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1
Arbogast, Alan F., e William C. Johnson. "Climatic Implications of the Late Quaternary Alluvial Record of a Small Drainage Basin in the Central Great Plains". Quaternary Research 41, n. 3 (maggio 1994): 298–305. http://dx.doi.org/10.1006/qres.1994.1034.
Testo completoAbstract (sommario):
AbstractFour late-Quaternary alluvial fills and terraces are recognized in Wolf Creek basin, a small (163 km2) drainage in the Kansas River system of the central Great Plains. Two terraces were created during the late Pleistocene: the T-4 is a fill-top terrace underlain by sand and gravel fill (Fill I), and the T-3 is a strath terrace cut on the Cretaceous Dakota Sandstone. Both Fill II (early Holocene) and Fill III (late Holocene) are exposed beneath the T-2, a Holocene fill-top terrace. The T-1 complex, consisting of one cut and three fill-top terraces, is underlain by Fills III and IV. A poorly developed floodplain (T-0) has formed within the past 1000 yr. As valleys in Wolf Creek basin filled during the early Holocene, an interval of soil formation occurred about 6800 yr B.P. Early Holocene fill has been found only in the basin's upper reaches, indicating that extensive erosion during the middle Holocene removed most early-Holocene fill from the middle and lower reaches of the basin. Valley filling between 5000 and 1000 yr B.P. was interrupted by soil formation about 1800, 1500, and 1200 yr B.P. As much as 6 m of entrenchment has occurred in the past 1000 yr. Holocene events in Wolf Creek basin correlate well with those in other localities in the central Great Plains, indicating that widespread changes in climate, along with adjustments driven by complex response, influenced fluvial activity.
2
Arauza, Hanna M., Alexander R. Simms, Leland C. Bement, Brian J. Carter, Travis Conley, Ammanuel Woldergauy, William C. Johnson e Priyank Jaiswal. "Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change". Quaternary Research 85, n. 1 (gennaio 2016): 118–32. http://dx.doi.org/10.1016/j.yqres.2015.11.006.
Testo completoAbstract (sommario):
Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.
3
Schirmer, Wolfgang. "Edifice of Fluvial Terrace Flights, Stacks and Rows". Geosciences 10, n. 12 (15 dicembre 2020): 501. http://dx.doi.org/10.3390/geosciences10120501.
Testo completoAbstract (sommario):
The paper presents a review of the architecture and structures of river deposits in valleys. A new terminology for some features is included in this review. It presents principles of the fluvial systems with morphological river terraces and fluments (new term for terrace bodies), different stages of the morphological terraces, the texture—the arrangement—of fluments in the form of terrace flights, terrace stacks and terrace rows, and the (inner) structure of a single flument. The contact between the valley fill and the bedrock is named by the new term “pelma”. Special topics deal with flument overlaps and insight into the deepest valley fill down to the bedrock. A comparison with other terms of the fluvial inventory is annexed.
4
Tofelde, Stefanie, Sara Savi, Andrew D. Wickert, Aaron Bufe e Taylor F. Schildgen. "Alluvial channel response to environmental perturbations: fill-terrace formation and sediment-signal disruption". Earth Surface Dynamics 7, n. 2 (1 luglio 2019): 609–31. http://dx.doi.org/10.5194/esurf-7-609-2019.
