1.
Sorting (sediment)
–
Sorting describes the distribution of grain size of sediments, either in unconsolidated deposits or in sedimentary rocks. This should not be confused with crystallite size, which refers to the size of a crystal in a solid. Crystallite is the block of a grain. Very poorly sorted indicates that the sediment sizes are mixed, whereas well sorted indicates that the sediment sizes are similar, in the field, sedimentologists use graphical charts to accurately describe the sorting of a sediment using one of these words. The degree of sorting may also indicate the energy, rate, and/or duration of deposition, sorting of sediments can also be affected by reworking of the material after deposition, for instance, by winnowing. Well sorted rocks are generally porous, while poorly sorted rocks have low porosity, grain size Graded bedding Rounding Porosity Soil texture Sediment transport
2.
Glacier
–
A glacier is a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs and they also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice, between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earths land surface, continental glaciers cover nearly 13,000,000 km2 or about 98 percent of Antarcticas 13,200,000 km2, with an average thickness of 2,100 m. Greenland and Patagonia also have huge expanses of continental glaciers, Glacial ice is the largest reservoir of fresh water on Earth. Within high altitude and Antarctic environments, the temperature difference is often not sufficient to release meltwater. A large piece of compressed ice, or a glacier, appears blue as large quantities of water appear blue and this is because water molecules absorb other colors more efficiently than blue. The other reason for the color of glaciers is the lack of air bubbles. Air bubbles, which give a color to ice, are squeezed out by pressure increasing the density of the created ice. The word Glaceon is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, the processes and features caused by or related to glaciers are referred to as glacial. The process of establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology, Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, and behavior, cirque glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, a large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have a less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called ice sheets or continental glaciers, several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces, the only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of water, enough that if both melted, global sea levels would rise by over 70 m
3.
Erosion
–
In earth science, erosion is the action of surface processes that remove soil, rock, or dissolved material from one location on the Earths crust, then transport it away to another location. Eroded sediment or solutes may be transported just a few millimetres, the rates at which such processes act control how fast a surface is eroded. Feedbacks are also possible between rates of erosion and the amount of eroded material that is carried by, for example. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, while erosion is a natural process, human activities have increased by 10-40 times the rate at which erosion is occurring globally. At well-known agriculture sites such as the Appalachian Mountains, intensive farming practices have caused erosion up to 100x the speed of the rate of erosion in the region. Excessive erosion causes both on-site and off-site problems, on-site impacts include decreases in agricultural productivity and ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of bodies, as well as sediment-related damage to roads. Intensive agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion, however, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall, and the surface runoff which may result from rainfall, produces four types of soil erosion, splash erosion, sheet erosion, rill erosion. Splash erosion is generally seen as the first and least severe stage in the erosion process. In splash erosion, the impact of a falling raindrop creates a crater in the soil. The distance these soil particles travel can be as much as 0.6 m vertically and 1.5 m horizontally on level ground. If the soil is saturated, or if the rate is greater than the rate at which water can infiltrate into the soil. If the runoff has sufficient flow energy, it will transport loosened soil particles down the slope, sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes, generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are typically of the order of a few centimetres or less and this means that rills exhibit hydraulic physics very different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when water accumulates and rapidly flows in narrow channels during or immediately after heavy rains or melting snow
4.
Glacial motion
–
Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes, most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast or slow, but is typically around 1 metre/day, glacier motion occurs from four processes, all driven by gravity, basal sliding, glacial quakes generating fractional movements of large sections of ice, bed deformation, and internal deformation. In the case of basal sliding, the glacier slides over its bed. This type of motion is enhanced if the bed is soft sediment, if the bed is thawed. Bed deformation is thus limited to areas of sliding. Seasonal melt ponding and penetrating under glaciers shows seasonal acceleration and deceleration of ice flows affecting whole icesheets. There has been a pattern of these ice quakes - Quakes ranged from six to 15 per year from 1993 to 2002, then jumped to 20 in 2003,23 in 2004. A glacier that is frozen up to its bed does not experience basal sliding, internal deformation occurs when the weight of the ice causes the deformation of ice crystals. This takes place most readily near the bed, where pressures are highest. There are glaciers that primarily move via sliding, glacial quakes, if a glaciers terminus moves forward faster than it melts, the net result is advance. Glacier retreat occurs when more material ablates from the terminus than is replenished by flow into that region, glaciologists consider that trends in mass balance for glaciers are more fundamental than the advance or retreat of the termini of individual glaciers. In the years since 1960, there has been a decline in the overall volume of glaciers worldwide. This decline is correlated with global warming, as a glacier thins, due to the loss of mass it will slow down and crevassing will decrease. During the Pleistocene, huge sheets of ice called continental glaciers advanced over much of the earth, the movement of these continental glaciers created many now-familiar glacial landforms. Later, when the glaciers retreated leaving behind their freight of crushed rock and sand, depositional landforms were created, such as moraines, eskers, drumlins, and kames. The stone walls found in New England contain many glacial erratics, at some point, if an Alpine glacier becomes too thin it will stop moving. This will result in the end of any basal erosion, the stream issuing from the glacier will then become clearer as glacial flour diminishes
5.
Deposition (geology)
–
Deposition is the geological process in which sediments, soil and rocks are added to a landform or land mass. Deposition can also refer to the buildup of sediment from organically derived matter or chemical processes, for example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which has induced chemical processes to deposit further calcium carbonate. Similarly, the formation of coal begins with deposition of material, mainly from plants. The null-point hypothesis explains how sediment is deposited throughout a shore profile according to its grain size and this is due to the influence of hydraulic energy, resulting in a seaward-fining of sediment particle size, or where fluid forcing equals gravity for each grain size. The concept can also be explained as sediment of a particular size may move across the profile to a position where it is in equilibrium with the wave, figure 1 illustrates this relationship between sediment grain size and the depth of the marine environment. The relatively strong onshore stroke of the forms a eddy or vortex on the lee side of the ripple, provided the onshore flow persists. Where there is symmetry in ripple shape the vortex is neutralised and this creates a cloudy water column which travels under tidal influence as the wave orbital motion is in equilibrium. R is the radius of the object, ρ is the mass density of the fluid, g is the gravitational acceleration, Cd is the drag coefficient. When the fluid becomes more viscous due to grain sizes or larger settling velocities, prediction is less straight forward. Cohesion of sediment occurs with the grain sizes associated with silts and clays. Akaroa Harbour is located on Banks Peninsula, Canterbury, New Zealand and this research shows conclusive evidence for the null point theory existing on tidal flats with differing hydrodynamic energy levels and also on flats that are both erosional and accretional. Kirby R. Cheniers can be found at any level on the foreshore and this is because sediment grain size analysis throughout a profile allows inference into the erosion or accretion rates possible if shore dynamics are modified. Planners and managers should also be aware that the environment is dynamic. Cementation Cross-bedding Drift Flocculation Longshore drift Overbank Sedimentary rock Sedimentary structures Settling Shields parameter Stokes law Superficial deposits
6.
