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72-565: The Bécancour takes its source from the lake of the same name in the town of Thetford Mines , in the Chaudière-Appalaches region. It flows west into William Lake at Saint-Ferdinand , changes course northwards towards Inverness , turning westward there and continuing to flow west across the Centre-du-Québec region for most of its length. The river takes a turn northwestward at Saint-Wenceslas , finally emptying into

144-400: A (usually small) angle. Sometimes multiple sets of layers with different orientations exist in the same rock, a structure called cross-bedding . Cross-bedding is characteristic of deposition by a flowing medium (wind or water). The opposite of cross-bedding is parallel lamination, where all sedimentary layering is parallel. Differences in laminations are generally caused by cyclic changes in

216-525: A deep marine environment. They were raised during the Taconic orogeny . As for the St. Lawrence platform, it is composed of limestone , sandstone and mudrock undeformed;. The basin includes 378 plant species. In the plain downstream of the basin, the main forest species are gray birch , trembling aspen , white spruce and balsam fir . Peatlands encourage black spruce and tamarack . The Appalachian sector

288-424: A diagenetic structure common in carbonate rocks is a stylolite . Stylolites are irregular planes where material was dissolved into the pore fluids in the rock. This can result in the precipitation of a certain chemical species producing colouring and staining of the rock, or the formation of concretions . Concretions are roughly concentric bodies with a different composition from the host rock. Their formation can be

360-463: A particular sedimentary environment. Examples of bed forms include dunes and ripple marks . Sole markings, such as tool marks and flute casts, are grooves eroded on a surface that are preserved by renewed sedimentation. These are often elongated structures and can be used to establish the direction of the flow during deposition. Ripple marks also form in flowing water. There can be symmetric or asymmetric. Asymmetric ripples form in environments where

432-465: A red colour does not necessarily mean the rock formed in a continental environment or arid climate. The presence of organic material can colour a rock black or grey. Organic material is formed from dead organisms, mostly plants. Normally, such material eventually decays by oxidation or bacterial activity. Under anoxic circumstances, however, organic material cannot decay and leaves a dark sediment, rich in organic material. This can, for example, occur at

504-489: A rock is usually expressed with the Wentworth scale, though alternative scales are sometimes used. The grain size can be expressed as a diameter or a volume, and is always an average value, since a rock is composed of clasts with different sizes. The statistical distribution of grain sizes is different for different rock types and is described in a property called the sorting of the rock. When all clasts are more or less of

576-465: A sediment after its initial deposition. This includes compaction and lithification of the sediments. Early stages of diagenesis, described as eogenesis , take place at shallow depths (a few tens of meters) and is characterized by bioturbation and mineralogical changes in the sediments, with only slight compaction. The red hematite that gives red bed sandstones their color is likely formed during eogenesis. Some biochemical processes, like

648-431: A sedimentary rock may have been present in the original sediments or may formed by precipitation during diagenesis. In the second case, a mineral precipitate may have grown over an older generation of cement. A complex diagenetic history can be established by optical mineralogy , using a petrographic microscope . Carbonate rocks predominantly consist of carbonate minerals such as calcite, aragonite or dolomite . Both

720-516: A small-scale property of a rock, but determines many of its large-scale properties, such as the density , porosity or permeability . The 3D orientation of the clasts is called the fabric of the rock. The size and form of clasts can be used to determine the velocity and direction of current in the sedimentary environment that moved the clasts from their origin; fine, calcareous mud only settles in quiet water while gravel and larger clasts are moved only by rapidly moving water. The grain size of

792-952: A term for a fissile mudrock (regardless of grain size) although some older literature uses the term "shale" as a synonym for mudrock. Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue. Examples include: Chemical sedimentary rock forms when mineral constituents in solution become supersaturated and inorganically precipitate . Common chemical sedimentary rocks include oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite , baryte and gypsum . This fourth miscellaneous category includes volcanic tuff and volcanic breccias formed by deposition and later cementation of lava fragments erupted by volcanoes, and impact breccias formed after impact events . Alternatively, sedimentary rocks can be subdivided into compositional groups based on their mineralogy: Sedimentary rocks are formed when sediment

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864-417: A texture, only the average size of the crystals and the fabric are necessary. Most sedimentary rocks contain either quartz ( siliciclastic rocks) or calcite ( carbonate rocks ). In contrast to igneous and metamorphic rocks, a sedimentary rock usually contains very few different major minerals. However, the origin of the minerals in a sedimentary rock is often more complex than in an igneous rock. Minerals in