Testo completoAbstract (sommario):
Abstract. The sensitivity of fluvial systems to tectonic and climatic boundary conditions allows us to use the geomorphic and stratigraphic records as quantitative archives of past climatic and tectonic conditions. Thus, fluvial terraces that form on alluvial fans and floodplains as well as the rate of sediment export to oceanic and continental basins are commonly used to reconstruct paleoenvironments. However, we currently lack a systematic and quantitative understanding of the transient evolution of fluvial systems and their associated sediment storage and release in response to changes in base level, water input, and sediment input. Such knowledge is necessary to quantify past environmental change from terrace records or sedimentary deposits and to disentangle the multiple possible causes for terrace formation and sediment deposition. Here, we use a set of seven physical experiments to explore terrace formation and sediment export from a single, braided channel that is perturbed by changes in upstream water discharge or sediment supply, or through downstream base-level fall. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace cutting, and (3) the transient response of sediment export from the basin. In general, an increase in water discharge leads to near-instantaneous channel incision across the entire fluvial system and consequent local terrace cutting, thus preserving the initial channel slope on terrace surfaces, and it also produces a transient increase in sediment export from the system. In contrast, a decreased upstream sediment-supply rate may result in longer lag times before terrace cutting, leading to terrace slopes that differ from the initial channel slope, and also lagged responses in sediment export. Finally, downstream base-level fall triggers the upstream propagation of a diffuse knickzone, forming terraces with upstream-decreasing ages. The slope of terraces triggered by base-level fall mimics that of the newly adjusted active channel, whereas slopes of terraces triggered by a decrease in upstream sediment discharge or an increase in upstream water discharge are steeper compared to the new equilibrium channel. By combining fill-terrace records with constraints on sediment export, we can distinguish among environmental perturbations that would otherwise remain unresolved when using just one of these records.
5
Norton, K. P., F. Schlunegger e C. Litty. "On the potential for regolith control of fluvial terrace formation in semi-arid escarpments". Earth Surface Dynamics 4, n. 1 (2 febbraio 2016): 147–57. http://dx.doi.org/10.5194/esurf-4-147-2016.
Testo completoAbstract (sommario):
Abstract. Cut–fill terraces occur throughout the western Andes, where they have been associated with pluvial episodes on the Altiplano. The mechanism relating increased rainfall to sedimentation is, however, not well understood. Here, we apply a hillslope sediment model and reported cosmogenic nuclide concentrations in terraces to examine terrace formation in semi-arid escarpment environments. We focus on the Pisco river system in western Peru in order to determine probable hillslope processes and sediment transport conditions during phases of terrace formation. Specifically, we model steady-state and transient hillslope responses to increased precipitation rates. The measured terrace distribution and sediment agree with the transient predictions, suggesting strong climatic control on the cut–fill sequences in western Peru primarily through large variations in sediment load. Our model suggests that the ultimate control for these terraces is the availability of sediment on the hillslopes, with hillslope stripping supplying large sediment loads early in wet periods. At the Pisco river, this is manifest as an approximately 4-fold increase in erosion rates during pluvial periods. We suggest that this mechanism may also control terrace occurrence other semi-arid escarpment settings.
6
Norton, K. P., F. Schlunegger e C. Litty. "On the potential for regolith control of fluvial terrace formation in semi-arid escarpments". Earth Surface Dynamics Discussions 3, n. 3 (20 agosto 2015): 715–38. http://dx.doi.org/10.5194/esurfd-3-715-2015.
Testo completoAbstract (sommario):
Abstract. Cut-fill terraces occur throughout the western Andes where they have been associated with pluvial episodes on the Altiplano. The mechanism relating increased rainfall to sedimentation is however not well understood. Here, we apply a hillslope sediment model and reported cosmogenic nuclide concentrations in terraces to examine terrace formation in semi-arid escarpment environments. We focus on the Rio Pisco system in western Peru in order to determine probable hillslope processes and sediment transport conditions during phases of terrace formation. Specifically, we model steady state and transient hillslope responses to increased precipitation rates. The measured terrace distribution and reconstructed sediment loads measured for the Rio Pisco agree with the transient model predictions, suggesting strong climatic control on the cut-fill sequences in western Peru primarily through large variations in sediment load. Our model suggests that the ultimate control for these terraces is the availability of sediment on the hillslopes with hillslope stripping supplying large sediment loads early in wet periods. At the Rio Pisco, this is manifest as an approximately 4 × increase in erosion rates during pluvial periods. We suggest that this mechanism may also control terrace occurrence in other semi-arid escarpment settings.
7
Zhang, Jia-Fu, Wei-Li Qiu, Gang Hu e Li-Ping Zhou. "Determining the Age of Terrace Formation Using Luminescence Dating—A Case of the Yellow River Terraces in the Baode Area, China". Methods and Protocols 3, n. 1 (20 febbraio 2020): 17. http://dx.doi.org/10.3390/mps3010017.