Terminal moraine
–
A terminal moraine, also called end moraine, is a type of moraine that forms at the snout of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, because the glacier acts very much like a conveyor belt, the longer it stays in one place, the greater the amount of material that will be deposited. The moraine is left as the point of the terminal extent of the ice. Terminal moraines are one of the most prominent types of moraines in the Arctic, one famous terminal moraine is the Giants Wall in Norway which, according to legend, was built by giants to keep intruders out of their realm. In North America, the Outer Lands is a given to the terminal moraine archipelago of the northeastern region of the United States. Other prominent examples of terminal moraines are the Tinley Moraine and the Valparaiso Moraine and these moraines are most clearly seen southwest of Chicago. In Europe, virtually all the terrain in the central Netherlands is made up of a terminal moraine. In New Zealand the Franz Josef Glacier on the West Coast has created the terminal called the Waiho Loop. Glacial landform Postglacial rebound Push moraine Outwash plain Trafalgar Moraine Oak Ridges Moraine List of glacial moraines
7.
Moraine
–
A moraine is any glacially formed accumulation of unconsolidated glacial debris that occurs in both currently and formerly glaciated regions on Earth, through geomorphological processes. Moraines are formed from debris previously carried along by a glacier, lateral moraines are formed at the side of the ice flow and terminal moraines at the foot, marking the maximum advance of the glacier. Other types of moraine include ground moraines, till-covered areas with irregular topography, moraines may be composed of debris ranging in size from silt-sized glacial flour to large boulders. The debris is typically sub-angular to rounded in shape, moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may form through a number of processes, depending on the characteristics of sediment, the dynamics on the ice, moraine forming processes may be loosely divided into passive and active. Passive processes involve the placing of chaotic supraglacial sediments onto the landscape with limited reworking and these moraines are composed of supraglacial sediments from the ice surface. Active processes form or rework moraine sediment directly by the movement of ice and these form push moraines and thrust-block moraines, which are often composed of till and reworked proglacial sediment. Moraine may also form by the accumulation of sand and gravel deposits from glacial streams emanating from the ice margin and these fan deposits may coalesce to form a long moraine bank marking the ice margin. Several processes may combine to form and rework a single moraine, moraines can be classified either by origin, location with respect to a glacier or former glacier, or by shape. Some moraine types are only from ancient glaciers, while medial moraines of valley glaciers are poorly preserved. Lateral moraines are parallel ridges of debris deposited along the sides of a glacier, the unconsolidated debris can be deposited on top of the glacier by frost shattering of the valley walls and/or from tributary streams flowing into the valley. The till is carried along the glacial margin until the glacier melts, lateral moraines stand high because they protect the ice under them from the elements, causing it to melt or sublime less than the uncovered parts of the glacier. Multiple lateral moraines may develop as the glacier advances and retreats, ground moraines are till-covered areas with irregular topography and no ridges, often forming gently rolling hills or plains. They are accumulated at the base of the ice as lodgment till, in alpine glaciers, ground moraines are often found between the two lateral moraines. Ground moraines may be modified into drumlins by the overriding ice, Rogen moraines or ribbed moraines are a type of basal moraines that form a series of ribs perpendicular to the ice flow in an ice sheet. The depressions between the ribs are sometimes filled with water, making the Rogen moraines look like tigerstripes on aerial photographs, Rogen moraines are named after Lake Rogen in Härjedalen, Sweden, the landform’s type locality. End moraines, or terminal moraines, are ridges of unconsolidated debris deposited at the snout or end of the glacier and they usually reflect the shape of the glaciers terminus. Glaciers act much like a belt, carrying debris from the top of the glacier to the bottom where it deposits it in end moraines
8.
Fluvial
–
Fluvial is a term used in geography and geology to refer to the processes associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, fluvial processes include the motion of sediment and erosion or deposition on the river bed. Erosion by moving water can happen in two ways, firstly, the movement of water across the bed exerts a shear stress directly onto the bed. However, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed, at the same time the fragments themselves are ground down, becoming smaller and more rounded. Sediment in rivers is transported as either bedload or suspended load, there is also a component carried as dissolved material. For each grain size there is a velocity at which the grains start to move. However the grains will continue to be transported even if the velocity falls below the entrainment velocity due to the friction between the grains and the river bed. Eventually the velocity will fall low enough for the grains to be deposited and this is shown by the Hjulstrøm curve. A river is continually picking up and dropping solid particles of rock, where the river flow is fast, more particles are picked up than dropped. Where the river flow is slow, more particles are dropped than picked up, areas where more particles are dropped are called alluvial or flood plains, and the dropped particles are called alluvium. Even small streams make alluvial deposits, but it is in the plains and deltas of large rivers that large. The amount of matter carried by a river is enormous. The names of rivers derive from the color that the transported matter gives the water. For example, the Huang He in China is literally translated Yellow River, and it has been estimated that the Mississippi River annually carries 406 million tons of sediment to the sea, the Yellow River 796 million tons, and the Po River in Italy 67 million tons. Lacustrine - of or relating to a lake maritime - of or relating the sea oceanic - of or relating to an ocean palustrine - of or relating to a marsh
9.
