Chert is a fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline silica. Depending on its origin, it can contain either microfossils, small macrofossils, Chert occurs as oval to irregular nodules in greensand, limestone and dolostone formations as a replacement mineral, where it is formed as a result of some type of diagenesis. Where it occurs in chalk or marl, it is usually called flint and it occurs in thin beds, when it is a primary deposit. Thick beds of chert occur in marine deposits. These thickly bedded cherts include the novaculite of the Ouachita Mountains of Arkansas, the banded iron formations of Precambrian age are composed of alternating layers of chert and iron oxides. Chert occurs in deposits and is known as diatomaceous chert. Diatomaceous chert consists of beds and lenses of diatomite which were converted during diagenesis into dense, in petrology the term chert is used to refer generally to all rocks composed primarily of microcrystalline, cryptocrystalline and microfibrous quartz.
The term does not include quartzite, chalcedony is a microfibrous variety of quartz. Strictly speaking, the flint is reserved for varieties of chert which occur in chalk. Among non-geologists, the distinction between flint and chert is often one of quality - chert being lower quality than flint, among petrologists, chalcedony is sometimes considered separately from chert due to its fibrous structure. Since many cherts contain both microcrystalline and microfibrous quartz, it is difficult to classify a rock as completely chalcedony. The cryptocrystalline nature of chert, combined with its above average ability to resist weathering, recrystallization, for example, The 3.2 Ga chert of the Fig Tree Formation in the Barbeton Mountains between Swaziland and South Africa preserved non-colonial unicellular bacteria-like fossils. The Gunflint Chert of western Ontario preserves not only bacteria and cyanobacteria but believed to be ammonia-consuming and some that resemble green algae. The Apex Chert of the Pilbara craton, Australia preserved eleven taxa of prokaryotes, the Bitter Springs Formation of the Amadeus Basin, Central Australia, preserves 850 Ma cyanobacteria and algae.
The Rhynie chert of Scotland has remains of a Devonian land flora, in prehistoric times, chert was often used as a raw material for the construction of stone tools. Like obsidian, as well as some rhyolites, felsites and this results in conchoidal fractures, a characteristic of all minerals with no cleavage planes. When a chert stone is struck against an iron-bearing surface sparks result and this makes chert an excellent tool for starting fires, and both flint and common chert were used in various types of fire-starting tools, such as tinderboxes, throughout history. Cherts are subject to problems when used as concrete aggregates, deeply weathered chert develops surface pop-outs when used in concrete that undergoes freezing and thawing because of the high porosity of weathered chert
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can release instantaneously when the rate is too great.
The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
It does not include changes from weathering. It is any chemical, physical, or biological change undergone by a sediment after its initial deposition and this process excludes surface alteration and metamorphism. These changes happen at low temperatures and pressures and result in changes to the rocks original mineralogy. There is no boundary between diagenesis and metamorphism, but the latter occurs at higher temperatures and pressures than the former. Hydrothermal solutions, meteoric groundwater, permeability, after deposition, sediments are compacted as they are buried beneath successive layers of sediment and cemented by minerals that precipitate from solution. Grains of sediment, rock fragments and fossils can be replaced by other minerals during diagenesis, porosity usually decreases during diagenesis, except in rare cases such as dissolution of minerals and dolomitization. The study of diagenesis in rocks is used to understand the history they have undergone. From a commercial standpoint, such aid in assessing the likelihood of finding various economically viable mineral.
The process of diagenesis is important in the decomposition of bone tissue, the term diagenesis, literally meaning across generation, is extensively used in geology. However, this term has filtered into the field of anthropology and paleontology to describe the changes, the composite nature of bone, comprising one-third organic and two thirds mineral renders its diagenesis more complex. Three general pathways of the diagenesis of bone have been identified, chemical deterioration of the mineral phase. They are as follows, The dissolution of collagen depends on time, temperature, at high temperatures, the rate of collagen loss will be accelerated and extreme pH can cause collagen swelling and accelerated hydrolysis. The hydrolytic activity plays a key role in the phase transformations that exposes the collagen to accelerated chemical-. Once an individual has been interred, microbial attack, the most common mechanism of bone deterioration, during this phase, most bone collagen is lost and porosity is increased.
