change, since the original minerals are metastable. Five main types of carbonate platforms are, generally, considered: A) Rimmed Platforms ; B) Ramp Platforms ; C) Epeirial (or epíric) platforms ; D) Isolated Platforms ; E) Dead or Drowned Platforms. Rimmed platforms are characterized by the presence of reefs or calcareous sand from shallow (carbonated sandbanks covered by shallow sea water) on the edge of the platform and sands clay in the lagoon or on the open platform. This type of platform forms in calm waters and its extension varies between 10 and 100 km. Ramp Platforms, in which the carbonated sands of the shoreline pass, at the base of the ramp, to clay sands and deep-water muds, are platform in which the reefs are rare and the width of the ramp can reach 100 km. Epeirial (or epíric) platforms are characterized by the presence of tidal surfaces and protected lagoons. The width of an epeiric platform can reach 10,000 km. Isolated Platforms. the facies (lithologies) are very controlled by the orientation of the prevailing winds. These platforms have sandy reefs and bodies, such as the rimmed platform, in the windward margin (the margin facing the side from where the wind blows), but in the leeward margin (margin in direction to where the wind blows), the sediments are more muddy. An isolated platform can reach 100 km wide. Dead or drowned platforms are below the photic zone (where there is insufficient light for photosynthesis, i.e. when glucose (C₆H₁₂O₆) is obtained from carbon dioxide (CO₂) and water (OH₂) through the energy of sunlight). The most well known carbonate platform geometry is associated with tropical manufacturing processes, where carbonate platforms can be subdivided into three main sedimentary environments: A) Reef, which is the part of the carbonate platform created in situ by sessile organisms ; B) Internal Lagoon (part of the platform behind the reef, which is characterized by shallow and calm waters with sediments composed of fragments of reefs and hard parts of organisms or terrigeneous sediments when the reef is epicontinental) and C) Reef Slope that connects the reef to the basin and acts as a sink for the excess carbonate sedimentary particles, although most of the sediment produced in the lagoon and the reef is transported by various processes and accumulated on the slope. Besides this principle, in Geology there are many others, among which we can mention: (i) Principle of Composition, a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of Original Lateral Continuity, the sedimentary layers settle down in lateral continuity ; (iii) Principle of Original Horizontality, the sedimentary layers deposit horizontally (not totally true) ; (iv) Principle of Intersection, the most recent dyke move the oldest dykes ; (v) Principle of Intrusion, an igneous intrusive rock is younger than the rock it penetrates ; (vi) Principle of Superposition, in a slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers above ; (vii) Principle of Ochkam, plurality should not be invoked without necessity ; (viii) Goguel's principle, during the deformation, the volume of the sediment remains. more or less, constant ; (ix) Walther's Principle, in conforming strata, vertically, succeeding facies occur, laterally, in adjacent environments ; (x) Dextrological Principle, if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) Principle of Uniformitarianism, geological changes are due, mainly, to the same processes and continuous changes that are observed today: "The Present is the key of the Past" ; (xii) Principle of Fossil Succession, the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (xiii) Principle of Catastrophism, changes that occurred on Earth were due to the occurrence of major natural disasters ; (xiii) Principle of the Continental Drift, the continental masses have a small density and, for this reason, floated on the dense masses of ocean, moving and changing the surface of the planet ; (xiv) Principle of Plate tectonics, it is not the continents that move, but the lithospheric plates that contain these continents, etc.

Principle of Catastrophism..............................................................................................Principe du catastrophisme

Princípio de catastrofismo / Principio de catastrofismo / Prinzip der Katastrophismus / 对灾变原理 / Теория катастроф / Principio di catastrofismo /

Hypothesis that the Earth, during its history, was affected by violent, sudden, short-lived events, eventually, on a global scale. This hypothesis, formulated by George Cuvier, explains the geological and biological changes that occurred on our planet were produced by sudden and violent changes,i.e., by catastrophes.