Sediment
–
For sediment in beverages, see dregs. For example, sand and silt can be carried in suspension in water and on reaching the sea be deposited by sedimentation. Sediments are most often transported by water, but also wind, beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of transport and deposition. Glacial moraine deposits and till are ice-transported sediments, sediment can be classified based on its grain size and/or its composition. Sediment size is measured on a log base 2 scale, called the Phi scale, composition of sediment can be measured in terms of, parent rock lithology mineral composition chemical make-up. This leads to an ambiguity in which clay can be used as both a size-range and a composition, sediment is transported based on the strength of the flow that carries it and its own size, volume, density, and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow and these relationships are shown in the following table for the Rouse number, which is a ratio of sediment fall velocity to upwards velocity. If the upwards velocity is less than the settling velocity, but still high enough for the sediment to move, it will move along the bed as bed load by rolling, sliding. If the upwards velocity is higher than the velocity, the sediment will be transported high in the flow as wash load. As there are generally a range of different particle sizes in the flow, sediment motion can create self-organized structures such as ripples, dunes, antidunes on the river or stream bed. These bedforms are often preserved in rocks and can be used to estimate the direction. Overland flow can erode soil particles and transport them downslope, the erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion, if overland flow is directly responsible for sediment entrainment but does not form gullies, it is called sheet erosion. If the flow and the substrate permit channelization, gullies may form, glaciers carry a wide range of sediment sizes, and deposit it in moraines. The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation and this expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This can be localized, and simply due to obstacles, examples are scour holes behind boulders, where flow accelerates
10.
Clay
–
Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
11.
Sand
–
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt, Sand can also refer to a textural class of soil or soil type, i. e. a soil containing more than 85% sand-sized particles by mass. The second most common type of sand is calcium carbonate, for example aragonite, for example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Sand is a non renewable resource over human timescales, and sand suitable for making concrete is in high demand, in terms of particle size as used by geologists, sand particles range in diameter from 0.0625 mm to 2 mm. An individual particle in this size is termed a sand grain. Sand grains are between gravel and silt, a 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A1938 specification of the United States Department of Agriculture was 0.05 mm. Sand feels gritty when rubbed between the fingers. ISO14688 grades sands as fine, medium and coarse with ranges 0.063 mm to 0.2 mm to 0.63 mm to 2.0 mm. In the United States, sand is commonly divided into five sub-categories based on size, very fine sand, fine sand, medium sand, coarse sand, and very coarse sand. These sizes are based on the Krumbein phi scale, where size in Φ = -log2D, on this scale, for sand the value of Φ varies from −1 to +4, with the divisions between sub-categories at whole numbers. The composition of sand is highly variable, depending on the local rock sources. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, arkose is a sand or sandstone with considerable feldspar content, derived from weathering and erosion of a granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite or gypsum, Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts and obsidian. Chlorite-glauconite bearing sands are typically green in color, as are sands derived from basaltic with a high olivine content, many sands, especially those found extensively in Southern Europe, have iron impurities within the quartz crystals of the sand, giving a deep yellow color. Sand deposits in some areas contain garnets and other resistant minerals, the study of individual grains can reveal much historical information as to the origin and kind of transport of the grain. Quartz sand that is weathered from granite or gneiss quartz crystals will be angular. It is called grus in geology or sharp sand in the trade where it is preferred for concrete. Sand that is transported long distances by water or wind will be rounded, people who collect sand as a hobby are known as arenophiles
12.
Gravel
–
Gravel /ˈɡrævəl/ is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel is categorized by the Udden-Wentworth scale into granular gravel and pebble gravel, one cubic metre of gravel typically weighs about 1,800 kg. Gravel is an important commercial product, with a number of applications, many roadways are surfaced with gravel, especially in rural areas where there is little traffic. Globally, far more roads are surfaced with gravel than with concrete or tarmac, both sand and small gravel are also important for the manufacture of concrete. Large gravel deposits are a geological feature, being formed as a result of the weathering. The action of rivers and waves tends to pile up gravel in large accumulations and this can sometimes result in gravel becoming compacted and concreted into the sedimentary rock called conglomerate. Where natural gravel deposits are insufficient for human purposes, gravel is often produced by quarrying and crushing hard-wearing rocks, such as sandstone, limestone, quarries where gravel is extracted are known as gravel pits. Southern England possesses particularly large concentrations of them due to the deposition of gravel in the region during the Ice Ages. As of 2006, the United States is the leading producer and consumer of gravel. The word gravel comes from the Breton language, adding the -el suffix in Breton denotes the component parts of something larger. Thus gravel means the stones which make up such a beach on the coast. Many dictionaries ignore the Breton language, citing Old French gravele or gravelle, Gravel often has the meaning a mixture of different size pieces of stone mixed with sand and possibly some clay. American English also allows small stones without sand mixed in also known as crushed stone, types of gravel include, Bank gravel, naturally deposited gravel intermixed with sand or clay found in and next to rivers and streams. Also known as Bank run or River run, bench gravel, a bed of gravel located on the side of a valley above the present stream bottom, indicating the former location of the stream bed when it was at a higher level. Creek rock, this is rounded, semi-polished stones, potentially of a wide range of types. It is also used as concrete aggregate and less often as a paving surface. Crushed stone, rock crushed and graded by screens and then mixed to a blend of stones and fines and it is widely used as a surfacing for roads and driveways, sometimes with tar applied over it. Crushed stone may be made from granite, limestone, dolomite, also known as crusher run, DGA QP, and shoulder stone
13.
Boulder
–
In geology, a boulder is a rock fragment with size greater than 25.6 centimetres in diameter. Smaller pieces are called cobbles and pebbles, while a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move, smaller boulders are usually just called rocks or stones. The word boulder is short for boulder stone, from Middle English bulderston or Swedish bullersten, in places covered by ice sheets during Ice Ages, such as Scandinavia, northern North America, and Siberia, glacial erratics are common. Erratics are boulders picked up by ice sheets during their advance and they are called erratic because they typically are of a different rock type than the bedrock on which they are deposited. One of them is used as the pedestal of the Bronze Horseman in Saint Petersburg, boulder sized clasts are found in some sedimentary rocks, such as coarse conglomerate and boulder clay. The climbing of large boulders is called bouldering, road debris Monolith Media related to Boulders at Wikimedia Commons
14.