The dissolution of the mineral phase caused by low pH permits access to the collagen by extracellular microbial enzymes thus microbial attack, when animal or plant matter is buried during sedimentation, the constituent organic molecules break down due to the increase in temperature and pressure. This transformation occurs in the first few hundred meters of burial and it is generally accepted that hydrocarbons are formed by the thermal alteration of these kerogens. In this way, given certain conditions kerogens will break down to form hydrocarbons through a process known as cracking. These models have been studied and applied in real geological applications
In geology a bed is the smallest division of a geologic formation or stratigraphic rock series marked by well-defined divisional planes separating it from layers above and below. A bed is the smallest lithostratigraphic unit, usually ranging in thickness from a centimetre to several metres and distinguishable from beds above, beds can be differentiated in various ways, including rock or mineral type and particle size. The term is applied to sedimentary strata, but may be used for volcanic flows or ash layers. In a quarry, a bedding is a used for a structure occurring in granite. Three kinds of beds are, parallel beds, cross beds, geological unit Lamination Stratigraphy Stratum Lamina, Laminaset and Bedset
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock is subjected to heat and pressure, causing profound physical and/or chemical change, the protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock. Metamorphic rocks make up a part of the Earths crust. They are classified by texture and by chemical and mineral assemblage and they may be formed simply by being deep beneath the Earths surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure and they are formed when rock is heated up by the intrusion of hot molten rock called magma from the Earths interior. The study of rocks provides information about the temperatures and pressures that occur at great depths within the Earths crust. Some examples of rocks are gneiss, marble, schist.
Metamorphic minerals are those that only at the high temperatures and pressures associated with the process of metamorphism. These minerals, known as index minerals, include sillimanite, staurolite and some garnet. Other minerals, such as olivines, amphiboles, micas and quartz, may be found in metamorphic rocks and these minerals formed during the crystallization of igneous rocks. They are stable at temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are only within certain limits. The change in the size of the rock during the process of metamorphism is called recrystallization. Both high temperatures and pressures contribute to recrystallization, high temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their point of contact. The layering within metamorphic rocks is called foliation, and it occurs when a rock is being shortened along one axis during recrystallization.
This causes the platy or elongated crystals of minerals, such as mica and chlorite and this results in a banded, or foliated rock, with the bands showing the colors of the minerals that formed them. Textures are separated into foliated and non-foliated categories, foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage. For example, slate is a metamorphic rock, originating from shale
Liesegang rings are a phenomenon seen in many, if not most, chemical systems undergoing a precipitation reaction, under certain conditions of concentration and in the absence of convection. The phenomenon was first noticed in 1855 by the German chemist Friedlieb Ferdinand Runge and he observed them in the course of experiments on the precipitation of reagents in blotting paper. In 1896 the German chemist Raphael E. Liesegang, noted the phenomenon when he dropped a solution of silver nitrate on to a layer of gel containing potassium dichromate. After a few hours, sharp concentric rings of silver dichromate formed. It has aroused the curiosity of chemists for many years, when formed in a test tube by diffusing one component from the top, layers or bands of precipitate form, rather than rings. The reactions are most usually carried out in test-tubes into which a gel is formed that contains a dilute solution of one of the reactants and it will encounter the potassium dichromate and will form a continuous region of precipitate at the top of the tube.
After some hours, the region of precipitation is followed by a clear region with no sensible precipitate. This process continues down the tube forming several, perhaps a couple of dozen regions of clearing, over the decades huge number of precipitation reactions have been used to study the phenomenon, and it seems quite general. The gels used are usually gelatin, agar or silicic acid gel, the concentration ranges over which the rings form in a given gel for a precipitating system can usually be found for any system by a little systematic empirical experimentation in a few hours. Often the concentration of the component in the gel should be substantially less concentrated than the one placed on top of the gel. The first feature usually noted is that the bands which form farther away from the interface are generally farther apart. Some investigators measure this distance and report in some systems, at least, the most frequent observation is that the distance apart that the rings form is proportional to the distance from the liquid-gel interface.
This is by no means universal and sometimes they form at essentially random, another feature often noted is that the bands themselves do not move with time, but rather form in place and stay there. For very many systems the precipitate that forms is not the fine coagulant or flocs seen on mixing the two solutions in the absence of the gel, but rather coarse, crystalline dispersions. Sometimes the crystals are separated from one another, and only a few form in each band. The precipitate that forms a band is not always a binary insoluble compound and it is not possible to make any general statement of the effect of the composition of the gel. A system that forms nicely for one set of components, might fail altogether and require a different set of conditions if the gel is switched, the essential feature of the gel required is that thermal convection in the tube be prevented altogether. Most systems will form rings in the absence of the system if the experiment is carried out in a capillary
Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. The new pore-filling minerals form bridges between original sediment grains, thereby binding them together, in this way sand becomes sandstone, and gravel becomes conglomerate or breccia. Cementation occurs as part of the diagenesis or lithification of sediments, cementation occurs primarily below the water table regardless of sedimentary grain sizes present. Large volumes of water must pass through sediment pores for new mineral cements to crystallize. Common mineral cements include calcite, quartz or silica phases like cristobalite, iron oxides, and clay minerals, cementation is continuous in the groundwater zone, so much so that the term zone of cementation is sometimes used interchangeably. Cementation occurs in fissures or other openings of existing rocks and is a process more or less in equilibrium with a dissolution or dissolving process. Cement found on the sea floor is commonly aragonite and can take different textural forms and these textural forms include pendant cement, meniscus cement, isopachous cement, needle cement, botryoidal cement, blocky cement, syntaxial rim cement, and coarse mosaic cement.