936-425: A valuable indicator of the biological and ecological environment that existed after the sediment was deposited. On the other hand, the burrowing activity of organisms can destroy other (primary) structures in the sediment, making a reconstruction more difficult. Secondary structures can also form by diagenesis or the formation of a soil ( pedogenesis ) when a sediment is exposed above the water level. An example of

1008-503: Is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension . This sediment is often formed when weathering and erosion break down a rock into loose material in a source area. The material is then transported from the source area to the deposition area. The type of sediment transported depends on the geology of the hinterland (the source area of the sediment). However, some sedimentary rocks, such as evaporites , are composed of material that form at

1080-629: Is a popular area for snowmobiling and four-wheel drive vehicles as well as for downhill and cross-country skiing. The city is home to the minor-pro ice hockey team the Thetford Mines Assurancia , who are members of the Ligue Nord-Américaine de Hockey (LNAH). They play home games at Centre Mario Gosselin . Thetford Mines is the only city to have hosted an LNAH team in every season since the league's 1996 inception. The city has ringette and hockey organisations for

1152-421: Is a structure where beds with a smaller grain size occur on top of beds with larger grains. This structure forms when fast flowing water stops flowing. Larger, heavier clasts in suspension settle first, then smaller clasts. Although graded bedding can form in many different environments, it is a characteristic of turbidity currents . The surface of a particular bed, called the bedform , can also be indicative of

1224-409: Is called bedding . Single beds can be a couple of centimetres to several meters thick. Finer, less pronounced layers are called laminae, and the structure a lamina forms in a rock is called lamination . Laminae are usually less than a few centimetres thick. Though bedding and lamination are often originally horizontal in nature, this is not always the case. In some environments, beds are deposited at

1296-588: Is divided into 45 municipalities and one Indian reserve . The largest municipality in the basin, Thetford Mines (26,190 inhabitants), has 41% of the population of this basin. Two other towns over 5000 inhabitants are Princeville and Plessisville . Bécancour is part of two geological provinces, namely the Appalachians upstream and the St. Lawrence Lowlands downstream. The Appalachians are composed of sedimentary rocks and volcanic which have been deposited in

1368-603: Is dominated by maple grove to yellow birch and maple grove to beech . The top of the mountains near Thetford Mines are favorable to white birch while at the bottom of the slopes we find balsam fir and tamarack. We find 66 species of fish in the Bécancour basin. The main species of interest for sport fishing are brook trout , brown trout , rainbow trout , Atlantic salmon , lake trout , northern pike , muskellunge , brown bullhead , rock bass , pumpkinseed , smallmouth bass , largemouth bass , perch and walleye . In

1440-429: Is higher when the sedimentation rate is high (so that a carcass is quickly buried), in anoxic environments (where little bacterial activity occurs) or when the organism had a particularly hard skeleton. Larger, well-preserved fossils are relatively rare. Fossils can be both the direct remains or imprints of organisms and their skeletons. Most commonly preserved are the harder parts of organisms such as bones, shells, and

1512-491: Is mirrored by the broad categories of rudites , arenites , and lutites , respectively, in older literature. The subdivision of these three broad categories is based on differences in clast shape (conglomerates and breccias), composition (sandstones), or grain size or texture (mudrocks). Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. Sandstone classification schemes vary widely, but most geologists have adopted

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1584-401: Is reduced. Sediments are typically saturated with groundwater or seawater when originally deposited, and as pore space is reduced, much of these connate fluids are expelled. In addition to this physical compaction, chemical compaction may take place via pressure solution . Points of contact between grains are under the greatest strain, and the strained mineral is more soluble than the rest of

1656-493: Is the most stable, followed by feldspar , micas , and finally other less stable minerals that are only present when little weathering has occurred. The amount of weathering depends mainly on the distance to the source area, the local climate and the time it took for the sediment to be transported to the point where it is deposited. In most sedimentary rocks, mica, feldspar and less stable minerals have been weathered to clay minerals like kaolinite , illite or smectite . Among

1728-609: Is the seat of Les Appalaches Regional County Municipality . The city is located in the Appalachian Mountains , 187 km east-northeast of Montreal and 79 km south of Quebec City . It is known mostly as the asbestos capital of Canada. Before European colonization , the Abenaki inhabited the Thetford Mines region. A village was founded in 1876 after the discovery of large asbestos deposits in