Plucking (glaciation)
–
Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the erosion and transportation of individual pieces of bedrock, especially large joint blocks. This occurs in a type of glacier called a valley glacier, as a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints in the bedrock. This produces large pieces of rock called joint blocks, eventually these joint blocks come loose and become trapped in the glacier. In this way, plucking has been linked to regelation, rocks of all sizes can become trapped in the bottom of the glacier. Joint blocks up to three meters have been plucked and transported and these entrained rock fragments can also cause abrasion along the subsequent bedrock and walls. Plucking also leads to chatter marks, wedge shaped indentations left on the bedrock or other rock surfaces, glacial plucking both exploits pre-existing fractures in the bedrock and requires continued fracturing to maintain the cycle of erosion. Glacial plucking is most significant where the surface is well jointed or fractured or where it contains exposed bed planes, as this allows meltwater. Plucking of bedrock also occurs in upland rivers, and shares a number of similarities with glacial examples. Glacial plucking is largely dependent on the amount of stress exerted on a clast overlain by glacial ice and this relationship is a balance between the sheer stress exerted on the clast and the normal pressure on the clast by a body of ice. Plucking is increased where there are preexisting fractures in a rock bed, as the glacier slides down a mountain, energy from friction, pressure or geothermal heat causes glacial meltwater to infiltrate the spaces between rocks. This process, known as frost wedging, puts stress on the structure as water expands when it freezes. Impacts from large clasts carried in the bedload can cause stress to the bedrock. Glacial plucking is the mechanism of other small scale mechanical glacial erosion such as striation, abrasion. The heavier the sediment load, the extreme the erosion of the downhill landscape. Erosion is largely dependent on the amount of flow and its velocity. A rock that has been subject to glacial erosion will often show a pattern in which the rock appears scratched. Long parallel lines cover the rock and show the appearance of something having been dragged along the top of it. Although striations can form on any sort of rock, they are present on more stable bedrock such as quartzite or granite where erosion processes are more readily preserved
15.
Abrasion (geology)
–
Abrasion is the mechanical scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion. After friction, the moving particles dislodge loose and weak debris from the side of the rock, the intensity of abrasion depends on the hardness, concentration, velocity and mass of the moving particles. Coastal abrasion occurs as breaking waves which contain sand and larger fragments erode the shoreline or headland and this removes material resulting in undercutting and possible collapse of unsupported overhanging cliffs. Abrasion platforms are shore platforms where wave action abrasion is a prominent process, if it is currently being fashioned, it will be exposed only at low tide, but there is a possibility that the wave-cut platform will be hidden sporadically by a mantle of beach shingle. If the platform is exposed above the high-water mark, it is probably a raised beach platform. Erosion Glacial striation Sedimentary Marine terrace
16.
Clastic rock
–
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, clastic sedimentary rocks are rocks composed predominantly of broken pieces or clasts of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on size, clast and cementing material composition. The classification factors are often useful in determining a samples environment of deposition, an example clastic environment would be a river system in which the full range of grains being transported by the moving water consist of pieces eroded from solid rock upstream. Grain size varies from clay in shales and claystones, through silt in siltstones, sand in sandstones, the Krumbein phi scale numerically orders these terms in a logarithmic size scale. Siliciclastic rocks are clastic rocks that are composed almost exclusively of silicon. The composition of sedimentary rocks includes the chemical and mineralogical components of the framework as well as the cementing material that make up these rocks. Boggs divides them into four categories, major minerals, accessory minerals, rock fragments, major minerals can be categorized into subdivisions based on their resistance to chemical decomposition. Those that possess a great resistance to decomposition are categorized as stable, while those that do not are considered less stable, the most common stable mineral in siliciclastic sedimentary rocks is quartz. Quartz makes up approximately 65 percent of framework grains present in sandstones, less stable minerals present in this type of rocks are feldspars, including both potassium and plagioclase feldspars. Feldspars comprise a considerably lesser portion of framework grains and minerals and they only make up about 15 percent of framework grains in sandstones and 5% of minerals in shales. Clay mineral groups are present in mudrocks but can be found in other siliciclastic sedimentary rocks at considerably lower levels. Accessory minerals are associated with those whose presence in the rock are not directly important to the classification of the specimen and these generally occur in smaller amounts in comparison to the quartz, and feldspars. Furthermore, those that do occur are generally heavy minerals or coarse grained micas, rock fragments also occur in the composition of siliciclastic sedimentary rocks and are responsible for about 10 -15 percent of the composition of sandstone. They generally make up most of the gravel size particles in conglomerates, though they sometimes are, rock fragments are not always sedimentary in origin. They can also be metamorphic or igneous, chemical cements vary in abundance but are predominantly found in sandstones. The two major types, are based and carbonate based
17.
Sedimentary structures
–
Sedimentary structures are those structures formed during sediment deposition. There are two kinds of structures, bidirectional and unidirectional. Flow regimes in single-direction flow, which at varying speeds and velocities produce different structures, are called bedforms, in the lower flow regime, the natural progression is from a flat bed, to some sediment movement, to ripples, to slightly larger dunes. Dunes have a vortex in the lee side of the dune, as the upper flow regime forms, the dunes become flattened out, and then produce antidunes. At higher still velocity, the antidunes are flattened and most sedimentation stops, ripple marks usually form in conditions with flowing water, in the lower part of the Lower Flow Regime. There are two types of marks, Symmetrical ripple marks - Often found on beaches, they are created by a two way current, for example the waves on a beach. This creates ripple marks with pointed crests and rounded troughs, which arent inclined more to a certain direction, three common sedimentary structures that are created by these processes are herringbone cross-stratification, flaser bedding, and interference ripples. Asymmetrical ripple marks - These are created by a one way current, for example in a river and this creates ripple marks with still pointed crests and rounded troughs, but which are inclined more strongly in the direction of the current. For this reason, they can be used as palaeocurrent indicators, antidunes are the sediment bedforms created by fast, shallow flows of water with a Froude number greater than 1. Antidunes form beneath standing waves of water that periodically steepen, migrate, the antidune bedform is characterized by shallow foresets, which dip upstream at an angle of about ten degrees that can be up to five meters in length. They can be identified by their low angle foresets, for the most part, antidunes bedforms are destroyed during decreased flow, and therefore cross bedding formed by antidunes will not be preserved. A number of biologically-created sedimentary structures exist, called trace fossils, examples include burrows and various expressions of bioturbation. Ichnofacies are groups of fossils that together help give information on the depositional environment. In general, as deeper burrows become more common, the shallower the water, as surface traces become more common, the water becomes deeper. Microbes may also interact with sediment to form Microbially Induced Sedimentary Structures, soft-sediment deformation structures or SSD, is a consequence of the loading of wet sediment as burial continues after deposition. The heavier sediment squeezes the water out of the sediment due to its own weight. There are three variants of SSD, load structures or load casts are blobs that form when a denser, wet sediment slumps down on. Pseudonodules or ball-and-pillow structures, are pinched-off load structures, these may also be formed by earthquake energy, flame structures, fingers of mud that protrude into overlying sediments
18.
