Misplaced Pages

#50949

77-585: Although much of the High Atlas consists of sedimentary rocks, the Toubkal massif is an area of volcanic rocks which have weathered into alpine crests, cut by deep, narrow valleys. To the south, the mountain drops steeply down for 1,800 metres (5,906 ft) to a small lake called Lac d'Ifni. To the west, the mountain's edge is marked by a pass, the Tizi n'Ouanoums at 3,664 metres (12,021 ft). From this pass,

154-711: A terrorist act, after a video released on the Internet showed several of the suspects swearing allegiance to the Islamic State while decapitating Jespersen. Louisa Vesterager Jespersen (born 1994) grew up in Ikast , Denmark. She attended Vestre School, and became a student at the Ikast-Brande Gymnasium  [ da ] in 2013. She had been traveling to various countries, such as Argentina, Peru, and Norway. Jespersen applied for participation in

231-400: 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

308-501: A Moroccan killed people by driving his van into pedestrians in La Rambla in the 2017 Barcelona terrorist attacks , and the following day, another Moroccan killed two women and wounded 8 other victims in the 2017 Turku attack . On the morning of 17 December 2018, a pair of French hikers came across the decapitated bodies of the victims, and their tent, near a trail connecting Imlil to Mount Toubkal. A suspect named Abderrahim Khayali

385-424: 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

462-491: A long and pleasant traverse containing many gaps and towers. Some difficulties can be avoided by means of an abseil. Grade III/IV; 7 hours. On 17 December 2018, two trekkers , from Denmark and Norway, were murdered close to the foot of the trail in a terror-related attack. Sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface , followed by cementation . Sedimentation

539-463: 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

616-465: 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

693-489: 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

770-465: 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

847-431: 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

SECTION 10

#1732773119051

924-516: 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

1001-952: 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

1078-417: 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

1155-425: 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

1232-503: 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

1309-421: 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

1386-697: Is assumed to be the leader of the group, and the four men had shot a video the week before the murders, where they pledged allegiance to ISIS. The killers had agreed to carry out a terrorist act on either security services or foreign tourists, before deciding to travel to the Imlil region to look for foreigners, and where they would target the two backpackers. In the video of the killings, the attackers can be heard shouting "enemies of Allah", and "revenge for our brothers in Hajin ". Moroccan police later made additional arrests of individuals believed to have connections with

1463-409: 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

1540-429: 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

1617-491: 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

SECTION 20

#1732773119051

1694-401: 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

1771-562: Is still in effect in Morocco. In practice, no executions have taken place since 1993. As of 2024, the suspects are still awaiting execution. On 28 February 2023, Abderrahmane Khayali committed suicide by hanging with a piece of cloth taken from his clothes anchored to a window; he was awaiting execution at the local prison in Oujda . The remains of the victims were flown to Copenhagen , Denmark on 21 December 2018. Jespersen's funeral

1848-428: 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 the solidification of molten lava blobs erupted by volcanoes. The geological detritus

1925-493: 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

2002-449: 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

2079-630: The Atlas Mountains . The village of Imlil is popular with travellers as the main base for summiting Toubkal , which is the highest peak in North Africa . Four attackers had shared a video on social media before the attacks, pledging allegiance to the ISIS terror group, and discussed "destruction caused by the warplanes of the Crusader alliance ". One of the attackers stated, "Keep fighting

2156-678: The Fjällräven Polar expedition in 2017 and 2018. Maren Ueland (born 1990) was from Bryne , Norway. Jespersen and Ueland were students at the University of South-Eastern Norway , where they studied outdoor recreation and nature guidance to become tour guides. The pair had arrived in Morocco on 9 December as tourists, with the intention of trekking and "chasing experiences", according to Jespersen's mother. The two women first arrived in Marrakesh , before traveling to Imlil in

2233-463: 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

2310-682: 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

2387-501: 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

Toubkal - Misplaced Pages Continue

2464-594: The Islamic State in Syria , and was released in 2015. In July 2019, three of the suspects were given a death sentence , which their lawyer said he would appeal. On 31 October 2019, the death sentence for three of the convicted was upheld by the anti-terrorist court in Salé . In total, 24 suspects connected to the murders, or who were members of the jihadist cell, were sentenced. The prime suspect, Abdessamad Ejjoud,

2541-557: The Toubkal refuge, a path crosses the stream, climbs a steep scree slope to the east and enters a hanging valley , then climbs another steep slope to reach a col (Tizi'n'Toubkal at 3,940m). At the col the route turns left (northwards) up easy slopes to the narrow summit crest of Jebel Toubkal. The ascent during the summer (from May) is non-technical yet moderately difficult, complicated only by steep and slippery scree slopes and altitude sickness . Sturdy boots and proper (windproof) clothing are required, and trekking poles are helpful on

2618-453: The accused, and elevated one sentence from 15 to 20 years in prison. Ejjoud used his chance to speak before the sentence to ask for the death penalty, as he believed in neither the laws nor human rights. Ouaziyad and Afatti recited verses from the Quran . Like in the first trial, the court ordered the four prime suspects to pay 190,000 euros to the parents of Maren Ueland. The death penalty

2695-470: 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

2772-463: The bodies of Louisa Vesterager Jespersen , a 24-year-old Danish woman, and Maren Ueland , a 28-year-old Norwegian woman, were found decapitated in the foothills of Mount Toubkal near to the village of Imlil in the Atlas Mountains of Morocco . A total of 18 men have been arrested by Moroccan Police in relation to the murders. The murders were described by the Moroccan general prosecutor as

2849-399: 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

2926-504: 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

3003-421: 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

3080-639: 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

3157-572: 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

Toubkal - Misplaced Pages Continue

3234-663: 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

3311-406: The enemies of Allah , wherever you are, you have no excuse and, be informed that we are your supporters… you have allies among us". According to Swedish Defense University researcher Magnus Ranstorp , terrorists attacking tourists is not a new phenomenon, and it aims to destabilize the country where such attacks take place. While Morocco is generally seen as a secure destination for tourists,

3388-489: 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

3465-404: 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

3542-485: 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

3619-510: 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

3696-587: 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,

3773-512: The international press. Reactions in the native countries of the victims were of shock and outrage. A public torchlit vigil was held in Ueland's native town of Bryne in support of her family and loved ones. Vigils for the victims were held in Rabat , Morocco at the embassies of Norway and Denmark, along with vigils in Marrakesh and Imlil. Two videos, one depicting the murder, and another where

3850-610: The last terrorist attack happened in 2011, where 17 people were killed by a bombing at a restaurant in Marrakesh. Over 1,600 people have traveled from Morocco to join the Islamic State in the Syrian civil war . Moroccan authorities initially ignored the people who joined ISIS but later realized they could return to commit terrorist offenses in Morocco. As a result, the Bureau central d'investigation judiciaire  [ fr ] (BCIJ)

3927-435: 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

SECTION 50

#1732773119051

4004-450: 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

4081-625: The mountain's W-S-W ridge rises up to Toubkal West, which forms a shoulder at 4,020 metres (13,189 ft) before continuing to the summit at 4,167 metres (13,671 ft). The north and western sides of Toubkal drain down to the Mizane Valley, which has the passes of both Tizi n'Ouanoums and Tizi n'Ouagane at its head. Two hanging valleys on the western side of the mountain - the Ikhibi Nord and Ikhibi South provide ready access for trekkers and climbers to reach Toubkal's summit. At one time

4158-431: The mountains. It is a moderate hike and navigation is not a problem. The normal route starts with a walk to the village of Aroumd . Beyond Aroumd, a floodplain is crossed and the route follows the left slope of the valley southwards. The valley bends to the east to the tiny settlement of Sidi Chamharouch, which has grown around a Muslim shrine. At Sidi Chamharouch, the path leads over the stream and runs steeply uphill to

4235-596: The northern valley provided the normal route of ascent, but the construction of a mountain hut by the French Alpine Club below Ikhibi Sud now encourages trekkers to ascend via the southern route instead. Toubkal is popular with trekkers and ski mountaineers, but less so with climbers, despite its ease of access and sunny climate. Trekkers usually approach the mountain from Marrakesh via the road-end village of Imlil . Qualified guides can be hired, as well as porters, to carry equipment and food supplies higher into

4312-438: 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

4389-627: 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

4466-480: 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

4543-616: The right side of the Isougouane valley, which leads to two stone-built refuges (Refuge du Toubkal and Refuge Les Mouflons) that are often used as base camp at 3,207 m (10,522 ft). The first recorded ascent was on 12 June 1923 by the Marquis de Segonzac, Vincent Berger and Hubert Dolbeau, but the mountain may well have been climbed before that date. Toubkal's height was measured the following year, and determined as being 4,165 metres (13,665 ft) Nowadays measured at 4,167 metres,

4620-454: 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,

4697-469: 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

SECTION 60

#1732773119051

4774-421: The scree. An ice-axe may be needed on the remaining snowfields in the early summer. The ascent during the end of the winter and spring (February/March) is more difficult; crampons are necessary to ascend through the snow and - in some cases - ice. Ascent: 960 m (3,150 ft); 2.5 –3 hours. 2) Ikhibi Nord Not as frequently ascended as Ikhibi Sud, but technically easier. The route starts some distance down

4851-433: 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

4928-402: 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

5005-443: 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

5082-453: 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

5159-503: The summit is crowned with a large pyramidal metal trigonometric marker, and offers views taking in most of the Atlas and Little Atlas Mountains. It is possible to climb mountain Toubkal in two days - first day up to the refuge (around seven hours), second day to the summit (around four hours ascent, three hours descent) and back to Imlil (up to five hours). In summer the mountains can be very dry, but are sometimes subject to storms. Although

5236-425: The surface where they broke through upper layers. Sedimentary dykes can also be formed in a cold climate where the soil is permanently frozen during a large part of the year. Frost weathering can form cracks in the soil that fill with rubble from above. Such structures can be used as climate indicators as well as way up structures. Murders of Louisa Vesterager Jespersen and Maren Ueland On 17 December 2018,

5313-405: The suspects. In total, 24 went on trial in Salé , near Rabat in Morocco. Of those charged, 23 suspects are Moroccans from Marrakesh , and one is a Swiss-Spanish Muslim convert. Three of them were charged with murder, and the other 23 of various terrorist charges. In May 2019, one of the suspects admitted to killing one of the women. He had previously been jailed for having attempted to join

5390-413: The temperature should remain above zero during the day, freezing conditions are possible over 3,500m. In winter the mountains are covered in snow and ice, and can be prone to avalanches. Skiing is possible as the snow can lie to considerable depth and cover many rocky slopes. Information about the state of the route can be obtained at Marrakesh tourist offices or at Imlil. 1) Ikhibi Sud (normal route). From

5467-527: 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

5544-440: The valley from the Toubkal refuge, and turns right (eastwards) to follow a track up through a hanging valley to a col on the north side of Toubkal. Ascent:1,000 metres (3,281 ft); 3–4 hours. The col also gives access to adjacent peaks of Imouzzer 4,010 m (13,156 ft) and Tibherine 3,887 m (12,753 ft) 3) West-North-West Ridge (ONO Arete). (First ascent by J de Lepinay and party, 1936). Infrequently climbed, but

5621-404: 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

5698-431: Was 25 years of age and organized the murder expedition with two accomplices, Younes Ouaziyad (27) and Rachid Afatti (33) who filmed the murders. A fourth suspect, Abderrahim Khayali, had his sentence elevated from life imprisonment to the death penalty. Khayali was part of the expedition into the mountain, but left the group before the killings. The court upheld received sentences from 5 to 30 years in prison for nineteen of

5775-484: Was formed. According to a researcher at the Danish Institute for International Studies , "Moroccan authorities appear to have a good grip on the jihadist situation, and cooperate with European and US authorities". Moroccans are overrepresented in " diaspora terrorism", which is terrorism which takes place outside the borders of Morocco; for example, two Moroccans were behind the 2017 London Bridge attack ,

5852-559: Was held in her native town of Ikast , Denmark on 12 January. The Prime Minister of Denmark , Lars Løkke Rasmussen , attended the funeral. Ueland was buried on 21 January in Jæren , Norway. The Norwegian Minister of Health, Bent Høie , and the Moroccan Ambassador , Lamia Radi, attended the ceremony. In Morocco, news of the attack was met with widespread outrage and condemnation. The incident received extensive coverage in

5929-422: Was quickly apprehended following the incident, after police found an ID in the victims' tent, that had been left behind by the suspect. Three additional suspects, Abdessamad Ejjoud, Rachid Afatti, and Younes Ouaziyad, were later apprehended by the police while riding a bus during the morning rush hour in the nearby city of Marrakesh . The three suspects were caught in possession of bladed weapons. Abdessamad Ejjoud

#50949