Testo completoAbstract (sommario):
Dating fluvial terraces has long been a challenge for geologists and geomorphologists, because terrace straths and treads are not usually directly dated. In this study, the formation ages of the Yellow River terraces in the Baode area in China were determined by dating fluvial deposits overlying bedrock straths using optically stimulated luminescence (OSL) dating techniques. Seven terraces (from the lowest terrace T1 to the highest terrace T7) in the study area were recognized, and they are characterized by thick fluvial terrace deposits overlaid by loess sediments. Twenty-five samples from nine terrace sections were dated to about 2–200 ka. The OSL ages (120–190 ka) of the fluvial samples from higher terraces (T3–T6) seem to be reliable based on their luminescence properties and stratigraphic consistency, but the geomorphologic and stratigraphic evidence show that these ages should be underestimated, because they are generally similar to those of the samples from the lower terrace (T2). The formation ages of the terrace straths and treads for the T1 terrace were deduced to be about 44 ka and 36 ka, respectively, based on the deposition rates of the fluvial terrace deposits, and the T2 terrace has the same strath and tread formation age of about 135 ka. The incision rate was calculated to be about 0.35 mm/ka for the past 135 ka, and the uplift rate pattern suggests that the Ordos Plateau behaves as a rigid block. Based on our previous investigations on the Yellow River terraces and the results in this study, we consider that the formation ages of terrace straths and treads calculated using deposition rates of terrace fluvial sediments can overcome problems associated with age underestimation or overestimation of strath or fill terraces based on the single age of one fluvial terrace sample. The implication is that, for accurate dating of terrace formation, terrace sections should be systematically sampled and dated.
8
Sion, Brad D., Fred M. Phillips, Gary J. Axen, J. Bruce J. Harrison, David W. Love e Matthew J. Zimmerer. "Chronology of terraces in the Rio Grande rift, Socorro basin, New Mexico: Implications for terrace formation". Geosphere 16, n. 6 (6 ottobre 2020): 1457–78. http://dx.doi.org/10.1130/ges02220.1.
Testo completoAbstract (sommario):
Abstract The Rio Grande rift hosts a remarkable record of Quaternary river incision preserved in an alluvial terrace sequence that has been studied for more than a century. However, our understanding of Rio Grande incision history in central New Mexico since the end of basin filling ca. 0.78 Ma remains hampered by poor age control. Robust correlations among Rio Grande terrace sequences in central and southern New Mexico are lacking, making it difficult to address important process-related questions about terrace formation in continental-scale river systems. We present new age controls using a combination of 40Ar/39Ar, 36Cl surface-exposure, and 14C dating techniques from alluvial deposits in the central New Mexico Socorro area to document the late Quaternary incision history of the Rio Grande. These new age controls (1) provide constraints to establish a firm foundation for Socorro basin terrace stratigraphy, (2) allow terrace correlations within the rift basin, and (3) enable testing of alternative models of terrace formation. We identified and mapped a high geomorphic surface interpreted to represent the end of basin filling in the Socorro area and five distinct, post–Santa Fe Group (ca. 0.78 Ma) alloformations and associated geomorphic surfaces using photogrammetric methods, soil characterization, and stratigraphic descriptions. Terrace deposits exhibit tread heights up to 70 m above the valley floor and are 5 to >30 m thick. Their fills generally have pebble-to-cobble bases overlain by fine-to-pebbly sand and local thin silt and clay tops. Alluvial-fan terraces and associated geomorphic surfaces grade to former valley levels defined by axial terrace treads. Carbon-14 ages from detrital charcoal above and below a buried tributary terrace tread show that the most recent aggradation event persisted until ca. 3 ka during the transition from glacial to modern climate conditions. Drill-log data show widespread valley fill ∼30 m thick that began aggrading after glacial retreat in northern New Mexico and southern Colorado (ca. 14 ka). Aggradation during this transition was likely due to hillslope destabilization, increased sediment yield, decreased runoff, and reduced stream competence. Chlorine-36 ages imply similar controls on earlier terraces that have surface ages of ca. 27–29, 64–70, and 135 ka, and suggest net incision during glacial expansions when increased runoff favored down-cutting and bedload mobilization. Our terrace chronology supports existing climate-response models of arid environments and links tributary responses to the axial Rio Grande system throughout the central Rio Grande rift. The terrace chronology also reflects a transition from modest (60 m/m.y.) to rapid (300 m/m.y.) incision between 610 and 135 ka, similar to patterns observed throughout the Rio Grande rift and the western United States in general.