Matrix (geology)
–
The matrix or groundmass of rock is the finer-grained mass of material wherein larger grains, crystals or clasts are embedded. The matrix of an igneous rock consists of finer-grained, often microscopic and this porphyritic texture is indicative of multi-stage cooling of magma. For example, porphyritic andesite will have large phenocrysts of plagioclase in a fine-grained matrix, also in South Africa, diamonds are often mined from a matrix of weathered clay-like rock called yellow ground. The matrix of sedimentary rocks is finer-grained sedimentary material, such as clay or silt and it also used to describe the rock material in which a fossil is embedded. All sediments are at first in an incoherent condition, and in this state they may remain for an indefinite period. Millions of years have elapsed since some of the early Tertiary strata gathered on the floor, yet they are quite friable. The pressure of newer sediments on underlying masses is one cause of this change. More efficiency is generally ascribed to the action of percolating water, the redeposited cementing material is most commonly calcareous or siliceous. Limestones, which were originally a loose accumulation of shells, corals, the change of aragonite to calcite and of calcite to dolomite, by forming new crystalline masses in the interior of the rock, usually also accelerates consolidations. Silica is less soluble in ordinary waters, but even this ingredient of rocks is dissolved and redeposited with great frequency. Others contain fine scales of kaolin or of mica, argillaceous materials may be compacted by mere pressure, like graphite and other scaly minerals
19.
Outwash plain
–
An outwash plain, also called a sandur, sandr or sandar, is a plain formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the rock surface. Sandurs are common in Iceland where geothermal activity accelerates the melting of ice flows, sandurs derive their name from Skeiðarársandur in Iceland, the largest outwash plain in the world with an area of 1,300 km2. Sandurs are found in glaciated areas, such as Svalbard, Kerguelen Islands, an outwash plain might contain surficial braided stream complexes that rework the original deposits. They may also contain kettle lakes, locations where blocks of ice have melted, sandurs are most common in Iceland, where geothermal activity beneath ice caps speeds up the deposition of sediment by meltwater. As well as regular geothermal activity, volcanic activity gives rise to large glacial bursts several times a century, the Gaspé Peninsula that makes up the essential part of southern Quebec also contains several example of paleo-sandar, dating from the Pleistocene ice melt. The original sandur from which the name is derived is Skeiðarársandur. Skeiðarársandur is the largest sandur in the world, covering an area of 1,300 km2, volcanic eruptions under the icecap have given rise to many large glacial bursts, most recently in 1996, when the Ring Road was washed away. This road, which encircles Iceland and was completed in 1974, has since been repaired. The 1996 jökulhlaup was caused by the eruption of the Grímsvötn volcano, net deposition of sediment was estimated to be 12,800,000 m3. The main braided channels of Skeiðarársandur are the Gígjukvísl and Skeiðará rivers, in the Gígjukvísl there was massive sediment deposition of up to 12 m, which occurred closest to the terminus of the glacier. The erosional patterns of Skeiðarársandur can be seen by looking at the elevation differences measured with repeat-pass laser altimetry flown in 1996,1997. Of the overall deposition during the 1996 jökulhlaup, nearly half of the net gain had been eroded 4 years after the flood and these two rivers on the sandur display drastically different erosional patterns. The Gígjukvísl river is some of the highest level of sediment deposit occurred. This indicates that these massive jökulhlaup deposits may have a large impact in the short term. However, in order to have sustained active accretion across the entire sandur there needs to be a diffuse, kankakee Outwash Plain Terminal moraine Church, Michael A. Baffin Island sandurs, a study of arctic fluvial processes. Garvin J. B. Topographic Dynamics of Kerguelen Island, A Preliminary SRTM Analysis, American Geophysical Union, Fall Meeting 2001 Gomez B. Russell A. J. Knudsen O. Sediment Distribution on Skeidararsandur, Southeast Iceland, American Geophysical Union, glacial Outburst Floods in Iceland, EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6–11 April 2003 Magilligan F. J. Gomez B
20.
River
–
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water, small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the term river as applied to geographic features. Many names for small rivers are specific to geographic location, examples are run in parts of the United States, burn in Scotland and northeast England. Sometimes a river is defined as being larger than a creek, but not always, Rivers are part of the hydrological cycle. Potamology is the study of rivers while limnology is the study of inland waters in general. Extraterrestrial rivers of liquid hydrocarbons have recently found on Titan. Channels may indicate past rivers on other planets, specifically outflow channels on Mars and rivers are theorised to exist on planets, a river begins at a source, follows a path called a course, and ends at a mouth or mouths. The water in a river is confined to a channel. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be wide in relation to the size of the river channel. This distinction between river channel and floodplain can be blurred, especially in areas where the floodplain of a river channel can become greatly developed by housing. Rivers can flow down mountains, through valleys or along plains, the term upriver refers to the direction towards the source of the river, i. e. against the direction of flow. Likewise, the term describes the direction towards the mouth of the river. The term left bank refers to the bank in the direction of flow. The river channel typically contains a stream of water, but some rivers flow as several interconnecting streams of water. Extensive braided rivers are now found in only a few regions worldwide and they also occur on peneplains and some of the larger river deltas. Anastamosing rivers are similar to braided rivers and are quite rare
21.
Proglacial lake
–
At the end of the last ice age approximately 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere. In some cases, such lakes gradually evaporated during the period after the Quaternary ice age. Good examples of structures can be found in the Channeled Scablands of eastern Washington. In Great Britain, Lake Lapworth, Lake Harrison and Lake Pickering were examples of proglacial lakes, the receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are. Several such lakes have formed rapidly during the 20th century and these lakes may burst, creating a hazard for zones below. Many natural dams containing the water have been reinforced with safety dams. Some 34 such dams have been built in the Cordillera Blanca to contain proglacial lakes, several proglacial lakes have also formed in recent decades at the end of glaciers on the eastern side of New Zealands Southern Alps. The most accessible, Lake Tasman, hosts boat trips for tourists, list of prehistoric lakes Pluvial lake Proglacial lakes of Minnesota
22.
Gemstone
–
A gemstone is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks or organic materials that are not minerals are used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone, apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter, a worker is a diamantaire. The carvings of Carl Fabergé are significant works in this tradition, the traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious, similar distinctions are made in other cultures. In modern usage the precious stones are diamond, ruby, sapphire, other stones are classified by their color, translucency and hardness. Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone, in modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition, for example, diamonds are made of carbon and rubies of aluminium oxide. Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic, another term used is habit, the form the gem is usually found in. For example, diamonds, which have a crystal system, are often found as octahedrons. Gemstones are classified into different groups, species, and varieties, for example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the Emerald, aquamarine, red beryl, goshenite, heliodor, and morganite, gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and luster. They may exhibit pleochroism or double refraction and they may have luminescence and a distinctive absorption spectrum. Material or flaws within a stone may be present as inclusions, gemstones may also be classified in terms of their water. This is a grading of the gems luster, transparency. Very transparent gems are considered first water, while second or third water gems are those of a lesser transparency, there is no universally accepted grading system for gemstones. Diamonds are graded using a system developed by the Gemological Institute of America in the early 1950s, historically, all gemstones were graded using the naked eye
23.
