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43-547: Missiquoi is also the name of a 17th-century Abenaki village in northern Vermont, for which the sub-tribe was named. The name Missisquoi comes from mazipskoiak meaning "flint people," which comes from mazipskoik or "at the flint," meaning a chert quarry near what is now Swanton, Vermont . It's also spelled Missiassik or Masipskoik a word that means "where there are many big rocks or boulder" in Abenaki . Prior to European contact, some Western Abenaki founded villages at

86-659: A Hertzian cone when struck with sufficient force. This results in conchoidal fractures, a characteristic of all minerals with no cleavage planes. In this kind of fracture, a cone of force propagates through the material from the point of impact, eventually removing a full or partial cone, like when a plate-glass window is struck by a small object such as an air gun projectile. The partial Hertzian cones produced during lithic reduction are called flakes , and exhibit features characteristic of this sort of breakage, including striking platforms , bulbs of force , and occasionally eraillures , which are small secondary flakes detached from

129-465: A naturalist , zoologist and the founding father of paleontology, along with other natural thinkers during the Age of Reason presented fossils as integral evidence in the changing views of natural philosophy at the time from the application of new mathematics and other emerging branches of science. This brought about the acceptance of paleontology as a true scientific discipline. This also greatly affected

172-448: A fraction of a micron to 20 microns, but most typically 8 to 10 microns. Chalcedony is a microfibrous variety of quartz, consisting of radiating bundles of very thin crystals about 100 microns long. Megaquartz is composed of equidimensional grains over 20 microns in size. Most chert is microcrystalline quartz with minor chalcedony and sometimes opal , but cherts range from nearly pure opal to nearly pure quartz chert. However, little opal

215-413: A microcrystalline form of silica composed mostly of bladed crystals of cristobalite and tridymite . Much opal-CT takes the form of lepispheres , which are clusters of bladed crystals about 10 microns in diameter. Opal-CT in turn transforms to microquartz. In deep ocean water, the transition to opal-CT occurs at a temperature of about 45 °C (113 °F) while the transition to microquartz occurs at

258-418: A source of dissolved silica, but they are sometimes found cutting across bedding surfaces, where the chert fills fossil burrows , fluid escape structures , or fractures. Nodules under a few centimeters in size tend to be egg-shaped, while larger nodules form irregular bodies with knobby surfaces. The outer few centimeters of large nodules may show desiccation cracks with secondary chert, which likely formed at

301-506: A spark that ignites a small reservoir containing black powder , discharging the firearm. Cherts can cause several 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. The other concern is that certain cherts undergo an alkali-silica reaction with high-alkali cements. This reaction leads to cracking and expansion of concrete and ultimately to failure of

344-870: A temperature of about 80 °C (176 °F). However, the transition temperature varies considerably, and the transition is hastened by the presence of magnesium hydroxide , which provides a nucleus for the recrystallization. Megaquartz forms at elevated temperatures typical of metamorphism . There is evidence that the variety of chert called porcelainite , which is characterized by a high content of opal-CT, recrystallizes at very shallow depths. The Caballos Novaculite of Texas also shows signs of very shallow water deposition, including shallow water sedimentary structures and evaporite pseudomorphs , which are casts of crystals of soluble minerals that could have formed only in near-surface conditions. This novaculate appears to have formed by replacement of carbonate fecal pellets by chert. Bedded cherts can be further subdivided by

387-531: Is a subdivision of paleontology called invertebrate paleontology . Fungi macrofossils include fungal bodies and filaments . Most fungi fossils are found in amber . Fungi fossils are under-researched compared to animal and plant fossils. Macrofossils of fungi are rarer and are more commonly found as microfossils. The study of these fossils is called paleomycology . Trace macrofossils are fossilized evidence of animal behavior . These may include tracks , burrows and dung ( coprolites ). Trace fossils are

430-531: Is based in Swanton, Vermont . The group applied for but was denied federal recognition as a Native American tribe in 2007. The summary of the proposed finding (PF) stated that "The SSA petitioner claims to have descended as a group mainly from a Western Abenaki Indian tribe, most specifically, the Missisquoi Indians" and went on to state: "However, the available evidence does not demonstrate that