1800-420: The 2021 Census of Population conducted by Statistics Canada , Thetford Mines had a population of 26,072 living in 12,216 of its 13,059 total private dwellings, a change of 2.6% from its 2016 population of 25,403 . With a land area of 225.97 km (87.25 sq mi), it had a population density of 115.4/km (298.8/sq mi) in 2021. Given the abundance of snow for several months in winter, it

1872-579: The French Canadians and the Irish around the middle of the 19th century. However, the Appalachian region was transformed as early as 1876 with the discovery of asbestos . It was in 1905 that Thetford Mines , the most important city in the basin, was founded. Thetford Mines Thetford Mines ( Canada 2021 Census population 26,072) is a city in south-central Quebec , Canada. It

1944-596: The Noire River , the Bourbon River the Blanche River at Saint-Rosaire and another Blanche river at Saint-Wenceslas . The basin includes 62 lakes over one hectare (2.5 acres). In addition to Bécancour Lake (83 hectares [210 acres]), the river crosses Stater pond (8 hectares [20 acres]) and lakes à la Truite (135 hectares [330 acres]), William Lake (492 hectares [1,220 acres], the largest in

2016-630: The Saint Lawrence River near the heart of the city of Bécancour . The course of the Bécancour, which is 196 kilometres (122 mi), begins at 402 metres (1,319 ft) of altitude in the Appalachian Mountains . It has its source in Bécancour Lake , in the town of Thetford Mines . It follows a winding route to Lyster , which marks its entry into the St. Lawrence Lowlands . It then turns west-southwest to Daveluyville where it turns north-west to Bécancour where it flows into

2088-487: The estuary of Saint Lawrence . The watershed has an area of 2,620 kilometres (1,627.99 mi). Its modulus , which is measured at Maddington and comprises 84% of the basin, is 59 m3/s. Its average flood is 200 m3/s and its low water discharge is 25 m3/s. As for the extreme values recorded, they range from 1 to 500 m3/s. The city of Thetford Mines diverts part of the waters of the Saint-François basin for

2160-463: The history of life . The scientific discipline that studies the properties and origin of sedimentary 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 and structural geology . Sedimentary rocks can be subdivided into four groups based on

2232-682: The organic material of a dead organism undergoes chemical reactions in which volatiles such as water and carbon dioxide are expulsed. The fossil, in the end, consists of a thin layer of pure carbon or its mineralized form, graphite . This form of fossilisation is called carbonisation . It is particularly important for plant fossils. The same process is responsible for the formation of fossil fuels like lignite or coal. Structures in sedimentary rocks can be divided into primary structures (formed during deposition) and secondary structures (formed after deposition). Unlike textures, structures are always large-scale features that can easily be studied in

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2304-716: The 1695 map of Jean Deshayes. This name replaced the original names of Puante rivers (where the battle of the Puante River took place), and Saint-Michel. The toponym Rivière Bécancour was formalized on December 5, 1968, at the Commission de toponymie du Québec . It was around 1600 that the Abenakis settled at the mouth of the Wôlinaktekw . Most of the natives who settled there came from Namesokântsik (a place where there are many fish), now known as Mégantic , and from

2376-590: The 17th century, the river was originally known by European sattlers as the "Stinking River". Around 1600, some Abenaki families established themselves on the Puante River . The use continued during the first half of the 18th century. A map of the Province of Quebec from 1776 shows a "Gt. Puante River" and a " L. Puante River " north of it. A map of Canada from 1812 shows the Grand Puant River with

2448-686: The Abenakis from the region of the river Kennebec which circulated by Lake Mégantic . After several trips, they settled permanently in Wôlinak in 1735. The “Piste Bécancour” (Abenaki Becancour Trail), linked the Grand lac Saint François , via the Petit lac Saint-François (Ashberham) , in the canton of Coleraine, to the basin of the Bécancour River to Wôlinak. A village named "Wananoak" located near

2520-501: The Dott scheme, which uses the relative abundance of quartz, feldspar, and lithic framework grains and the abundance of a muddy matrix between the larger grains. Six sandstone names are possible using the descriptors for grain composition (quartz-, feldspathic-, and lithic-) and the amount of matrix (wacke or arenite). For example, a quartz arenite would be composed of mostly (>90%) quartz grains and have little or no clayey matrix between

