874 resultados para ridge line


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Urban developments have exerted immense pressure on wetlands. Urban areas are normally centers of commercial activity and continue to attract migrants in large numbers in search of employment from different areas. As a result, habitations keep coming up in the natural areas / flood plains. This is happening in various Indian cities and towns and large habitations are coming up in low-lying areas, often encroaching even over drainage channels. In some cases, houses are constructed even on top of nallahs and drains. In the case of Kochi the situation is even worse as the base of the urban development itself stands on a completely reclaimed island. Also the topography and geology demanded more reclamation of land when the city developed as an agglomerative cluster. Cochin is a coastal settlement interspersed with a large backwater system and fringed on the eastern side by laterite-capped low hills from which a number of streams drain into the backwater system. The ridge line of the eastern low hills provides a welldefined watershed delimiting Cochin basin which help to confine the environmental parameters within a physical limit. This leads to an obvious conclusion that if physiography alone is considered, the western flatland is ideal for urban development. However it will result in serious environmental deterioration, as it comprises mainly of wetland and for availability of land there has to be large scale filling up of these wetlands which includes shallow mangrove-fringed water sheets, paddy fields, Pokkali fields, estuary etc.Chapter 1 School 4 of Environmental Studies The urban boundaries of Cochin are expanding fast with a consequent over-stretching of the existing fabric of basic amenities and services. Urbanisation leads to the transformation of agricultural land into built-up areas with the concomitant problems regarding water supply, drainage, garbage and sewage disposal etc. Many of the environmental problems of Cochin are hydrologic in origin; like water-logging / floods, sedimentation and pollution in the water bodies as well as shoreline erosion

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pdf en couleur au format 119 x 84 cm, échelle 1:10.000 et 1:50.000

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Pdf en couleur au format 252 x 119 cm, échelle 1:20.000

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Pdf en couleur au format 252 x 119 cm, échelle 1:20.000

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Guide et ses annexes à destination des utilisateurs des cartes relatives à la recherche "Cartographie des anciens cours d’eau, lignes de creux et des bassins versants de l'île de Montréal". Aide à la compréhension du contexte, des définitions, de la méthodologie et des hypothèses relatives à la réalisation des documents cartographiques suivants: ■ Carte des anciens cours d'eau de l'île de Montréal, Mahaut V., 2016 ■ Carte des creux et crêtes et des voiries de l'île de Montréal, 1:20.000, Mahaut V., 2016 [http://hdl.handle.net/1866/16313] ■ Carte des creux et crêtes et de l'altimétrie de l'île de Montréal, 1:20.000, Mahaut V.,2016 [http://hdl.handle.net/1866/16312] ■ Recensement cartographique des anciens cours d’eau de l’île de Montréal et tracé des creux et des crêtes, Carte index 1:50.000, Cartes A4, B3, B4, C3, C4, D1, D2, D3, D4, E1, E2, E3, E4, 1:10.000, Mahaut V., 2016 [http://hdl.handle.net/1866/16311]

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Pdf en couleur au format 119 x 84 cm, échelle 1:10.000 et 1:50.000

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Pdf en couleur au format 252 x 119 cm, échelle 1:20.000

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Pdf en couleur au format 252 x 119 cm, échelle 1:20.000

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Guide et ses annexes à destination des utilisateurs des cartes relatives à la recherche "Cartographie des anciens cours d’eau, lignes de creux et des bassins versants de l'île de Montréal". Aide à la compréhension du contexte, des définitions, de la méthodologie et des hypothèses relatives à la réalisation des documents cartographiques suivants: ■ Carte des anciens cours d'eau de l'île de Montréal, Mahaut V., 2016 ■ Carte des creux et crêtes et des voiries de l'île de Montréal, 1:20.000, Mahaut V., 2016 [http://hdl.handle.net/1866/16313] ■ Carte des creux et crêtes et de l'altimétrie de l'île de Montréal, 1:20.000, Mahaut V.,2016 [http://hdl.handle.net/1866/16312] ■ Recensement cartographique des anciens cours d’eau de l’île de Montréal et tracé des creux et des crêtes, Carte index 1:50.000, Cartes A4, B3, B4, C3, C4, D1, D2, D3, D4, E1, E2, E3, E4, 1:10.000, Mahaut V., 2016 [http://hdl.handle.net/1866/16311]

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Sediments recovered from seven Last Glacial Maximum grounding lines sites, around the Antarctic Peninsula, were analyzed using micromorphology. This is the first evidence that grounding line sediments from around the Antarctic Peninsula have complex deformational histories and subglacial origins. It was determined that grounding zone wedge contain multiple units, or diamicton layers, with homogenized boundaries. The multiple diamicton units / layers are due to the accretionary formation of a grounding line wedge. All the sediments were deposited via deformation, and continual reincorporation, homogenization of lower diamicton layers by upper diamicton layers produced what macroscopically appeared to be a single massive diamicton unit. The morainal ridge that was sampled, alternatively, is composed of a single unit, or diamicton layer, that was subglacial in origin and believed to have been pushed out to form a ridge that was subsequently deformed via glacial push.

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Hole 1105A penetrated 158 m of gabbros at a site offset 1.3 km east-northeast from Hole 735B on the Atlantis Bank near the Atlantis II Fracture Zone. A total of 118 m of dominantly medium- to coarse-grained intercalated Fe-Ti oxide gabbro and olivine gabbro was recovered from Hole 1105A that shows many petrographic features similar to those recovered from the upper part of Hole 735B. The main rock types are distinguished based on the constituent cumulus phases, with the most primitive gabbros consisting of olivine, plagioclase, and clinopyroxene. The inferred crystallization order is subsequently Fe-Ti oxides (ilmenite and titanomagnetite), followed by orthopyroxene, then apatite, and finally biotite. Orthopyroxene appears to replace olivine in a narrow middle interval. The magmatic evolution is likewise reflected in the mineral compositions. Plagioclase varies from An66 to An28. Olivine varies from Fo78 to Fo35. The gap in olivine crystallization occurs between Fo46 and Fo40 and coincides approximately with the appearance of orthopyroxene (~En50). The clinopyroxenes show large compositional variation in Mg/(Mg + Fe total) from 0.84 to 0.51. The nonquadrilateral cations of clinopyroxene similarly show large variations with Ti increasing for the olivine gabbros and decreasing for the Fe-Ti oxide gabbros with the decrease in Mg/(Mg + Fe total). The apatites are mainly flourapatites. The compositional variation in the gabbros is interpreted as a comagmatic suite resulting from fractional crystallization. Pyroxene geothermometry suggests equilibration temperatures from 1100°C and below. The coexisting Fe-Ti oxide minerals indicate subsolidus equilibration temperatures from 900°C for olivine gabbros to 700°C for the most evolved apatite-bearing gabbros. The cryptic variation in the olivine gabbros defines two or three lenses, 40 to 60 m thick, each characterized by a distinct convex zoning with a lower segment indicating upward reverse fractionation, a central maximum, and an upper segment showing normal fractionation. The Fe-Ti oxide gabbros show cryptic variations independent of the host olivine gabbros and reveal a systematic upward normal fractionation trend transgressing host olivine gabbro boundaries. Forward fractional crystallization modeling, using a likely parental magma composition from the Atlantis II Fracture Zone (MgO = 7.2 wt%; Mg/[Mg + Fe2+] = 0.62), closely matches the compositions of coexisting olivine, plagioclase, and clinopyroxene. This modeling suggests cosaturation of olivine, plagioclase, and clinopyroxene from 1155°C and the addition of Fe-Ti oxides from 1100°C. The liquid line of descent initially shows increasing FeO with moderately increasing SiO2. After saturation of Fe-Ti oxides, the liquid strongly decreases in FeO and TiO2 and increases in SiO2, reaching dacitic compositions at ~10% liquid remaining. The calculations indicate that formation of olivine gabbros can be accounted for by <65% fractionation and that only the residual 35% liquid was saturated in Fe-Ti oxides. The modeling of the solid fractionation products shows that both the olivine gabbro and the Fe-Ti oxide gabbros contain very small amounts of trapped liquid (<5%). The implications are that the gabbros represent crystal mush that originated in a recharging and tapping subaxial chamber. Compaction and upward melt migration in the crystal mush appear to have been terminated with relatively large amounts of interstitial liquid remaining in the upper parts of the cumulate mush. This termination may have been caused by tectonic disturbances, uplift, and associated withdrawal of magma into the subaxial dike and sill system. Prolonged compaction and cooling of the trapped melt in the mush formed small differentiated bodies and lenses by pressure release migration and crystallization along syntectonic channels. This resulted in differentiation products along lateral and vertical channelways in the host gabbro that vary from olivine gabbro, to Fe-Ti oxide gabbro, gabbronorite, and apatite gabbros and show large compositional variations independent of the host olivine gabbros.

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Glacial landforms in northern Russia, from the Timan Ridge in the west to the east of the Urals, have been mapped by aerial photographs and satellite images supported by field observations. An east-west trending belt of fresh hummock-and-lake glaciokarst landscapes has been traced to the north of 67°N. The southern boundary of these landscapes is called the Markhida Line, which is interpreted as a nearly synchronous limit of the last ice sheet that affected this region. The hummocky landscapes are subdivided into three types according to the stage of postglacial modification: Markhida, Harbei and Halmer. The Halmer landscape on the Uralian piedmont in the east is the freshest, whereas the westernmost Markhida landscape is more eroded. The west- east gradient in morphology is considered to be a result of the time-transgressive melting of stagnant glacier ice and of the underlying permafrost. The pattern of ice-pushed ridges and other directional features reflects a dominant ice flow direction from the Kara Sea shelf. Traces of ice movement from the central Barents Sea are only discernible in the Pechora River left bank area west of 50°E. In the Polar Urals the horseshoe-shaped end moraines at altitudes of up to 560 m a.s.l. reflect ice movement up-valley from the Kara Ice Sheet, indicating the absence of a contemporaneous ice dome in the mountains. The Markhida moraines, superimposed onto the Eemian strata, represent the maximum ice sheet extent in the western part of the Pechora Basin during the Weichselian. The Markhida Line truncates the huge arcs of the Laya-Adzva and Rogovaya ice-pushed ridges protruding to the south. The latter moraines therefore reflect an older ice advance, probably also of Weichselian age. Still farther south, fluvially dissected morainic plateaus without lakes are of pre-Eemian age, because they plunge northwards under marine Eemian sediments. Shorelines of the large ice-dammed Lake Komi, identified between 90 and 110 m a.s.l. in the areas south of the Markhida Line, are radiocarbon dated to be older than 45 ka. The shorelines, incised into the Laya-Adzva moraines, morphologically interfinger with the Markhida moraines, indicating that the last ice advance onto the Russian mainland reached the Markhida Line during the Middle or Early Weichselian, before 45 ka ago.

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The seismic data were acquired north of the Knipovich Ridge on the western Svalbard margin during cruise MSM21/4. They were recorded using a Geometrics GeoEel streamer of either 120 channels (profiles p100-p208) or 88 channels (profiles p300-p805) with a group spacing of 1.56 m and a sampling rate of 2 kHz. A GI-Gun (2×1.7 l) with a main frequency of ~150 Hz was used as a source and operated at a shot interval of 6-8 s. Processing of profiles p100-p208 and p600-p805: Positions for each channel were calculated by backtracking along the profiles from the GI-Gun GPS positions. The shot gathers were analyzed for abnormal amplitudes below the seafloor reflection by comparing neighboring traces in different frequency bands within sliding time windows. To suppress surface-generated water noise, a tau-p filter was applied in the shot gather domain. Common mid-point (CMP) profiles were then generated through crooked-line binning with a CMP spacing of 1.5625 m. A zero-phase band-pass filter with corner frequencies of 60 Hz and 360 Hz was applied to the data. Based on regional velocity information from MCS data [Sarkar, 2012], an interpolated and extrapolated 3D interval velocity model was created below the digitized seafloor reflection of the high-resolution streamer data. This velocity model was used to apply a CMP stack and an amplitude-preserving Kirchhoff post-stack time migration. Processing of profiles p400-p500: Data were sampled at 0.5 ms and sorted into common midpoint (CMP) domain with a bin spacing of 5 m. Normal move out correction was carried out with a velocity of 1500 m s-1 and an Ormsby bandpass filter with corner frequencies at 40, 80, 600 and 1000 Hz was applied. The data were time migrated using the water velocity.

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The zip folder comprises a text file and a gzipped tar archive. 1) The text file contains individual genotype data for 90 SNPs, 9 microsatellites and the mitochondrial ND4 gene that were determined in deep-sea hydrothermal vent mussels from the Mid-Atlantic Ridge (genus Bathymodiolus). Mussel specimens are grouped according to the population (pop)/location from which they have been sampled (first column). The remaining columns contain the respective allele/haplotype codes for the different genetic loci (names in the header line). The data file is in CONVERT format and can be directly transformed into different input files for population genetic statistics. 2) The tar archive contains NetCDF files with larval dispersal probabilities for simulated annual larval releases between 1998 and 2007. For each simulated vent location (Menez Gwen, Lucky Strike, Rainbow, Vent 1-10) two NetCDF files are given, one for an assumed pelagic larval duration of 1 year and the other one for an assumed pelagic larval duration of 6 months (6m).