473-865: Is devoid of any fossils. Chert varies greatly in color, from white to black, but is most often found as gray, brown, grayish brown and light green to rusty red and occasionally as dark green. Its color is an expression of trace elements present in the rock. Both red and green are most often related to traces of iron in its oxidized and reduced forms, respectively. In petrology , the term "chert" refers generally to all chemically precipitated sedimentary rocks composed primarily of microcrystalline , cryptocrystalline and microfibrous silica . Most cherts are nearly pure silica, with less than 5% other minerals (mostly calcite , dolomite , clay minerals , hematite , and organic matter.) However, cherts range from very pure cherts with over 99% silica content to impure nodular cherts with less than 65% silica content. Aluminium

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516-418: Is far below saturation, indicating that silica cannot normally be precipitated from seawater through inorganic processes. The silica is instead extracted from seawater by living organisms, such as diatoms, radiolarians, and glass sponges, which can efficiently extract silica even from very unsaturated water, and which are estimated to presently produce 12 cubic kilometers (2.9 cu mi) of opal per year in

559-885: Is little in the carbonate buildup zone itself. This may reflect dissolution of opal where carbonate is being actively deposited, a lack of siliceous organisms in these environments, or removal of siliceous skeletons by strong currents that redeposit the siliceous material in the deep basin. The silica in nodular chert likely precipitates as opal-A, based on internal banding in nodules, and may recrystallize directly to microquartz without first recrystallizing to opal-CT. Some nodular chert may precipitate directly as microquartz, due to low levels of supersaturation of silica. The banded iron formations of Precambrian age are composed of alternating layers of chert and iron oxides . Nonmarine cherts may form in saline alkaline lakes as thin lenses or nodules showing sedimentary structures suggestive of evaporite origin. Such cherts are forming today in

602-485: Is of only modest economic importance today as a source of silica (quartz sand being much more important.) However, chert deposits may be associated with valuable deposits of iron , uranium , manganese , phosphorite , and petroleum . 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 , quartzites , and other tool stones used in lithic reduction , chert fractures in

645-518: Is over 60 million years old. Opaline chert often contains visible fossils of diatoms , radiolarians , and glass sponge spicules . Chert is found in settings as diverse as hot spring deposits ( siliceous sinter ), banded iron formation ( jaspilite ), or alkaline lakes . However, most chert is found either as bedded chert or as nodular chert . Bedded chert is more common in Precambrian beds, but nodular chert became more common in

688-435: Is the most abundant minor element, followed by iron and manganese or potassium , sodium , and calcium . Extracrystalline water (tiny inclusions of water within and around the quartz grains) make up less than 1% of most cherts. The Folk classification divides chert into three textural categories. Granular microquartz is the component of chert consisting of roughly equidimensional quartz grains, ranging in size from

731-418: Is typically composed of the petrified remains of siliceous ooze , the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms , silicoflagellates , and radiolarians . Precambrian cherts are notable for the presence of fossil cyanobacteria . In addition to microfossils , chert occasionally contains macrofossils . However, some chert

774-419: Is uncertain, but they may form from fossil remains that are completely dissolved in fluids that then migrate to precipitate their silica load in a nearby bed. Eolian quartz has also been suggested as a source of silica for chert beds. Precambrian bedded cherts are common, making up 15% of middle Precambrian sedimentary rock, and may have been deposited nonbiologically in oceans more saturated in silica than

817-506: Is usually black to green in color, and the full sequence of beds may be several hundred meters thick. The shale is typically black shale, sometimes with pyrite , indicating deposition in an anoxic environment. Bedded chert is most often found in association with turbidites , deep water limestone , submarine volcanic rock , ophiolites , and mélanges on active margins of tectonic plates . Sedimentary structures are rare in bedded cherts. The typically high purity of bedded chert, like

860-659: The Cretaceous . Diatoms were the dominant siliceous organism responsible for extracting silica from seawater from the Jurassic and later. Radiolarite consists mostly of remains of radiolarians. When the remains are well-cemented with silica, it is known as radiolarian chert . Many show evidence of a deep-water origin, but some appear to have formed in water as shallow as 200 meters (660 ft), perhaps in shelf seas where upwelling of nutrient-rich deep ocean water support high organic productivity. Radiolarians dominated