2592-597: The World" and the "City of White Gold". In the boom times, there were seven mines operating in the area, employing 4,000 workers. In 1949 and in 1975, asbestos miners in Asbestos and Thetford Mines began strikes each lasting for almost five months which were the most violent labor conflicts in the history of Quebec. In 2001 the city expanded to its current boundaries, incorporating the nearby towns of Black Lake, Robertsonville, Pontbriand and Thetford-Sud. When Canada banned

2664-474: The accumulation or deposition of mineral or organic particles at Earth's surface , followed by cementation . Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment , and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from

2736-470: The activity of bacteria , can affect minerals in a rock and are therefore seen as part of diagenesis. Deeper burial is accompanied by mesogenesis , during which most of the compaction and lithification takes place. Compaction takes place as the sediments come under increasing overburden (lithostatic) pressure from overlying sediments. Sediment grains move into more compact arrangements, grains of ductile minerals (such as mica ) are deformed, and pore space

2808-554: The area. The village incorporated as Kingsville (named after William King, an important mine owner) in 1892. A few years later, in 1905, Kingsville was renamed after the Township of Thetford in which it was founded, which was named after the town of Thetford in Norfolk , England. During the 20th century, Thetford Mines became a hub for one of the world's largest asbestos-producing regions. back then being called "Asbestos Capital of

2880-404: The basin) and Joseph (243 hectares [600 acres]). As for wetlands, they cover 154 kilometres (95.69 mi), or 5.9% of the. Of these, the bogs covers 118 kilometres (73.32 mi) and the swamps 26 kilometres (16.16 mi). In 2008, the basin's population was estimated at 64354 inhabitants and had a density of 25 inhabitants per square kilometre (65/sq mi). The territory of the basin

2952-530: The benefit of Bécancour via its aqueduct , that is 19,000 cubic metres per day (7,800 cu ft/ks). This input, however, has a negligible effect on the river flow and represents less than 0.05 m3/s at Maddington. The river receives input from 87 watercourses. Its main tributaries are, from upstream to downstream, the rivière au Pin , the Bullard stream, the Palmer River (Bécancour River tributary) ,

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3024-399: The bottom of deep seas and lakes. There is little water mixing in such environments; as a result, oxygen from surface water is not brought down, and the deposited sediment is normally a fine dark clay. Dark rocks, rich in organic material, are therefore often shales. The size , form and orientation of clasts (the original pieces of rock) in a sediment is called its texture . The texture is

3096-504: The cement and the clasts (including fossils and ooids ) of a carbonate sedimentary rock usually consist of carbonate minerals. The mineralogy of a clastic rock is determined by the material supplied by the source area, the manner of its transport to the place of deposition and the stability of that particular mineral. The resistance of rock-forming minerals to weathering is expressed by the Goldich dissolution series . In this series, quartz

3168-421: The cement to produce secondary porosity . At sufficiently high temperature and pressure, the realm of diagenesis makes way for metamorphism , the process that forms metamorphic rock . The color of a sedimentary rock is often mostly determined by iron , an element with two major oxides: iron(II) oxide and iron(III) oxide . Iron(II) oxide (FeO) only forms under low oxygen ( anoxic ) circumstances and gives

3240-639: The continents of the Earth's crust is extensive (73% of the Earth's current land surface), but sedimentary rock is estimated to be only 8% of the volume of the crust. 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 often deposited in large structures called sedimentary basins . Sedimentary rocks have also been found on Mars . The study of sedimentary rocks and rock strata provides information about

3312-572: The current is in one direction, such as rivers. The longer flank of such ripples is on the upstream side of the current. Symmetric wave ripples occur in environments where currents reverse directions, such as tidal flats. Mudcracks are a bed form caused by the dehydration of sediment that occasionally comes above the water surface. Such structures are commonly found at tidal flats or point bars along rivers. Secondary sedimentary structures are those which formed after deposition. Such structures form by chemical, physical and biological processes within

3384-663: The dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel (>2 mm diameter), sand (1/16 to 2 mm diameter), and mud (<1/16 mm diameter). Mud is further divided into silt (1/16 to 1/256 mm diameter) and clay (<1/256 mm diameter). The classification of clastic sedimentary rocks parallels this scheme; conglomerates and breccias are made mostly of gravel, sandstones are made mostly of sand , and mudrocks are made mostly of mud. This tripartite subdivision