The environment in each of the cements is found depends on the pore space available. Cements that are found in phreatic zones include, blocky, as for calcite cementation, which occurs in meteoric realms, the cement is produced by the dissolution of less stable aragonite and high-Mg calcite. Classifying rocks while using the Folk classification depends on the matrix, beachrock is a type of carbonate beach sand that has been cemented together by a process called synsedimentary cementation. Beachrock may contain meniscus cements or pendant cements, as the water between the narrow spaces of grains drains from the beachrock, a small portion of it is held back by capillary forces, where meniscus cement will form. Pendant cements form on the bottom of grains where water droplets are held, hardgrounds are hard crusts of carbonate material that form on the bottom of the ocean floor, below the lowest tide level. Isopachous cement forms in subaqueous conditions where the grains are surrounded by water.
Carbonate cements can be formed by organisms such as Sporosarcina pasteurii, which binds sand together given organic compounds. Boggs, Sam Jr.2006, Principles of Sedimentology and Stratigraphy, Sam, Jr.2011, Principles of Sedimentology and Stratigraphy, 5th ed. Chiung-Wen Chou, Eric Seagren, Ahmet Aydilek, Timothy Maugel, bacterially-Induced Calcite Precipitation via Ureolysis, American Society for Microbiology 11 November 2008 Retrieved 20 February 2010
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology.
Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geochemistry, sedimentary rocks have been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, rock fragments, clay minerals, and mica, any type of mineral may be present, clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions, gravel and mud and this tripartite subdivision is mirrored by the broad categories of rudites and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name.
Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks, all other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Clean sandstones with open space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes, six sandstone names are possible using the descriptors for grain composition and the amount of matrix. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides, common rust is a form of iron oxide. Iron oxides are used as inexpensive, durable pigments in paints, coatings. Colors commonly available are in the end of the yellow/orange/red/brown/black range. When used as a coloring, it has E number E172. Limonite Iron oxide nanoparticles List of inorganic pigments Information from Nano-Oxides, http, //chemed. chem. purdue. edu/demos/demosheets/12.3. html http, //minerals. usgs. gov/minerals/pubs/commodity/iron_oxide/ CDC - NIOSH Pocket Guide to Chemical Hazards de
Shawnee National Forest
The Shawnee National Forest is a United States National Forest located in the Ozark and Shawnee Hills of Southern Illinois, United States. Forest Service, it consists of approximately 280,000 acres of federally managed lands, in descending order of land area it is located in parts of Pope, Union, Alexander, Gallatin and Massac counties. Forest headquarters are located in Harrisburg, there are local ranger district offices in Jonesboro and Vienna. The Shawnee National Forest is the single largest publicly owned body of land in the state of Illinois, designated as the Illini and Shawnee Purchase Units, President Franklin D. Roosevelt declared these purchase units to be the Shawnee National Forest in September 1939. Most of the added to the Forest in its first decade of existence was exhausted farmland. Throughout the 1930s and 1940s, the Civilian Conservation Corps planted pine trees to prevent erosion, the Forest is home to many hardwood trees and other plant and animal species characteristic of the region.
To mainstream organizations such as the Sierra Club and the Green Party, the wise use movement once played an active role in lobbying for its vision of the Shawnee National Forest. Today a more cooperative atmosphere has developed, although some controversy remains with a few, in 2006, the Forest Service completed the development of a new Forest Management Plan for the Shawnee National Forest. This plan, adopted every 10–15 years, outlines the policies and practices of the U. S. Forest Service in overseeing the management of the Shawnee National Forest. The 2006 Forest Plan was completed in collaboration with many environmental and public groups and is designed to maintain, during the Illinoian Stage, the Laurentide ice sheet covered up to 85 percent of Illinois. The southern margin of this ice sheet was located within what is now the area of the Shawnee National Forest, there are many points of interest marking the southern edge of the glacier. Some are located within the Forest boundary, others are on land in proximity.