See : « Geological Principle »
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« Uniformitarianism Principle »
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« Tsunami »

Before 1850, most humans thought that Earth was, relatively, young and that the processes and forms of relief occurring on Earth were the result of catastrophic events (such as Creation and the Flood) that occurred very rapidly (principle Catastrophism). However, detailed observations of the processes taking place on Earth led certain geoscientists such as James Hutton and Charles Lyell to advance the hypothesis that the processes that can be observed today are the same ones that have operated throughout the history of the planet. This allowed them to advance the concept of Uniformitarianism, often referred to as "The Present is the key to the Past." The most modern way of asserting this principle is the conjecture that the laws of nature have operated in the same way over time and that all geological processes must obey the laws of nature (laws of physics and chemistry). Initially one of the most difficult problems of applying this principle to Earth was the hypothesis that the rates of all geological processes had been the same over time. It is now known the Earth is much older (4.5 billion years) than was thought even in the nineteenth-twentieth centuries and that in the early days of its history it was much warmer than it is today. Thus, it is likely that the rates of some geological processes have changed over time. It has also been recognized that there may be rare catastrophic events that can cause very rapid changes on Earth. As these catastrophic events occur, infrequently, it is difficult to observe their effects, but it seems that they follow the laws of nature. As suggested in this figure, a meteor* collided with the Earth to the south with the Peruvian city of Puno, in the region of Carangas on September 16, 2007, causing a crater about 15 meters deep. This photograph was taken two days after impact.

(*) As long as the object is in the sky, it is called a "meteoroid". It is accompanied, during the crossing of the atmosphere, a luminous phenomenon: "meteor" . If it's big, we talk about "bolide". The object on the ground is named meteorite. (Terre de Météorites, EDP Sciences 2016, ISBN: 978-2-7598-1928-7)

Principle of Composition...........................................................................................................Principe de la composition

Princípio da composição / Principio da composición / Prinzip der Komposition / 组成原理 / Принцип композиции / Principio di composizione /

A rock represented by fragments in another rock is older than the rock that contains them.

See : « Geological Principle »
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« Relative Age »
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« Rock Cycle »

This principle says a rock is younger than its constituents. It applies to all types of rocks. A granite rock, for instance, is younger than the inclusions (xenoliths*) that it contains. A conglomerate is younger than its pebbles, which are, often, fragments of much older rocks. A volcanic rock, as illustrated in this figure (lava of Mount Vesuvius, Pompeii, Italy), is, always, younger than the xenoliths it contains, i.e., in this case, the limestone rock from which the block has been trapped in the lava. The limestone rock formed several tens of millions of years before the block was engulfed in lava. Although this geological principle is always valid for rocks, it is not, necessarily, true for minerals. A rock may contain minerals younger than it, since metasomas are very frequent in rocks that have undergone an important metasomatism**. In addition to this geological principle there are others, such as: (i) Principle of the Original Lateral Continuity, which says: the sedimentary layers deposit in lateral continuity ; (ii) Principle of the Original Horizontality, which states: the sedimentary layers deposit horizontally ; (iii) Principle of Intersection, which says the most recent dyke displace the oldest dykes ; (iv) Principle of Intrusion, which says an igneous intrusive rock is younger than the rock it penetrates ; (v) Principle of Superposition, which states: in a series of non or slightly deformed sedimentary layers, the oldest layers are at the bottom and the most recent ones above ; (vi) Principle of Fossil Succession, which says: the distribution of fossils is not unpredictable, it follows a definite vertical sequence ; (vii) Principle of Goguel, which says: during the deformation, the volume of the sediment is more or less constant ; (viii) Walther's Principle, which states: facies that succeed, vertically, in conforming strata, succeed laterally in adjacent environments ; (ix) Dextrological Principle, which says: if a reference system rotates in a clockwise direction the deflection (Coriolis effect) of an object is to the left ; (x) Principle of the Carbonated Bucket, which says: the growth of an edged platform is determined by the growth of the edge; (xi) Principle of Uniformitarianism; (xii) Principle of Ochkam, etc.

(*) Rock fragment that becomes enveloped in a larger rock during the latter's development and solidification. Xenolith is almost exclusively used to describe inclusions in igneous rocks during magma  emplacement and eruption.