3456-515: The enjoyment of the season, with sporting events, concerts and fireworks. The same maples that produce syrup in spring, provide brilliant displays of colour in autumn. Two radio stations, CFJO ("O97,3") and CKLD ("Passion-Rock 105,5") serve Thetford Mines. Both stations air programming produced partially in Thetford Mines and partially in Victoriaville . Sedimentary rock Sedimentary rocks are types of rock that are formed by

3528-489: The field. Sedimentary structures can indicate something about the sedimentary environment or can serve to tell which side originally faced up where tectonics have tilted or overturned sedimentary layers. Sedimentary rocks are laid down in layers called beds or strata . A bed is defined as a layer of rock that has a uniform lithology and texture. Beds form by the deposition of layers of sediment on top of each other. The sequence of beds that characterizes sedimentary rocks

3600-404: The flow calms and the particles settle out of suspension . Most authors presently use the term "mudrock" to refer to all rocks composed dominantly of mud. Mudrocks can be divided into siltstones, composed dominantly of silt-sized particles; mudstones with subequal mixture of silt- and clay-sized particles; and claystones, composed mostly of clay-sized particles. Most authors use " shale " as

3672-485: The grain. As a result, the contact points are dissolved away, allowing the grains to come into closer contact. The increased pressure and temperature stimulate further chemical reactions, such as the reactions by which organic material becomes lignite or coal. Lithification follows closely on compaction, as increased temperatures at depth hasten the precipitation of cement that binds the grains together. Pressure solution contributes to this process of cementation , as

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3744-510: The grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc. Although the Dott classification scheme is widely used by sedimentologists, common names like greywacke , arkose , and quartz sandstone are still widely used by non-specialists and in popular literature. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles. These relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as

3816-587: The host rock. For example, a shell consisting of calcite can dissolve while a cement of silica then fills the cavity. In the same way, precipitating minerals can fill cavities formerly occupied by blood vessels , vascular tissue or other soft tissues. This preserves the form of the organism but changes the chemical composition, a process called permineralization . The most common minerals involved in permineralization are various forms of amorphous silica ( chalcedony , flint , chert ), carbonates (especially calcite), and pyrite . At high pressure and temperature,

3888-435: The lithologies dehydrates. Clay can be easily compressed as a result of dehydration, while sand retains the same volume and becomes relatively less dense. On the other hand, when the pore fluid pressure in a sand layer surpasses a critical point, the sand can break through overlying clay layers and flow through, forming discordant bodies of sedimentary rock called sedimentary dykes . The same process can form mud volcanoes on

3960-450: The mineral dissolved from strained contact points is redeposited in the unstrained pore spaces. This further reduces porosity and makes the rock more compact and competent . Unroofing of buried sedimentary rock is accompanied by telogenesis , the third and final stage of diagenesis. As erosion reduces the depth of burial, renewed exposure to meteoric water produces additional changes to the sedimentary rock, such as leaching of some of

4032-438: The place of deposition. The nature of a sedimentary rock, therefore, not only depends on the sediment supply, but also on the sedimentary depositional environment in which it formed. As sediments accumulate in a depositional environment, older sediments are buried by younger sediments, and they undergo diagenesis. Diagenesis includes all the chemical, physical, and biological changes, exclusive of surface weathering, undergone by

4104-627: The processes responsible for their formation: clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and a fourth category for "other" sedimentary rocks formed by impacts, volcanism , and other minor processes. Clastic sedimentary rocks are composed of rock fragments ( clasts ) that have been cemented together. The clasts are commonly individual grains of quartz , feldspar , clay minerals , or mica . However, any type of mineral may be present. Clasts may also be lithic fragments composed of more than one mineral. Clastic sedimentary rocks are subdivided according to

4176-480: The result of localized precipitation due to small differences in composition or porosity of the host rock, such as around fossils, inside burrows or around plant roots. In carbonate rocks such as limestone or chalk , chert or flint concretions are common, while terrestrial sandstones sometimes contain iron concretions. Calcite concretions in clay containing angular cavities or cracks are called septarian concretions . After deposition, physical processes can deform

4248-454: The rock a grey or greenish colour. Iron(III) oxide (Fe 2 O 3 ) in a richer oxygen environment is often found in the form of the mineral hematite and gives the rock a reddish to brownish colour. In arid continental climates rocks are in direct contact with the atmosphere, and oxidation is an important process, giving the rock a red or orange colour. Thick sequences of red sedimentary rocks formed in arid climates are called red beds . However,