903-1010: The Merrimack River and the Champlain Valley, moved north to the Saint-François River in Quebec, Canada . There they joined the local Odanak community of Abenaki people. After enduring French and English colonists, the Missisquoi withdrew from areas of conflict during the American Revolutionary War . Linguist and historian Gordon M. Day wrote, "After this war, the Western Abenakis did not return to any of their former locations in force but rather united or reunited with their brethren at Saint Francis." Some held on to land claims in

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946-600: The Phanerozoic as the total volume of chert in the rock record diminished. Bedded chert is rare after the early Mesozoic . Chert became moderately abundant during the Devonian and Carboniferous and again became moderately abundant from the Jurassic to the present. Bedded chert, also known as ribbon chert, takes the form of thinly bedded layers (a few centimeters to a meter in thickness ) of nearly pure chert separated by very thin layers of silica-rich shale . It

989-532: The teeth , skulls , and bones . Vertebrate macrofossils are used to reconstruct extinct animals, determine their behaviors and how they evolved. Well preserved body fossils are of particular use in helping to reassemble extinct animal body structures. Invertebrate macrofossils include remains such as shells , tests , faunal armor , and exoskeletons . The bodies of small and soft bodied invertebrates rarely fossilize. Meanwhile, large and hard bodied invertebrates more commonly fossilize. The study of these fossils

1032-760: The United States and even collected rent. In 1805, the British Crown deeded lands near Durham, Quebec, to Abenaki people who fled the American Revolutionary War; these lands became the Durham Reserve. By 1850, this group became part of the large St. Francis village (Odanak). The St. Francis-Sokoki Band of the Abenaki Nation of Missisquoi is state-recognized by Vermont and claim to be Missiquoi descendants. The group

1075-403: The alkaline Lake T'oo'dichi'. Chert may also form from replacement of calcrete in fossil soils ( paleosols ) by silica dissolved from overlying volcanic ash beds. The cryptocrystalline nature of chert, combined with its above average ability to resist weathering, recrystallization and metamorphism has made it an ideal rock for preservation of early life forms. For example: Chert

1118-548: The alkaline lakes of the East African Rift Valley . These lakes are characterized by sodium carbonate brines with very high pH that can contain as much as 2700 ppm silica. Episodes of runoff of fresh water into the lakes lowers the pH and precipitates the unusual sodium silicate minerals magadiite or kenyaite , After burial and diagenesis , these are altered to Magadi-type chert. The Morrison Formation contains Magadi-type chert that may have formed in

1161-549: The area. Such botanical macrofossil data provide a valuable complement to pollen and faunal data that can be used to reconstruct the prehistoric terrestrial environment. Algal macrofossils (for instance, brown kelp , sea lettuce and large stromatolites ) are increasingly used to analyze prehistoric marine and aquatic ecosystems . The study of these fossils is called paleobotany . Plant macrofossils are increasingly being used along with pollen microfossils to reconstruct past climates. Vertebrate macrofossils include

1204-420: The development of geology and stratigraphy as new schools of science. This led to other scientific thinkers like Charles Darwin , a naturalist, biologist and geologist , to begin using macrofossils of evidence in a new scientific discipline called evolutionary biology . Plant macrofossils include leaf , needle , cone , and stem debris; and can be used to identify types of plants formerly growing in

1247-408: The early 1970's'...." Chert Chert ( / tʃ ɜːr t / ) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz , the mineral form of silicon dioxide (SiO 2 ). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood . Chert

1290-558: The extraction of silica from seawater prior to the Jurassic. Spicularite is chert composed of spicules of glass sponges and other invertebrates. When densely cemented, it is known as spicular chert . They are found in association with glauconite -rich sandstone , black shale , clay -rich limestone , phosphorites , and other nonvolcanic rocks typical of water a few hundred meters deep. Some bedded cherts appear devoid of fossils even under close microscopic examination. Their origin

1333-419: The flake's bulb of force. When a chert stone is struck against an iron-bearing surface, sparks result. 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. A primary historic use of common chert and flint was for flintlock firearms , in which the chert striking a metal plate produces

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1376-490: The high purity of other chemically precipitated rock, points to deposition in areas where there is little influx of detrital sediments (such as river water laden with silt and clay particles.) Such impurities as are present include authigenic pyrite and hematite, formed in the sediments after they were deposited, in addition to traces of detrital minerals. Seawater typically contains between 0.01 and 11 parts per million (ppm) of silica, with around 1 ppm being typical. This