Ore
–
An ore is a type of rock that contains sufficient minerals with important elements including metals that can be economically extracted from the rock. The ores are extracted from the earth through mining, they are refined to extract the valuable element. The grade or concentration of an ore mineral, or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the value contained in the rock to determine what ore can be processed. Metal ores are generally oxides, sulfides, silicates, or native metals that are not commonly concentrated in the Earths crust, the ores must be processed to extract the metals of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes, the process of ore formation is called ore genesis. An ore deposit is an accumulation of ore and this is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type, Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. Stratiform arkose-hosted and shale-hosted copper, typified by the Zambian copperbelt and this identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. This is because the distribution of ores is unequal and dislocated from locations of peak demand. Other, lesser, commodities do not have international clearing houses and benchmark prices and this generally makes determining the price of ores of this nature opaque and difficult. Such metals include lithium, niobium-tantalum, bismuth, antimony and rare earths, most of these commodities are also dominated by one or two major suppliers with >60% of the worlds reserves. The London Metal Exchange aims to add uranium to its list of metals on warrant, the World Bank reports that China was the top importer of ores and metals in 2005 followed by the USA and Japan. Economic geology Mineral resource classification Ore genesis Petrology Froth Flotation Extractive metallurgy DILL, the “chessboard” classification scheme of mineral deposits, Mineralogy and geology from aluminum to zirconium, Earth-Science Reviews, Volume 100, Issue 1-4, June 2010, Pages 1-420
24.
Diamond
–
Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, yellow, brown, green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle. Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, proper, unalterable, unbreakable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history, later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
25.
U.S. state
–
A U. S. state is a constituent political entity of the United States of America. There are 50 states, which are together in a union with each other. Each state holds administrative jurisdiction over a geographic territory. Due to the shared sovereignty between each state and the government, Americans are citizens of both the federal republic and of the state in which they reside. State citizenship and residency are flexible, and no government approval is required to move between states, except for persons covered by certain types of court orders. States range in population from just under 600,000 to over 39 million, four states use the term commonwealth rather than state in their full official names. States are divided into counties or county-equivalents, which may be assigned some local authority but are not sovereign. County or county-equivalent structure varies widely by state, State governments are allocated power by the people through their individual constitutions. All are grounded in principles, and each provides for a government. States possess a number of powers and rights under the United States Constitution, Constitution has been amended, and the interpretation and application of its provisions have changed. The general tendency has been toward centralization and incorporation, with the government playing a much larger role than it once did. There is a debate over states rights, which concerns the extent and nature of the states powers and sovereignty in relation to the federal government. States and their residents are represented in the federal Congress, a legislature consisting of the Senate. Each state is represented in the Senate by two senators, and is guaranteed at least one Representative in the House, members of the House are elected from single-member districts. Representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census, the Constitution grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has expanded from the original 13 to 50, alaska and Hawaii are the most recent states admitted, both in 1959. The Constitution is silent on the question of states have the power to secede from the Union. Shortly after the Civil War, the U. S. Supreme Court, in Texas v. White, as a result, while the governments of the various states share many similar features, they often vary greatly with regard to form and substance
26.
Wisconsin
–
Wisconsin is a U. S. state located in the north-central United States, in the Midwest and Great Lakes regions. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, Wisconsin is the 23rd largest state by total area and the 20th most populous. The state capital is Madison, and its largest city is Milwaukee, the state is divided into 72 counties. Wisconsin is second to Michigan in the length of its Great Lakes coastline, Wisconsin is known as Americas Dairyland because it is one of the nations leading dairy producers, particularly famous for its cheese. Manufacturing, especially paper products, information technology, and tourism are major contributors to the states economy. The word Wisconsin originates from the given to the Wisconsin River by one of the Algonquian-speaking Native American groups living in the region at the time of European contact. French explorer Jacques Marquette was the first European to reach the Wisconsin River, arriving in 1673, subsequent French writers changed the spelling from Meskousing to Ouisconsin, and over time this became the name for both the Wisconsin River and the surrounding lands. English speakers anglicized the spelling from Ouisconsin to Wisconsin when they began to arrive in numbers during the early 19th century. The legislature of Wisconsin Territory made the current spelling official in 1845, the Algonquin word for Wisconsin and its original meaning have both grown obscure. Interpretations vary, but most implicate the river and the red sandstone that lines its banks, other theories include claims that the name originated from one of a variety of Ojibwa words meaning red stone place, where the waters gather, or great rock. Wisconsin has been home to a variety of cultures over the past 12,000 years. The first people arrived around 10,000 BCE during the Wisconsin Glaciation and these early inhabitants, called Paleo-Indians, hunted now-extinct ice age animals such as the Boaz mastodon, a prehistoric mastodon skeleton unearthed along with spear points in southwest Wisconsin. After the ice age ended around 8000 BCE, people in the subsequent Archaic period lived by hunting, fishing, agricultural societies emerged gradually over the Woodland period between 1000 BCE to 1000 CE. Toward the end of period, Wisconsin was the heartland of the Effigy Mound culture. Later, between 1000 and 1500 CE, the Mississippian and Oneota cultures built substantial settlements including the village at Aztalan in southeast Wisconsin. The Oneota may be the ancestors of the modern Ioway and Ho-Chunk tribes who shared the Wisconsin region with the Menominee at the time of European contact, the first European to visit what became Wisconsin was probably the French explorer Jean Nicolet. He canoed west from Georgian Bay through the Great Lakes in 1634, pierre Radisson and Médard des Groseilliers visited Green Bay again in 1654–1666 and Chequamegon Bay in 1659–1660, where they traded for fur with local Native Americans. In 1673, Jacques Marquette and Louis Jolliet became the first to record a journey on the Fox-Wisconsin Waterway all the way to the Mississippi River near Prairie du Chien
27.