(**)  Chemical alteration of a rock by hydrothermal  and other fluids.  It is the replacement of one rock by another of different mineralogical and chemical composition. The minerals which compose the rocks are dissolved and new mineral   formations are deposited in their place. Dissolution  and deposition occur simultaneously and the rock remains solid. (https://en.wikipedia.org/wiki/Metasomatism)

Principle of Fossil Succession......................................................Principe de la succession des fossiles

Principe de la succession des fossiles / Principio de sucesión fosilífera / Prinzip der Nachfolge von fossilen / 化石的继承原则 / Принцип последовательности образования ископаемых / Principio di successione di fossili /

The distribution of fossils in the rocks is not unpredictable, it follows a definite vertical sequence. William Smith proposed this principle at the end of the eighteenth century. It is interesting to note that the author of this principle never admitted the evolution of the species. Today, all geoscientists explain such a succession of fossils as a consequence of the evolution of species.

See : « Index Fossil »
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« Relative Age »
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« Geological Principle »

This principle, also called by certain geoscientists, Principle of Paleontological Identity, says that groups of fossils * (animal or plant) occur in the geological record in a determined and invariable order, so that, if this order is known, it is possible to determine the relative age between layers from their fossiliferous content. This principle was developed by geologist William Smith, who worked in Wales (c. 1800), where he developed the idea that every period of Earth's history has its own fossil record. During his work on canal construction, he found that rock sequences were always found in the same order of overlap and that each group of strata contained the same distinctive fossils throughout the country. He discovered that, although the lithologic composition of the strata varied, the same fossils were of the same age. He established the bases for the application of paleontology to geology, i.e., "Stratigraphic Paleontology", and concluded that the organisms had changed over time. He established the  bases of biostratigraphy using the fossils as a tool to characterize the stratigraphic intervals. The first principle, which was, initially used as a practical tool, was later explained by Darwin's theory of evolution. It was William Smith who proposed this principle at the end of XVIII century. .It is interesting to note that the author of this principle never admitted the evolution of the species. At the present time, all geoscientists explain such a succession of fossils as a consequence of the evolution of species, which postulates that the species that inhabited the Earth were not created, independently, but descend from one another and are interconnected by evolutionary links (this transformation, called evolution of species, was presented and explained by Charles Darwin in 1859 in his treatise "The Origin of Species). Do not forget that Geology and Paleontology are sciences and that Creationism is the religious belief that humanity, life, Earth and the Universe are the creation of a supernatural agent. The term Creationism is more used to refer the rejection, for religious reasons of certain biological processes, particularly evolution. Besides this principle, in Geology there are many other principles or hypotheses, among which we can mention: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Carbonated Bucket: the architecture of the growth of a fringed carbonate platform resembles the geometry of a bucket or inverted cone trunk ; (iii) Principle of Original Horizontality: the sedimentary layers deposit horizontally (not totally true) ; (iv) Principle of Intersection: the most recent dyke move the oldest dykes ; (v) Principle of Intrusion: an igneous intrusive rock is younger than the rock it penetrates ; (vi) Principle of Ochkam: plurality should not be invoked without necessity ("Pluritas non est ponenda sine necessitate") ; (vii) Goguel's Principle: during the deformation, the volume of the sediment remains more or less constant ; (viii) Principle of the Original Lateral Continuity: the sedimentary layers settle down in lateral continuity ; (ix) Walther's Principle, in conforming strata, vertically succeeding facies occur laterally in adjacent environments ; (x) Dextrological Principle, if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) The principle of Uniformity: geological changes are due mainly to the same ongoing processes and changes that are currently observed ; (xii) Principle of Supoerposition: in a slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers above ; (xiii) Principle of Catastrophism: changes that occurred on Earth were due to the occurrence of major natural disasters ; (xiii) Principle of the Continental Drift: the continental masses have a small density and, for this reason, floated on the dense masses of ocean, moving and changing the surface of the planet ; (xiv) Principle of Plate Tectonics: the continents do note move, but the lithospheric plates that contain them, etc.

(*) Fossils are preserved remains or traces of animals, plants or other living things on rocks, such as body molds or parts thereof, traces and footprints. The totality of the fossils and their placement in the rock formations and sedimentary layers is known as fossil record. The word "fossil" derives from the Latin term "fossilis" meaning "to be unearthed". The science that studies the fossils is Paleontology. Fossilization, rarely, occurs because the organic matter of living things tends to be rapidly decomposed. Therefore, for an organism to be fossilized, the remains must be covered by sediments as soon as possible. There are different types of fossils and different processes of fossilization.