1419-484: The kinds of organisms that produced the silica skeletons. Diatomaceous chert consists of beds and lenses of diatomite which were converted during diagenesis into dense, hard chert. Beds of marine diatomaceous chert comprising strata several hundred meters thick have been reported from sedimentary sequences such as the Miocene Monterey Formation of California and occur in rocks as old as

1462-462: The material. There are numerous varieties of chert, classified based on their visible, microscopic and physical characteristics. Examples are: Other lesser used archaic terms for chert are firestone and silex. Macrofossil Macrofossils , also known as megafossils , are the preserved remnants of organic beings and their activities that are large enough to be visible without a microscope . The term macrofossil stands in opposition to

1505-606: The modern ocean. The high degree of silica saturation was due either to intense volcanic activity or to the lack of modern organisms that remove silica from seawater. Nodular chert is most common in limestone but may also be found in shales and sandstones. It is less common in dolomite . Nodular chert in carbonate rocks is found as oval to irregular nodules . These vary in size from powdery quartz particles to nodules several meters in size. The nodules are most typically along bedding planes or stylolite (dissolution) surfaces, where fossil organisms tended to accumulate and provided

1548-704: The mouth of the Missisquoi River . By the 17th century, Western Abenaki from across Lake Champlain consolidated into the main village at Missisquoi in northern Vermont , so historians began to use the term "Missisquoi tribe" for all Champlain Valley Abenakis. The Sokoki people, who had lived along the Connecticut River , founded Odanak, also known as the village of St. Francis in Quebec. The Western Abenakis, including those living along

1591-424: The ocean bottom and are buried, forming siliceous ooze that is 30% to 60% silica. Thus, bedded cherts are typically composed mostly of fossil remains of organisms that secrete silica skeletons, which are usually altered by solution and recrystallization. The skeletons of these organisms are composed of opal-A, an amorphous form of silica, lacking long-range crystal structure. This is gradually transformed to opal-CT,

1634-557: The petitioner or its claimed ancestors descended from the St. Francis Indians of Quebec, a Missiquoi Abenaki entity in Vermont, any other Western Abenaki group, or an Indian entity from New England or Canada. Instead, the PF concluded that the petitioner is a collection of individuals of claimed but undemonstrated Indian ancestry 'with little or no social or historical connection with each other before

1677-411: The same time as the nodule. Calcareous fossils are occasionally present that have been completely silicified. Where chert occurs in chalk or marl , it is usually called flint . Nodular chert is often dark in color. It can have a white weathering rind that is known in archaeology as cortex . Most chert nodules have textures suggesting they were formed by diagenetic replacement, where silica

1720-423: The term microfossil . Microfossils, by contrast, require substantial magnification for evaluation by fossil -hunters or professional paleontologists . As a result, most fossils observed in the field and most specimens are macrofossils. Macrofossils come in many varieties and form in various ways depending on their environment and what is being fossilized including plant, fungi and animal remnants. The origins of

1763-423: The term macrofossil dates back to 1937 and was first used by G. D. Hanna, a US paleontologist and malacologist . Macrofossils have been subject to analysis since ancient times. Several Greek philosophers used fossilized shellfish to theorize the land was once covered by oceans. Macrofossils of body parts have been used to reconstruct extinct animals and provide basis for evolutionary lineages . Georges Cuvier ,

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1806-408: The world's oceans. Diatoms can double their numbers eight times a day under ideal conditions (though doubling once per day is more typical in normal seawater) and can extract silica from water with as little as 0.1 ppm silica. The organisms protect their skeletons from dissolution by "armoring" them with metal ions. Once the organisms die, their skeletons will quickly dissolve unless they accumulate on

1849-578: Was deposited in place of calcium carbonate or clay minerals . This may have taken place where meteoric water (water derived from snow or rain) mixed with saltwater in the sediment beds, where carbon dioxide was trapped, producing an environment supersaturated with silica and undersaturated with calcium carbonate. Nodular chert is particularly common in continental shelf environments. In the Permian Basin (North America) , chert nodules and chertified fossils are abundant in basin limestones, but there

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