4320-469: The same size, the rock is called 'well-sorted', and when there is a large spread in grain size, the rock is called 'poorly sorted'. The form of the clasts can reflect the origin of the rock. For example, coquina , a rock composed of clasts of broken shells, can only form in energetic water. The form of a clast can be described by using four parameters: Chemical sedimentary rocks have a non-clastic texture, consisting entirely of crystals. To describe such

4392-433: The sediment supply, caused, for example, by seasonal changes in rainfall, temperature or biochemical activity. Laminae that represent seasonal changes (similar to tree rings ) are called varves . Any sedimentary rock composed of millimeter or finer scale layers can be named with the general term laminite . When sedimentary rocks have no lamination at all, their structural character is called massive bedding. Graded bedding

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4464-402: The sediment, producing a third class of secondary structures. Density contrasts between different sedimentary layers, such as between sand and clay, can result in flame structures or load casts , formed by inverted diapirism . While the clastic bed is still fluid, diapirism can cause a denser upper layer to sink into a lower layer. Sometimes, density contrasts occur or are enhanced when one of

4536-443: The sediment. They can be indicators of circumstances after deposition. Some can be used as way up criteria . Organic materials in a sediment can leave more traces than just fossils. Preserved tracks and burrows are examples of trace fossils (also called ichnofossils). Such traces are relatively rare. Most trace fossils are burrows of molluscs or arthropods . This burrowing is called bioturbation by sedimentologists. It can be

4608-535: The solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement , which are called agents of denudation . Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies ( marine snow ). Sedimentation may also occur as dissolved minerals precipitate from water solution . The sedimentary rock cover of

4680-570: The sources of the river and a path leading to Lac Mégantic is inscribed on a Mitchell Map of 1755. The village is also described : Indian village of New France or Canada located near the shore and the source of the Puante river . As for the French, they began to settle in the plain of Bécancour in 1676. The Appalachian region was colonized by the British in the early 1800s. They were replaced by

4752-453: The subsurface that is useful for civil engineering , for example in the construction of roads , houses , tunnels , canals or other structures. Sedimentary rocks are also important sources of natural resources including coal , fossil fuels , drinking water and ores . The study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history , including palaeogeography , paleoclimatology and

4824-527: The three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remnants. Often these fossils may only be visible under magnification . Dead organisms in nature are usually quickly removed by scavengers , bacteria , rotting and erosion, but under exceptional circumstances, these natural processes are unable to take place, leading to fossilisation. The chance of fossilisation

4896-512: The top maple syrup producing regions in the world. In March and early April, local citizens often make a ritual outing to one of the area's sugar camps (or cabanes à sucre ) for sugaring off parties where maple syrup, reduced and thickened by slow boiling, is poured over fresh snow to create a delightful taffy. Summer brings a host of other outdoor activities. An abundance of lakes and rivers provide plenty of opportunities for outdoor gatherings and cool refreshment. A series of summer festivals add to

4968-542: The town of Bequencourt at its mouth and a smaller Puant River farther north. The Abenaki name it Wôlinaktekw which means "river at the bay". The Scottish who settled in Inverness named the section that passes through their territory "Thames River" (the Thames ). The present-day name of the river commemorates Pierre Robineau de Bécancour , 2e baron de Portneuf, lord of Bécancour (1654-1729). This name appeared on

5040-699: The use of asbestos in schools and homes, after using it for years as insulation, the mines of Thetford Mines largely exported their asbestos to areas such as southeast Asia, the Middle East, and South and Central America. However, in 2012, the city's last mine closed and Thetford Mines has developed other sectors, namely manufacturing. The city of Thetford Mines is the seat of the judicial district of Frontenac. The Köppen–Geiger climate classification system classifies its climate as humid continental (Dfb). Winters are very cold and snowy, while summers are warm and rainy when it receives more precipitation . In

5112-404: The woody tissue of plants. Soft tissue has a much smaller chance of being fossilized, and the preservation of soft tissue of animals older than 40 million years is very rare. Imprints of organisms made while they were still alive are called trace fossils , examples of which are burrows , footprints , etc. As a part of a sedimentary rock, fossils undergo the same diagenetic processes as does

5184-467: The youth, and there are yearly tournaments for ringette and minor Hockey players, as well as old-timers hockey tournaments. Thetford Mines was chosen as a top-five finalist for Kraft Hockeyville for 2009 on the February 21, 2009 Hockey Night In Canada " Hockey Day In Canada " special. Spring is maple syrup producing time in the area. The numerous stands of maple trees in the region makes it one of

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