Little Grand Canyon is located within the Shawnee National Forest and this is accessible off Illinois Route 127 south of Murphysboro, Illinois. A small creek with a watershed has carved an impressive rock canyon, more than 200 feet deep. The southern edge of the ice sheet was just to the north of Little Grand Canyon, blocks of ice slid off the face of the glacier, carried by enormous volumes of meltwater, to carve this tiny canyon. In the deep shade of the canyon are relict species of Arctic plants left over from its ancient origin, Cedar Lake is an artificial lake formed by damming Cedar Creek. The lake is accessible off Illinois Route 127, south of Murphysboro, in this area, the Illinoian Glacier climbed the Shawnee Hills at its southern margin. The glacier blocked the waterways flowing north down the hills and this drainage formed a creek running northwest along the face of the glacier
Friedrich Wilhelm Ostwald was a German chemist. He received the Nobel Prize in Chemistry in 1909 for his work on catalysis, chemical equilibria, Jacobus Henricus van t Hoff, and Svante Arrhenius are usually credited with being the modern founders of the field of physical chemistry. Ostwald was born ethnically Baltic German in Riga, to master-cooper Gottfried Wilhelm Ostwald and he was the middle child of three, born after Eugen and before Gottfried. The date 1908 is often given for the invention of the Ostwald process, six years might simply have been the bureaucratic interval between filing the patent and the time it was granted. Ostwald did significant work on dilution theory leading to his discovery of the law of dilution which is named after him, Ostwalds rule concerns the behaviour of polymorphs. The word mole, according to Gorin, was introduced into chemistry around 1900 by Ostwald, Ostwald defined one mole as the molecular weight of a substance in mass grams. The concept was linked to the gas, according to Ostwald.
Ironically, Ostwalds development of the concept was directly related to his philosophical opposition to the atomic theory. He explained in a conversation with Arnold Sommerfeld that he was converted by Jean Perrins experiments on Brownian Motion, in 1906 Ostwald was elected a member of the International Committee on Atomic Weights. As a consequence of World War I this membership ended in 1917 and was not resumed after the war, the 1917 Annual report of the committee ended with the unusual note, Because of the European war the Committee has had much difficulty in the way of correspondence. The German member, Professor Ostwald, has not been heard from in connection with this report, possibly the censorship of letters, either in Germany or en route, has led to a miscarriage. In addition to his work in chemistry, Wilhelm Ostwald was very productive in a broad range of fields. His published work, which includes numerous philosophical writings, contains about forty thousand pages, Ostwald was engaged in the peace movement of Berta von Suttner.
Among his other interests, Ostwald was an amateur painter who made his own pigments. He wrote several publications in the field, such as his Malerbriefe and his work in color theory was influenced by that of Albert Henry Munsell, and in turn influenced Paul Klee and members of De Stijl, including Piet Mondrian. Ostwald donated half the proceedings of his 1909 Nobel prize to the Ido movement, Ostwald adopted the philosophy of Monism as advanced by Ernst Haeckel and became President of the Monistic Alliance in 1911. He used the Alliances forum to promote Social Darwinism, Ostwalds Monism influenced Carl G. Jungs identification of psychological types. He was one of the directors of the Die Brücke institute in Munich, the institute was sponsored, from Ostwalds Nobel Prize money
Stratigraphy is a branch of geology which studies rock layers and layering. It is primarily used in the study of sedimentary and layered volcanic rocks, stratigraphy has two related subfields, lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy. The first practical application of stratigraphy was by William Smith in the 1790s. Another influential application of stratigraphy in the early 19th century was a study by Georges Cuvier, variation in rock units, most obviously displayed as visible layering, is due to physical contrasts in rock type. This variation can occur vertically as layering, or laterally, and these variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit. Key concepts in stratigraphy involve understanding how certain geometric relationships between rock layers arise and what these geometries imply about their original depositional environment. The basic concept in stratigraphy, called the law of superposition, states, in a stratigraphic sequence.
Chemostratigraphy studies the changes in the proportions of trace elements and isotopes within. Carbon and oxygen isotope ratios vary with time, and researchers can use those to map subtle changes that occurred in the paleoenvironment and this has led to the specialized field of isotopic stratigraphy. Biostratigraphy or paleontologic stratigraphy is based on evidence in the rock layers. Strata from widespread locations containing the fossil fauna and flora are said to be correlatable in time. Biologic stratigraphy was based on William Smiths principle of succession, which predated. It provides strong evidence for the formation and extinction of species, the geologic time scale was developed during the 19th century, based on the evidence of biologic stratigraphy and faunal succession. One important development is the Vail curve, which attempts to define a global historical sea-level curve according to inferences from worldwide stratigraphic patterns, stratigraphy is commonly used to delineate the nature and extent of hydrocarbon-bearing reservoir rocks and traps of petroleum geology.
Chronostratigraphy is the branch of stratigraphy that places an absolute age, a gap or missing strata in the geological record of an area is called a stratigraphic hiatus. This may be the result of a halt in the deposition of sediment, the gap may be due to removal by erosion, in which case it may be called a stratigraphic vacuity. It is called a hiatus because deposition was on hold for a period of time, a physical gap may represent both a period of non-deposition and a period of erosion. A geologic fault may cause the appearance of a hiatus, magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences