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Fluvial depositional landforms
Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019
Richard J. Chorley, Stanley A. Schumm, David E. Sugden
River terraces may occasionally be produced by the incision of bedrock surfaces but they are most usually the remnants of floodplains which have been trenched by rivers. Terraces border most valleys, and where the valley has been filled with alluvium, it is logical to assume that buried terraces lie beneath the floor of the valley in a wide variety of possible configurations (Figure 14.17). Floodplain trenching is produced either by negative baselevel movements (see Chapter 2) or by complex climatic changes leading to the provision of less sediment or more water. The former causes produce headward surges of rejuvenation leading to composite polycyclic stream segments, graded to different baselevels, separated by nickpoints and correlated downstream with river terrace remnants which may be paired on opposite sides of the valley (Figure 14.18A). Of course, these polycyclic terraces are commonly complicated by the occurrence of subsidiary terraces caused by the complex response of drainage basins to renewed erosion referred to earlier. Other non-cyclic terraces can be produced by a variety of mechanisms and, for example, unpaired terraces can be generated by the slow lowering of a broad floodplain by a widely swinging meander belt which produces terrace remnants which converge downstream (Figure 14. 18B), rather than being more or less parallel as in the case of polycyclic terraces. In reality, most rivers have complex terrace sequences, as well as nickpoints resulting from polycyclic, geological, tributary entrance, or changed bedload/discharge causes.
Cameron Highlands Hydroelectric Scheme: Landuse Change — Impacts and Issues
Published in Bjørn Honningsvåg, Grethe Holm Midttømme, Kjell Repp, Kjetil Arne Vaskinn, Trond Westeren, Hydropower in the New Millennium, 2020
The massif area has developed physiographically as a separate unit lying high above the country to east and west of it, and it has experienced its own isolated cycles of erosion, deposition, rejuvenation, river capture and so forth. The upper reaches of the Sg. Telom and Sg. Bertam lie within the Cameron Highlands massif and exhibit unusual physiographic characteristics. The valley walls are steep and are benched by river terraces that occur at levels ranging from a few meters to several hundred meters above the present riverbeds. Such valleys are especially well developed in the valleys of the Sg. Telom (four distinct terraces at heights of 1158.5 m, 1181.4 m, 1105.2 m and, 1272.9 m) and its tributaries near Kuala Terla and the Sg. Bertam near Tanah Rata.
Occurrence and enrichment sources of cobalt, chromium, and nickel in soils of Mitrovica Region, Republic of Kosovo
Published in Journal of Environmental Science and Health, Part A, 2021
Milihate Aliu, Robert Šajn, Trajče Stafilov
The investigated area belongs to the Vardar Zone. The geotectonic unit is covered by metamorphic, sedimentary and magmatic rocks of the younger Paleozoic and Triassic ages, the Cretaceous flysch, the Miocene volcanic rocks with pyroclastites as well as younger Pliocene and Quaternary sediments. The younger Paleozoic consists of green schists, shales, marbles, quartzite and metamorphosed basic magmatic rocks successively alternate to the lover part of series, while the upper one is built up of limestones (Stan Tёrg), riche by lead-zinc mineralization (Trepça mine). The overlying Mesozoic rocks consist of lower Triassic metaconglomerates and metasandstones. The middle Triassic is represented by metamorphosed volcanogenic-sedimentary formation (shales schists, metasandstones, metadiabase) and serpentinite (northern part of investigated area). Upper Triassic rocks are represented by the Cretaceous limestones (western part of investigated area) and flysch formations (alevrolites, shales and sandstones with olistolites). The Tertiary formation is represented with the Lower Miocene conglomerate, sandstone and clay and Miocene latite, quartz-latite and their pyroclastites (north-eastern part of investigated area). The Quaternary is represented by Pleistocene fluvio-lacustrine sediments, gravel and sand deposits, river terraces and alluvium (central and southern-east part of investigated area).[14]
Investigation of tunnel movement of the Thameslink tunnels below site S3 of King’s cross zone development
Published in Geomechanics and Geoengineering, 2020
Oli O’Shea, Chrysothemis Paraskevopoulou, Richard Miller
The London Basin, basin is the phrase used when describing the sedimentary geology of London (Sheppard 1917) with outcropping Chalk in the North and South forming the original limits of the basin (Royse et al. 2012). The basin itself represents a shallow, generally east-west synclinal fold, formed during the Variscan Orogeny roughly 290 Ma. A Palaeozoic basement has been established at ~300 m beneath London during oil and gas exploration drilling (Sumbler 1996) that has been overlain by a widespread layer of Gault which is topped by a ~ 200 m thick group of Chalk, (Figure 4). Above the Chalk are the later marine deposits that begin with the fine-grained sand with clay called the Thanet Sands at the base of the succession. The Lambeth Group succession follows, consisting of clay mottled with fine-grained sand and flint pebble beds, which then grade into the Harwich Formation as the lower Member of the Thames Group. In this group is the Claygate Member with interbedded sand with clay at the top, the London Clay Member, the focus of this paper, with clay and silt, fine sand clay at the base and the Bagshot Formation at the surface. In areas of central London, these Palaeogene deposits are overlain by river terraces formed by the River Thames.
Geochemical characteristics of soil of the city of Skopje, Republic of Macedonia
Published in Journal of Environmental Science and Health, Part A, 2019
Trajče Stafilov, Robert Šajn, Laura Ahmeti
A geological map of the investigated area was prepared according to the Geological Map of the Republic of Macedonia from 1977 (Figure 3).[15] It can be seen Quaternary floodplain sediments, Quaternary swamp sediments and Quaternary younger river terraces are present along the Vardar, Treska and Lepenec rivers. The mountain Vodno in the south is built mostly of Pliocene sediments and Paleozoic rocks, with some Miocene sediments and Quaternary older river terraces at the foot of the mountain close to the city. Pliocene and Miocene sediments compose the western part of the study area, while the northern part is mostly composed of Quaternary older river terraces and Miocene sediments. Quaternary swamp sediments are present in the eastern part of the study area.