9
Layzell, Anthony L., e Rolfe D. Mandel. "Late Quaternary landscape evolution and bioclimatic change in the central Great Plains, USA". GSA Bulletin 132, n. 11-12 (10 aprile 2020): 2553–71. http://dx.doi.org/10.1130/b35462.1.
Testo completoAbstract (sommario):
Abstract A systematic study of floodplains, terraces, and alluvial fans in the Republican River valley of south-central Nebraska provided a well-dated, detailed reconstruction of late Quaternary landscape evolution and resolved outstanding issues related to previously proposed Holocene terrace sequences. Stable carbon isotope (δ13C) values determined on soil organic matter from buried soils in alluvial landforms were used to reconstruct the structure of vegetation communities and provided a means to investigate the relationships between bioclimatic change and fluvial activity for the period of record. Our study serves as a model for geomorphological and geoarcheological investigations in stream valleys throughout the central Great Plains and wherever loess-derived late Quaternary alluvial fans occur, in particular. Holocene alluvial landforms in the river valley include a broad floodplain complex (T-0a, T-0b, and T-0c), a single alluvial terrace (T-1), and alluvial fans that mostly grade to the T-1 (AF-1) and T-0c (AF-0c) surfaces. Remnants of a late Pleistocene terrace (T-2), mantled by Holocene (Bignell) loess, are also preserved, and some Holocene alluvial fans (AF-2) grade to T-2 surfaces. Radiocarbon ages suggest that the T-1 fill and AF-1 fans aggraded between ca. 9000–1000 yr B.P. Hence, nearly all of the Holocene alluvium in the river valley is stored in these landforms. Sedimentation, however, was interrupted by several periods of landscape stability and soil formation. Radiocarbon ages from the upper A horizons of buried soils in the T-1 and AF-1 fills, indicating approximate burial ages, cluster at ca. 6500, 4500, 3500, and 1000 yr B.P. Also, based on the radiocarbon ages, the T-0c fill and AF-0c fans were aggrading between ca. 2000–900 yr B.P. Given that the T-0c fill and upper parts of the T-1 fill were both aggrading after ca. 2000 yr B.P., we suggest that the T-1 surface was abandoned between ca. 4500–3500 yr B.P., but subsequent aggradation of both the T-1 and T-0c fills occurred due to large-magnitude flood events during the late Holocene. The δ13C data indicate a shift from ∼40% C4 biomass at ca. 6000 to ∼85% at ca. 4500 yr B.P. We propose a scenario where (1) a reduction in C3 vegetation after 6000 yr B.P. destabilized the uplands, resulting in an increase in sediment supply and aggradation of the T-1 fill and AF-1 fans, and (2) the establishment of C4 vegetation by ca. 4500 yr B.P. stabilized the uplands, resulting in a reduction in sediment supply and subsequent incision and abandonment of the T-1 and most AF-1 surfaces. The proposed timing and nature of landscape and bioclimatic change are consistent with regional records from the central Great Plains.
10
Srivastava, Pradeep, Jayant K. Tripathi, R. Islam e Manoj K. Jaiswal. "Fashion and phases of late Pleistocene aggradation and incision in the Alaknanda River Valley, western Himalaya, India". Quaternary Research 70, n. 1 (luglio 2008): 68–80. http://dx.doi.org/10.1016/j.yqres.2008.03.009.