Indiana
–
Indiana /ɪndiˈænə/ is a U. S. state located in the midwestern and Great Lakes regions of North America. Indiana is the 38th largest by area and the 16th most populous of the 50 United States and its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th U. S. state on December 11,1816, before becoming a territory, varying cultures of indigenous peoples and historic Native Americans inhabited Indiana for thousands of years. Indiana has an economy with a gross state product of $298 billion in 2012. Indiana has several areas with populations greater than 100,000. The states name means Land of the Indians, or simply Indian Land and it also stems from Indianas territorial history. On May 7,1800, the United States Congress passed legislation to divide the Northwest Territory into two areas and named the section the Indiana Territory. In 1816, when Congress passed an Enabling Act to begin the process of establishing statehood for Indiana, a resident of Indiana is officially known as a Hoosier. The first inhabitants in what is now Indiana were the Paleo-Indians, divided into small groups, the Paleo-Indians were nomads who hunted large game such as mastodons. They created stone tools made out of chert by chipping, knapping and flaking, the Archaic period, which began between 5000 and 4000 BC, covered the next phase of indigenous culture. The people developed new tools as well as techniques to cook food, such new tools included different types of spear points and knives, with various forms of notches. They made ground-stone tools such as axes, woodworking tools. During the latter part of the period, they built mounds and middens. The Archaic period ended at about 1500 BC, although some Archaic people lived until 700 BC, afterward, the Woodland period took place in Indiana, where various new cultural attributes appeared. During this period, the people created ceramics and pottery, an early Woodland period group named the Adena people had elegant burial rituals, featuring log tombs beneath earth mounds. In the middle portion of the Woodland period, the Hopewell people began developing long-range trade of goods, nearing the end of the stage, the people developed highly productive cultivation and adaptation of agriculture, growing such crops as corn and squash. The Woodland period ended around 1000 AD, the Mississippian culture emerged, lasting from 1000 until the 15th century, shortly before the arrival of Europeans. During this stage, the people created large urban settlements designed according to their cosmology, with mounds and plazas defining ceremonial
28.
Canada
–
Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto, Montreal and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Edmonton, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada. With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military. While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, later that year, the name of national holiday was changed from Dominion Day to Canada Day
29.
Prospecting
–
Prospecting is the first stage of the geological analysis of a territory. It is the search for minerals, fossils, precious metals or mineral specimens. Prospecting is a form of mineral exploration which is an organised. Prospecting is physical labour, involving traversing, panning, sifting and outcrop investigation, in other areas publicly held lands are open to prospecting without staking a mining claim. In the case of gold, all streams in an area would be panned at the appropriate trap sites looking for a show of colour or gold in the river trail. For most base metal shows, the rock would have been mined by hand and crushed on site, often, these shows were short-lived, exhausted and abandoned quite soon, requiring the prospector to move onwards to the next and hopefully bigger and better show. Occasionally, though, the prospector would strike it rich and be joined by other prospectors, although these are thought of as old prospecting methods, these techniques are still used today but usually coupled with more advanced techniques such as geophysical magnetic or gravity surveys. In most countries in the 19th and early 20th century, it was unlikely that a prospector would retire rich even if he was the one who found the greatest of lodes. For instance Patrick Hannan, who discovered the Golden Mile, Kalgoorlie, the same story repeated at Bendigo, Ballarat, Klondike and California. In the United States and Canada prospectors were lured by the promise of gold, silver and they traveled across the mountains of the American West, carrying picks, shovels and gold pans. The majority of early prospectors had no training and relied mainly on luck to discover deposits, other gold rushes occurred in Papua New Guinea, Australia at least four times, and in South Africa and South America. In all cases, the rush was sparked by idle prospecting for gold and minerals which. Modern prospectors today rely on training, the study of geology, knowledge of previous prospecting in an area helps in determining location of new prospective areas. Prospecting includes geological mapping, rock assay analysis, and sometimes the intuition of the prospector, prospecting pickaxes are used to scrape at rocks and minerals, obtaining small samples that can be tested for trace amounts of ore. Modern prospecting pickaxes are also equipped with magnets, to aid in the gathering of ferromagnetic ores. Prospecting pickaxes are usually equipped with a head, with a very sharp point
30.
Kimberlite
–
Kimberlite is an igneous rock best known for sometimes containing diamonds. Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes as well as igneous dykes, Kimberlite also occurs as horizontal sills. Kimberlite pipes are the most important source of mined diamonds today, the consensus on kimberlites is that they are formed deep within the mantle. It is this depth of melting and generation which makes kimberlites prone to hosting diamond xenocrysts, despite its relative rarity, kimberlite has attracted attention because it serves as a carrier of diamonds and garnet peridotite mantle xenoliths to the Earths surface. Many kimberlite structures are emplaced as carrot-shaped, vertical intrusions termed pipes, Kimberlite classification is based on the recognition of differing rock facies. These differing facies are associated with a style of magmatic activity, namely crater, diatreme. The morphology of kimberlite pipes, and their classical carrot shape is the result of explosive volcanism from very deep mantle-derived sources. These volcanic explosions produce vertical columns of rock rise from deep magma reservoirs. The morphology of kimberlite pipes is varied but includes a sheeted dyke complex of tabular, within 1. 5–2 km of the surface, the highly pressured magma explodes upwards and expands to form a conical to cylindrical diatreme, which erupts to the surface. The surface expression is rarely preserved but is similar to a maar volcano. The diameter of a pipe at the surface is typically a few hundred meters to a kilometer. Two Jurassic kimberlite dikes exist in Pennsylvania, one, the Gates-Adah Dike, outcrops on the Monongahela River on the border of Fayette and Greene Counties. The other, the Dixonville-Tanoma Dike in central Indiana County, does not outcrop at the surface and was discovered by miners, similarly aged kimberlite is found in several locations in New York Both the location and origin of kimberlitic magmas are subjects of contention. The mechanism of enrichment has also been the topic of interest with models including partial melting, historically, kimberlites have been classified into two distinct varieties termed basaltic and micaceous based primarily on petrographic observations. This was later revised by Smith who renamed these divisions Group I and Group II based on the affinities of these rocks using the Nd, Sr. Mitchell later proposed that these group I and II kimberlites display such distinct differences and he showed that Group II kimberlites show closer affinities to lamproites than they do to Group I kimberlites. Hence, he reclassified Group II kimberlites as orangeites to prevent confusion, olivine lamproites were previously called Group II kimberlite or orangeite in response to the mistaken belief that they only occurred in South Africa. Their occurrence and petrology, however, are identical globally and should not be referred to as kimberlite
31.