Principle of Intersection.........................................................................................................................Principe d'intersection

Princípio de intersecção / Principio de intersección / Prinzip der Kreuzung / 交集原则 / Принцип пересечения / Principio di intersezione /

The most recent lodes* (dykes) displace the oldest lodes (dykes).

See : « Relative Age »
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« Isochron »
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« Geological Principle »

In this figure, it is t lode A that has displaced the fillet B which is, certainly, more recent (note that the observation surface is more or less flat). This principle, called the intersection principle, can also be used to date fault systems. The faults are younger than all the rocks they move and older than the rocks that fossilize them in an unconformity. It can also be said younger faults shift older faults. However, this principle is valid only when applied to relatively flat observation surfaces. In isochrones structural maps (equal time) or isohypses (contours), due to the topography, is the fault or the apparently displaced lode which is the most recent. In addition to this geological principle there are others of which the most important are: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Original Horizontality: the sedimentary layers deposit horizontally ; (iii) Principle of Intrusion: an igneous intrusive rock is younger than the one it penetrates ; (iv) Principle of the Original Lateral Continuity which states: the sedimentary layers are deposited in lateral continuity ; (v) Principle of Superposition, in a non or slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers successively above ; (vi) Principle of Fossil Succession: the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (vii) Goguel's Principle: during deformation, the volume of the sediments is more or less constant ; (viii) The Walther-facies Principle: succeeding vertically in conforming strata, succeeded laterally in adjacent environments ; (ix) Dextrological Principle: if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (x) Principle of the Carbonated Bucket: the growth of an edged platform is determined by the growth of the edge ; (xi) Principle of Uniformitarianism: geological changes are due to the same processes and continuous changes that are observed today ; (xii) Principle of Ochkam: plurality should not be invoked without necessity, etc.

(*) In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fissure (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock. (https://en.wikipedia.org/wiki/Lode).

Principle of Intrusion............................................................................................................................................Principe de intrusion

Princípio de intrusão / Principio de intrusión / Prinzip der Intrusion / 入侵原理 / Принцип интрузии / Principio di intrusione /

An intrusive rock is younger than the one it penetrates.

Se : « Relative Age »
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« Geological Principle »
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« Truncation »

This principle indicates that the relative age between two igneous rocks or between an igneous rock and a sedimentary rock can be deduced by the geometric relations between them. Indeed, as illustrated on this tentative interpretations of a Canvas auto-trace of Rockwall depression (offshore of England) regional line, it is evident that the volcanic intrusions are posterior to the rocks they cross, even if they are of volcanic origin. Besides this geological principle there are other principles in the geology of which the most important are: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Original Lateral Continuity: the sedimentary layers settle down in lateral continuity, they thin themselves until they disappear or end by downlaps or onlap against the edges of the original depositional sectors ; (iii) Principle of Original Horizontality: the sedimentary layers deposit horizontally ; (iv) Principle of Intersection: the most recent filaments move the oldest filaments ; (v) Principle of Superposition: in a non or slightly deformed sedimentary rocks, the oldest layers are at the base and the most recent layers successively up ; (vi) Principle of Fossil Succession: the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (vii) Goguel's principle, during deformation, the volume of the sediment is, more or less, constant ; (viii) Walther's principle, vertically succeeding facies in the conforming strata follow, laterally, in adjacent environments ; (ix) Dextrological Principle, if a reference system rotates in the clockwise direction an object and deflected (Coriolis effect) to the left in the direction of motion ; (x) Principle of Carbonated Bucket: the growth of an edged platform is determined by the growth of the edge ; (xi) Principle of Uniformitarianism: geological changes are due mainly to the same ongoing processes and changes that are currently observed ; (xii) Principle of Ochkam: plurality should not be invoked without necessity, "Pluritas non est ponenda sine necessita", etc.

Principle of Original Horizontality.......................................Principe d'horizontalité originelle

Princípio da horizontalidade original / Principio de horizontalidad original / Prinzip der ursprünglichen Horizontalität / 原来水平原则 / Принцип исходной горизонтальности / Principio di orizzontalità originaria /

Sedimentary layers deposit horizontally. This principle has been greatly improved. Today, we know stratification plans are chronostratigraphic surfaces composed of geological environments with different slopes. Alluvial deposits (located upstream of the bayline), continental slope deposits and, in particular, the Gilbert deltas do not deposit horizontally. Taking into account the low value of sediment slopes (except for certain carbonates and submarine slope fans), it can be said this principle, in its broad lines, is valid. Most of the sedimentary layers settle with slopes lower than 10°, which is not too far from horizontal.

See: « Deposition (clastics) »
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« Depositional Dip »
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« Geological Principle »

One of the first scientists to oppose the church in defence of geology was the young Danish doctor named Niels Stenson, considered the "father of stratigraphy", but known by the Latinized name Nicolau Steno (1638-1686) who arrived in Florence (Italy) for invitation of the Grand Duke Ferdinando II II (http://ufrr.br/lapa/index.php?option= com_content &view=article&IDML=%2095). The principle of original horizontality, which is still valid today, is one of the three principles of Nicolaus Steno, (born in Copenhagen, Denmark, and lived between 11 January 1638 and 25 November 1686), who was one of the pioneers anatomy and geology and is considered by many geoscientists as one of the fathers of geology and stratigraphy. This principle has been improved recently. We know today that bedding plans are chronostratigraphic surfaces composed of geological environments with different slopes. Alluvial deposits (located upstream of the bayline), continental slope deposits and, in particular, Gilbert-type deltas do not deposit horizontally. In view of the low value of sedimentary slopes (exception made for certain carbonates and submarine slope fans), it may be said this principle, in its broad lines, is valid. The great majority of the sedimentary layers deposit with slopes inferior to 10°, which is not very far from the horizontal. With the advent of seismic reflection, and later with the advent of sequential stratigraphy and especially the seismostratigraphy* all geoscientists find this principle very approximate. In fact, along a chronostratigraphic line, several slope breaks can be, easily, identified, mainly, on regional seismic lines, which from the continent to seaward are: a) Bayline break ; b) Depositional coastal break (roughly the shoreline) ; c) Base of the delta slope break ; d) top of the continental slope break ; and e) Base of the continental slope break. Thus, large-scale deposits, more or less, inclined downhill formed upstream of the bayline (alluvial deposits), in the delta slope and in the continental slope. Besides this principle, in Geology there are many other principles or hypotheses, among which we can mention: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Carbonated Bucket: the architecture of the growth of a fringed carbonate platform resembles the geometry of a bucket or inverted cone trunk ; (iii) Goguel's principle: during the deformation, the volume of the sediment remains more or less constant ; (iv) Principle of Intersection: the most recent dykes move the oldest dykes ; (v) Principle of Intrusion: an igneous intrusive rock is younger than the rock it penetrates ; (vi) Principle of Superposition: in a slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers above ; (vii) Ochkam's Principle: plurality should not be invoked without necessity ; (viii) Principle of the Original Lateral Continuity: the sedimentary layers settle down in lateral continuity ; (ix) Walther's principle: in conforming strata, vertically succeeding facies occur, laterally, in adjacent environments ; (x) Dextrological Principle: if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) Principle of Uniformity: geological changes are due mainly to the same ongoing processes and changes that are currently observed ; (xii) Principle of Fossil Succession: the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (xiii) Principle of Catastrophism: changes that occurred on Earth were due to the occurrence of major natural disasters ; (xiv) Principle of the Drift of the Continents: the continental masses have a small density and, for that reason, they floated on the dense masses of the ocean, moving and changing the surface of the planet ; (xv) Principle of Plate Tectonics: it is not the continents that move, but the lithospheric plates that contain these continents ; (xvi) Principle of Neocatastrophism: which admits Uniformitarianism as the main guide, but does not exclude that occasional catastrophic phenomena have contributed to any changes in the earth's surface; in other words, Neocatastrophism associates catastrophic ideas with Uniformitarianism to explain certain phenomena such as the extinction of dinosaurs, etc.

(*) Discipline of the stratigraphy that interprets the seismic data in a stratigraphic context, taking into account that the seismic reflections are generated by physical surfaces in the rocks, such as bedding planes, groups of beds, downlap surfaces base surfaces and unconformities, characterized by different values of seismic impedance (product of density and velocity). The stratigraphic interpretation of the seismic sections is done through the identification of stratigraphic cycles and, particularly, sequence-cycles. The development of seismostratigraphy provided other disciplines, such as sedimentology, stratigraphy and tectonics, new criteria for the study of sedimentary successions, which allowed the emergence of a modern methodology of study, the sequential stratigraphy.

Principle of Original Lateral Continuity.....................Principe de la continuité latérale originelle

Princípio da continuidade lateral original / Principio de continuidad lateral original / Prinzip der ursprünglichen seitlichen Kontinuität / 原来横向连续性原则 / Принцип исходной горизонтальной выдержанности коллектора / Principio di originaria continuità laterale /

The sedimentary layers settle in lateral continuity. They thin until they disappear or lapout by downlapping or onlapping against the edges of the original deposition areas.

See: « Correlation »
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« Erosion »
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« Geological Principle »

By the end of the eighteenth century, science was still heavily influenced by religion and there was a belief that Earth was young, about 6,000 years old. Not only were the Earth's age estimates influenced by the Bible, but fossils were also interpreted on the basis of the scriptures. In this context, the fossils were recognized as remains of animals that were victimized by the great universal flood, setting themselves up as key witnesses to the flood. It was from the studies of some scientists who were not content with these simplistic explanations about the fossils that this scenario began to change. One of the first scientists to oppose the church in defence of geology was the young Danish doctor named Niels Stenson, considered the "father of stratigraphy", but known by the Latinized name Nicolau Steno (1638-1686) who arrived in Florence, Italy for invitation of the Grand Duke Ferdinando II (http://ufrr.br / laps / index.asp? option = contentment & view = article & id =% 2095). The principle of original lateral continuity, which is still valid today, is one of the three principles of Nicolaus Steno, (born in Copenhagen, Denmark, and lived between 11 January 1638 and 25 November 1686), which was one of the pioneer of anatomy and geology and considered by many geoscientists as one of the fathers of geology and stratigraphy. This principle assumes that the sediment layers are continuous and extend in all directions until their thickness becomes zero. It is based on the following facts: (i) Layer deposition is horizontal and parallel to the deposition surface ; (ii) The strata are bounded by planes defining their lateral continuity ; (iii) A stratum always has the same age along its entire length regardless of the occurrence of lateral changes of lithology ; (iv) A bounded layer a base and a top and defined by a particular facies (lithology and associated fauna) have the same age along its lateral extension. This principle admits that the lateral continuity of the sediments can disappear by erosion or due to tectonic movements. The sediments at the time of deposition are in continuity, but later, for instance, they may be separated due to the formation of river valleys. Such an apparent discontinuity, so well understood today, was very difficult to explain in the seventeenth century. Thus, it is possible to establish correlations between sedimentary columns of distinct areas, even when they are far apart from each other. Besides this principle, in Geology there are many other principles or hypotheses, among which we can mention: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Carbonated Bucket: the architecture of the growth of a fringed carbonated platform resembles the geometry of a bucket or inverted cone trunk, with the mouth wider than the bottom ; (iii) Principle of Original Horizontality: the sedimentary layers deposit horizontally (not totally true) ; (iv) Principle of Intersection: the most recent filaments move the oldest filaments ; (v) Principle of Intrusion, an igneous intrusive rock is younger than the rock it penetrates; (vi) Principle of Superposition: in a slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers above ; (vii) Ochkam's Principle: plurality should not be invoked without necessity: "Pluritas non est ponenda sine necessitate" ; (viii) Goguel's principle: during the deformation, the volume of the sediment remains more or less constant; (ix) Walther's Principle: in conforming strata, vertically succeeding facies occur laterally in adjacent environments ; (x) Dextrological Principle: if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) Principle of Uniformitarianism: geological changes are due mainly to the same processes and continuous changes that are observed today: "The Present is the key of the Past" ; (xii) Principle of Fossil Succession: the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (xiii) Principle of Catastrophism: changes that occurred on Earth were due to the occurrence of major natural disasters; (xiii) Principle of the Continental Drift, the continental masses have a small density and, for this reason, floated on the dense masses of ocean, moving and changing the surface of the planet ; (xiv) Principle of Plate tectonics: it is not the continents that move, but the lithospheric plates that contain these continents ; (xv) Principle of Neocatastrophism: admits Uniformitarianism as the main guide, but does not exclude that occasional catastrophic phenomena have occurred, etc.

Principle of Superposition......................................................................................................Principe de superposition

Princípio da sobreposição / Principio de superposición / Superpositionsprinzip /叠加原理 / Принцип наложения / Principio di sovrapposizione /

In a sedimentary series not, or slightly, deformed, the oldest layers are at the base and the most recent layers, successively, upwards. This principle is still valid today. It has not undergone any modification since Steno (except for the terraces).

See: « Relative Age »
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« Geological Principle »
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« Repetitive Sedimentation »

This principle is one of the three great geological principles advanced by Steno*: "At the moment in any one stratum was deposited, all the matter that rested on it was fluid, therefore, at the moment in which the lower stratum was deposited, neither stratum existed". Steno was one of the first scientists to oppose the church in defense of geology. It was the young Danish doctor named Niels Stenson, considered the" father of stratigraphy ", but known by the Latinized name Nicholas Steno (1638-1686) who arrived in Florence, Italy at the invitation of Grand Duke Ferdinand II (http://ufrr.br/lapa/index.php?option=com_content&view=article&id=%2095). The original superposition principle is one of the three principles of Nicolaus Steno. As illustrated on this tentative geological interpretation of a Canvas auto-trace of Maracaibo Lake (Venezuela) seismic line, the principle of superposition is more than evident in regions not deformed by shortening. When sediments are, greatly, shortened, reverse faults may form and older sedimentary intervals may overlap the more recent intervals, as can be seen in the lower part of the proposed reverse failure in the central part of this tentative interpretation. However, it can be said in regions where the sedimentary shortening is small, the principle of overlap advanced by Nicolas Steno in the 17th century is valid for all sedimentary deposits, with a particular restriction on terraces. In fact, in a succession of terraces (each of which is formed by a flat or slightly inclined surface called a step, bounded on the one hand by a slope with a steeper slope), that they are fluvial, marine, lacustrine or glacial, the most recent terraces are deposited at a lower altitude than the older terraces. Besides this principle, in Geology there are many other principles or hypotheses, among which we can mention: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Carbonated Bucket: the architecture of the growth of a fringed carbonate platform resembles the geometry of a bucket or inverted cone trunk ; (iii) Principle of Original Horizontality: the sedimentary layers deposit horizontally (not totally true) ; (iv) Principle of Intersection: the most recent filaments move the oldest filaments ; (v) Principle of Intrusion: an igneous intrusive rock is younger than the rock it penetrates ; (vi) Ochkam's Principle: plurality should not be invoked without necessity: "Pluritas non est ponenda sine necessitate"; (vii) Goguel's Principle: during the deformation, the volume of the sediment remains more or less constant ; (viii) Principle of the Original Lateral Continuity: the sedimentary layers settle in lateral continuity ; (ix) Walther's Principle: in conforming strata, vertically succeeding facies occur, laterally, in adjacent environments ; (x) Dextrological Principle: if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) Principle of Uniformity: geological changes are due mainly to the same ongoing processes and changes that are currently observed ; (xii) Principle of Fossil Succession, the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence ; (xiii) Principle of Catastrophism: changes that occurred on Earth were due to the occurrence of major natural disasters ; (xiii) Principle of the Continental Drift, the continental masses have a small density and, for this reason, floated on the dense masses of ocean, moving and changing the surface of the planet ; (xiv) Principle of Plate Tectonics: it is not the continents that move, but the lithospheric plates that contain these continents ; (xiv) Principle of Neocatastrophism: admits Uniformitarianism as the main guide, but does not exclude that occasional catastrophic phenomena have have contributed to any changes in the land surface; in other words, Neocatastrophism associates catastrophic ideas with Uniformitarianism to explain certain phenomena such as the extinction of dinosaurs, etc.

(*) In 1669, Niels Stenson (1638-1686), better known then and now by his Latinized name Nicolaus Steno, formulated some basic rules that helped him to understand Tuscan rocks and various objects contained within them. In his preliminary work, "De Solido Intra Solidum Naturaliter Contento - Dissertationis Prodromus", included several propositions that have become fundamental for geoscientists studying all types of rocks, of which three are known as Steno's principles: (i) Principle of Superposition ; (ii) Principle of Original Horizontality and (iii) Principle of Lateral Continuity (https://www.thoughtco.com/stenos-laws-or-principles-1440787).

Principle of Uniformitarism.........................................................................................Principe d'Uniformitarisme

Princípio do Uniformitarismo / Principio de uniformitarismo / Prinzip der Uniformitarismus / 均变原理 / Принцип униформизма / Principio di uniformitarianismo /

Hypothesis according which geological changes on Earth are due, mainly, to processes and continuous changes like those that are observed today.

See: « Depositional Model (sand-shale) »
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« Sequential Stratigraphy »
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« Geological Principle »

The principle of Uniformitarianism, as well as the principle of Catastrophism are hypotheses about the Earth's geological history. The first one says that the main cause of terrestrial changes are slow and continuous processes, such as those that are observed today. On the contrary, Catastrophism says they are a small number of drastic events that are the main cause of the geological changes. Uniformitarianism is, often, proclaimed as "the Present is the key to the Past." Besides these principles, in geology, there are many others: (i) Principle of Composition: a rock represented by fragments in another rock is older than the rock that contains them ; (ii) Principle of the Original Lateral Continuity: the sedimentary layers settle in lateral continuity, they thin until they disappear or end by downlapping or onlapping ; (iii) Principle of the Original Horizontality: the sedimentary layers deposit horizontally, however today we know that the stratification planes are chronostratigraphic surfaces composed of geological environments with different inclinations ; (iv) Principle of Intersection: the most recent filaments move the oldest filaments ; (v) Principle of Intrusion, an igneous intrusive rock is younger than the one it penetrates ; (vi) Principle of Superposition: in a slightly deformed sedimentary series, the oldest layers are at the base and the most recent layers above ; (vii) Ochkam's Principle: plurality should not be invoked without necessity ; (viii) Goguel's Principle: during the deformation, the volume of the sediments remains more or less constant ; (ix) Walther's Principle: in conforming strata, vertically succeeding facies occur laterally in adjacent environments ; (x) Dextrological Principle: if a reference system rotates clockwise the deflection (Coriolis effect) is to the left of the object, in the direction of motion ; (xi) Principle of the Carbonated Bucket: the growth of an edged platform is determined by the growth of the shoreline ; (xii) Principle of Fossil Succession: the distribution of fossils in rocks is not unpredictable, it follows a definite vertical sequence, etc.

Probable Reserves (HC)................................................................................................................................................Réserves probables (HC)

Reservas prováveis / Reservas probables (HC) / Wahrscheinlichen Reserven (HC) / 可能储量（慧聪） / Вероятные запасы (УВ) / Riserve probabili (HC) /

Part of unproved reserves (P₂), whose analysis of geological data and engineering suggests they are less likely to be commercially produced under future economic conditions or technological developments than proved reserves. Probable reserves are less certain than proven reserves. The designation of probable means that the confidence level to recover the most probable proved reserves (P₁+P₂) is at least 50%

See: « Reserves »
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« Possible Reserves (HC) »
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« Proven Reserves (HC) »

The probable reserves are the quantified estimates of hydrocarbons (crude oil, natural bitumen, natural gas, natural gas liquids) in addition to proven reserves, which from a certain date, the geological and engineering analysis of a certain data numbers suggested a probability of existence and, possibly, are not commercially recoverable under present economic or technological conditions. Probable reserves are less certain than proven reserves. In this context, it is reasonable to expect that the probability of recovery of the amount estimated as probable and proven reserves ranges between 40 and 60%. In this graph, probable reserves determined on the basis of geological maps or seismic maps of the or reservoir-rocks represent about 140 million barrels (140 Mb) for a 50% confidence level. The set of proved reserves (P₁) plus probable reserves (P₂) is 350 Mb. J. Laherrere (1999) says that when one speaks of reserves, one can not forget that: (i) They are the total of future production (expected) ; (ii) They are uncertain until the last day of production ; (iii) They are confidential ; (iv) There is a conflict between the method of calculation deterministic (1 value) and probabilistic (3 values) ; (v) Probabilities are subjective and poorly understood ; (vi) Only the expected values can be added ; (vii) Only fashion values can be multiplied ; (viii) There is no consensus in the definitions, since the publication of reserves is a political act and depends on the image that the company announcing it wants to give ; (ix) There are internal reserves (geoscientist, engineer, economist, etc.) and external reserves (for bankers, taxes, stockholders, etc.) ; (x) There are initial reserves and reserves remaining at a certain date ; (xi) Undeveloped reserves should be considered as initial (which a large part of small oil companies forget).