Testo completoAbstract (sommario):
AbstractWe study the aggradation and incision of the Alaknanda River Valley during the late Pleistocene and Holocene. The morphostratigraphy in the river valley at Deoprayag shows the active riverbed, a cut terrace, and a fill terrace. The sedimentary fabric of the fill terrace comprises four lithofacies representing 1) riverbed accretion, 2) locally derived debris fan, 3) the deposits of waning floods and 4) palaeoflood records. The sedimentation style, coupled with geochemical analysis and Optically Stimulated Luminescence (OSL) dating, indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21–18 ka and 13–9 ka. During these periods, sediment supply was relatively higher. Incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient. The cut terrace formed at ~ 5 ka during a phase of stable climate and tectonic quiescence. The palaeoflood records suggest wetter climate 200–300 yr ago when the floods originated in the upper catchment of the Higher Himalaya and in the relatively drier climate ~ 1.2 ka when locally derived sediments from the Lesser Himalaya dominated flood deposits. Maximum and minimum limits of bedrock incision rate at Deoprayag are 2.3 mm/a and 1.4 mm/a.
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Matsu'ura, Tabito, Akira Furusawa e Hidetaka Saomoto. "Long-term and short-term vertical velocity profiles across the forearc in the NE Japan subduction zone". Quaternary Research 71, n. 2 (marzo 2009): 227–38. http://dx.doi.org/10.1016/j.yqres.2008.12.005.
Testo completoAbstract (sommario):
AbstractWe estimated the long-term vertical velocity profile across the northeastern Japan forearc by using the height distribution of late Quaternary marine and fluvial terraces, and we correlated the ages of the two marine terraces with marine isotope stages (MIS) 5.5 and 5.3 or 5.1 by cryptotephra stratigraphy. The uplift rate, estimated as 0.11–0.19 m ka− 1 from the relative heights between the terrace surfaces and eustatic sea levels, was nearly equal to, or slightly slower than, the uplift rate farther inland (0.15–0.19 m ka− 1), as determined from the relative heights of fill terrace surfaces. In contrast, the short-term vertical velocity profile, obtained from GPS observations, showed that the forearc is currently subsiding at a maximum rate of 5.4 ± 0.4 mm yr− 1. Thus, the current short-term (geodetic) subsidence does not reflect long-term (geological) tectonic movement. Short-term vertical deformation is probably driven by subduction erosion or elastic deformation caused by interplate coupling, or both. However, long-term uplift is probably due not to moment release on the mega-thrust but to crustal thickening.
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Catling, H. W. "A Late Bronze Age House- or Sanctuary-model from The Menelaion, Sparta". Annual of the British School at Athens 84 (novembre 1989): 171–75. http://dx.doi.org/10.1017/s0068245400020906.
Testo completo
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Mizutani, Takeshi. "Laboratory experiment and digital simulation of multiple fill-cut terrace formation". Geomorphology 24, n. 4 (settembre 1998): 353–61. http://dx.doi.org/10.1016/s0169-555x(98)00027-0.
Testo completo
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Yatsyshyn, Andriy, e Piotr Gębica. "STUDY OF THE HOLOCENE STAGE OF FORMATION OF THE DNIESTER VALLEY IN THE EASTERN CARPATHIAN FORELAND". PROBLEMS OF GEOMORPHOLOGY AND PALEOGEOGRAPHY OF THE UKRANIAN CARPATHIANS AND ADJACENT AREAS, n. 11(01) (dicembre 2020): 118–39. http://dx.doi.org/10.30970/gpc.2020.1.3204.