Sedimentary rock
–
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 also 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 also 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, geomorphology, geochemistry, sedimentary rocks have also 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, feldspar, 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, sand, and mud and this tripartite subdivision is mirrored by the broad categories of rudites, arenites, and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape, conglomerates 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
32.
Atlantic Ocean
–
The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa. The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays, gulfs, and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
33.
Continental drift
–
Continental drift is the movement of the Earths continents relative to each other, thus appearing to drift across the ocean bed. The speculation that continents might have drifted was first put forward by Abraham Ortelius in 1596, the concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by some for lack of a mechanism and others because of prior theoretical commitments. The idea of continental drift has been subsumed by the theory of plate tectonics, W. J. Kious described Ortelius thoughts in this way, Abraham Ortelius in his work Thesaurus Geographicus. Suggested that the Americas were torn away from Europe and Africa, by earthquakes and floods and went on to say, The vestiges of the rupture reveal themselves, if someone brings forward a map of the world and considers carefully the coasts of the three. In his Manual of Geology,1863, Dana says The continents, Dana was enormously influential in America – his Manual of Mineralogy is still in print in revised form – and the theory became known as Permanence theory. This suggested that the oceans were a permanent feature of the earths surface and this led Mantovani to propose an Expanding Earth theory which has since been shown to be incorrect. Continental drift without expansion was proposed by Frank Bursley Taylor, who suggested in 1908 that the continents were moved into their present positions by a process of continental creep. Wegener said that of all theories, Taylors, although not fully developed, had the most similarities to his own. In the mid-20th century, the theory of drift was referred to as the Taylor-Wegener hypothesis. Alfred Wegener first presented his hypothesis to the German Geological Society on January 6,1912 and his hypothesis was that the continents had once formed a single landmass, called Pangea, before breaking apart and drifting to their present locations. Wegener was the first to use the continental drift and formally publish the hypothesis that the continents had somehow drifted apart. Although he presented evidence for continental drift, he was unable to provide a convincing explanation for the physical processes which might have caused this drift. The Polflucht hypothesis was studied by Paul Sophus Epstein in 1920. The theory of drift was not accepted for many years. One problem was that a driving force was missing. A second problem was that Wegeners estimate of the velocity of continental motion,250 cm/year, was implausibly high, and it did not help that Wegener was not a geologist. Other geologists also believed that the evidence that Wegener had provided was not sufficient, the British geologist Arthur Holmes championed the theory of continental drift at a time when it was deeply unfashionable. He proposed in 1931 that the Earths mantle contained convection cells that dissipated radioactive heat and his Principles of Physical Geology, ending with a chapter on continental drift, was published in 1944
34.
Precambrian
–
The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
35.
Snowball Earth
–
The Snowball Earth hypothesis proposes that Earths surface became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya. A number of unanswered questions remain, including whether the Earth was a full snowball, the snowball Earth episodes occurred before the sudden radiation of multicellular bioforms, known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity, in the 1960s, Mikhail Budyko, a Russian climatologist, developed a simple energy-balance climate model to investigate the effect of ice cover on global climate. While Budykos model showed that this ice-albedo stability could happen, he concluded that it had in fact never happened, in 1971, Aron Faegre, an American physicist, showed that a similar energy-balance model predicted three stable global climates, one of which was snowball earth. This model introduced Edward Norton Lorenzs concept of intransitivity indicating that there could be a jump from one climate to another. The term snowball Earth was coined by Joseph Kirschvink in a paper published in 1992 within a lengthy volume concerning the biology of the Proterozoic eon. Franklyn Van Houtens discovery of a consistent geological pattern in which lake levels rose, interest in the notion of a snowball Earth increased dramatically after Paul F. The snowball Earth hypothesis was originally devised to explain geological evidence for the apparent presence of glaciers at tropical latitudes, according to modelling, an ice-albedo feedback would result in glacial ice rapidly advancing to the equator once the glaciers spread to within 25° to 30° of the equator. Therefore, the presence of deposits within the tropics suggests global ice cover. Critical to an assessment of the validity of the theory, therefore, is an understanding of the reliability and significance of the evidence that led to the belief that ice ever reached the tropics. This evidence must prove two things, that a bed contains sedimentary structures that could have been created only by glacial activity and this last point is very difficult to prove. The best that can be done is to estimate the age of the rocks using radiometric methods, the first two points are often the source of contention on a case-to-case basis. Many glacial features can also be created by means. The snowball Earth hypothesis was first posited to explain what were considered to be glacial deposits near the equator. Since tectonic plates move slowly over time, ascertaining their position at a point in Earths long history is not easy. In addition to considerations of how the recognizable landmasses could have fit together, when sedimentary rocks form, magnetic minerals within them tend to align themselves with the Earths magnetic field. Through the precise measurement of this palaeomagnetism, it is possible to estimate the latitude where the matrix was formed. This palaeomagnetic location of glacial sediments has been taken to suggest that glaciers extended from land to sea level in tropical latitudes at the time the sediments were deposited
36.
Boulder clay
–
Boulder clay, in geology, is a deposit of clay, often full of boulders, which is formed out of the ground moraine material of glaciers and ice-sheets wherever they are found. It was the deposit of the Glacial Period in northern Europe. Boulder clay is known as till. Boulder clay is distinguished from other clay in that it contains more boulders, the clay is scraped from the top layer of older rock by the movement of a glacier or ice sheet. An ice sheet pushes rocks, boulders and everything else in its path, which in turn wears the rock into silt-like grain, much boulder clay is of a bluish-grey until exposed to weather, which transforms it to a brown colour. Boulder clay is classed with a group of poorly sorted materials and it is usually a stiff, tough clay devoid of stratification, though some varieties are distinctly laminated. Occasionally, within the clay, there are irregular lenticular masses of more or less stratified sand. The boulders are held within the clay in an irregular manner, usually they are somewhat oblong, and often they possess a flat side or sole, they may be angular, sub-angular, or well-rounded. If they are hard rocks, they frequently bear grooves and scratches caused by contact with other rocks while held firmly in the glacier ice. They may consist of any hard rock, with the exception of foraminifera, which have been found in the boulder clay of widely separated regions, fossils are practically unknown. In some maritime districts, marine shells have been incorporated with the clay, a classic example of boulder clay can be seen in England at the rapidly eroding cliffs of Hornsea, situated along the Holderness coast in East Yorkshire
.jpg)