Testo completoAbstract (sommario):
The article describes the main stages of studying of the floodplain and the first floodplain terrace of the Dniester river within the Eastern Carpathian Foreland fragment of the valley, and evaluates the results of existing studies. It is discovered that during all the stages of the research morphological and morphometric parameters of the floodplain and the first floodplain terrace of the Dniester river, morphology and facie structures of the alluvial accumulations, as well as palynological analyses of biogenic accumulations buried in an alluvial series are performed. The results obtained during the palynological analyzes are used to date the erosion-accumulation cycles and to reconstruct the physical-geographical conditions of the time of the floodplain and the first floodplain formation of the Dniester terrace. The radiocarbon dating of biogenic sediments buried in alluvial series is also actively conducted at the last stage of the research. The array of geological and geomorphological information collected at the first two stages of research made it possible to establish that, first, the first floodplain terrace and floodplain were formed during the Holocene in the Dniester Valley. The first floodplain terrace (the height of which reaches 4–6 m above the Dniester riverbed) can be considered as a high floodplain which is often covered by high floods. The terrace is accumulative, but unlike all other terraces of the Dniester it is devoid of the loess cover. In the cross-sections of its accumulations the deposits of the alluvium of the channel facies builted of pebbles are exposed and covered with the alluvium of the floodplain facies composed of sands, sandy loams and loams. The total thickness of alluvium reaches 9–10 m and it doesn’t varysignificantly downstream of the Dniester. Except the Upper Dniester basin, where the thickness of the alluvium increases to 10–18 m, and the layers of peat are found. The floodplain is 4–5 m above the Dniester riverbed and is built of alluvium of the channel facies, dominated by sand and pebble series. In someplaces floodplain is covered with sandy or loamy deposits of floodplain facies. Secondly, in the Eastern Carpathian Foreland part of the Dniester valley the course of fluvial morpholitogenetic processes was regulated not only by climatic changes and neotectonic movements, but also by human economic activity. During the XIX–XX centuries especially large-scale human influence was on the Dniester riverbeds by construction of flood ramparts, reclamation canals, etc. The results of recent geomorphological research conducted within the studied fragment of the river valley particularly palynological and radiocarbon dating have significantly improved the idea of morphology, structure and history of floodplain formation and the first floodplain terrace of the Dniester. The research revealed that the accumulation of alluvium of the first floodplain terrace which is above the Dniester riverbed reaches 5,5–6,5 (7) m and started to develop in the late Pleistocene (Bølling–Allerød interstadial) (13 000–11 000 years ago (GI–1)). Presumably in the early Dryas (11 000–10 000 years ago (GS–1)), the first floodplain terrace was dissected by the meandering channel of the Dniester. The alluvial deposits that fill these large paleomeanders are still well preserved and are often exposed in the ledges of the first terrace. The further development of the floodplain and first floodplain terrace of the Dniester river was taking place in several stages such as the end of the boreal, the beginning of the atlantic, the end of the atlantic, subboreal, the beginning of the subatlantic, as well as during V–VI, X–XII and XIV–XVI centuries. These stages are identified in correlation with the cycles of humidification of the climate and the growth of fluvial activity of riverbeds (flood phases). As a result of the intensification of erosion-accumulation activity of the Dniester the two – three levels of Holocene floodplain were formed up to 4–5 m and 3–4 m high. The first traces of human activity within the studied fragment of the Dniester valley were dated by subboreal and recorded by the presence of grain pollen in the spore-pollen diagrams of Mainych (Upper Dniester Basin) and Tsvitova (Galician-Bukachiv Basin) sections. Key words: Dniester valley; floodplain; the first floodplain terrace; alluvium; phases of floods; Allerød; early Dryas; Holocene.
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Gutiérrez, Francisco, Mario Zarroca, Carmen Castañeda, Domingo Carbonel, Jesús Guerrero, Rogelio Linares, Carles Roqué e Pedro Lucha. "Paleoflood records from sinkholes using an example from the Ebro River floodplain, northeastern Spain". Quaternary Research 88, n. 1 (5 giugno 2017): 71–88. http://dx.doi.org/10.1017/qua.2017.23.
Testo completoAbstract (sommario):
AbstractThis work introduces for the first time the concept of using sinkholes in fluvial valleys as recorders of past floods. The notion is illustrated through the investigation of a complex sinkhole located in a broad floodplain underlain by salt-bearing Cenozoic evaporites. This active sinkhole comprises a large subsidence depression affecting the floodplain and the edge of a terrace, and a nested collapse sinkhole that used to host a sinkhole pond. A borehole drilled in the buried sinkhole pond revealed an ~7.8-m-thick fill that records around 2700 yr of clayey lacustrine deposition interrupted by three types of detrital facies. Two thick pebble gravel beds have been attributed to major high-competence floods: a paleoflood that occurred in Visigothic times (1537–1311 cal yr BP) and the 1961 Great Ebro River Flood, which is the largest event of the instrumental record. A trench dug in the portion of the terrace affected by subsidence exposed a mid-Holocene slack-water paleoflood deposit. The disadvantages and advantages of sinkholes as archives of past flood histories are discussed.
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Woolfe, Ken J., e Richard G. Purdon. "Deposits of a rapidly eroding meandering river: Terrace cut and fill in the Taupo Volcanic Zone". New Zealand Journal of Geology and Geophysics 39, n. 2 (giugno 1996): 243–49. http://dx.doi.org/10.1080/00288306.1996.9514708.
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Baskin, Jon A. "Early Pliocene horses from late Pleistocene fluvial deposits, Gulf Coastal Plain, south Texas". Journal of Paleontology 65, n. 6 (novembre 1991): 995–1006. http://dx.doi.org/10.1017/s0022336000033308.
Testo completoAbstract (sommario):
Isolated teeth and post-cranial elements of fossil vertebrates were recovered from sand and gravel pits in valley fill and terrace deposits along the Nueces River in San Patricio and Nueces Counties, Texas. A log from the valley fill deposit has been radiocarbon dated at 13,230 ± 110 BP. The fauna is mixed and comprises typical late Pleistocene taxa and relatively abundant remains of early Pliocene (latest Hemphillian) horses. The latter group includes Astrohippus albidens (Mooser), Nannippus spp., Neohipparion eurystyle (Cope), and a derived species of either Calippus or Pseudhipparion. Many of these specimens show little or no evidence of abrasion, in spite of the fact that they may have been transported at least 12–25 km. The source beds for these early Pliocene horses are unknown, but the fossils were probably eroded from older, updip sediments of the upper Goliad Formation during a low stand of sea level at the end of the Pleistocene and deposited during the late Wisconsinan.
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McIlwraith, Thomas. "Digging Out and Filling In". Articles 20, n. 1 (1 agosto 2013): 15–33. http://dx.doi.org/10.7202/1017560ar.
Testo completoAbstract (sommario):
A half-million square metres (50 hectares) was brought in to railroad and commercial use at wharfage-level along the Toronto lakefront during the 1850s. This major engineering project involved cutting down the terrace south of Front Street, and this was the source of most of the fill dumped into the Bay. Neither railroad cars nor harbour dredges were capable of delivering the additional material necessary for building anticipated port lands, and many parts of the waterfront remained improperly filled for decades. The land-area that was created should be regarded as a byproduct of short-run, selfish commercial interests, abetted by a City Council that gave only lip-service to the concept of a parklike lakefront.
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Tofelde, Stefanie, Taylor F. Schildgen, Sara Savi, Heiko Pingel, Andrew D. Wickert, Bodo Bookhagen, Hella Wittmann, Ricardo N. Alonso, John Cottle e Manfred R. Strecker. "100 kyr fluvial cut-and-fill terrace cycles since the Middle Pleistocene in the southern Central Andes, NW Argentina". Earth and Planetary Science Letters 473 (settembre 2017): 141–53. http://dx.doi.org/10.1016/j.epsl.2017.06.001.
Testo completo
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Taillefer, François. "La morphologie des environs de Québec et la basse-vallée du Saint-Laurent". Cahiers de géographie du Québec 2, n. 4 (12 aprile 2005): 177–91. http://dx.doi.org/10.7202/020087ar.
Testo completoAbstract (sommario):
The morphology of the Québec region and the lower St. Lawrence valley is reappraised in this article divided in three parts. The physical landscape is described in part I ; the structural conditions are examined in part II and the morphological problems are presented in part III. The relief is the result of a succession of glacial episodes and submersion and emersion episodes which followed glaciation. The over deepening of the Limoilou depression and the opening of Calvaire lake and Cap Rouge depressions are the results of the glacier. To the submerged phase correspond the alluvial fill, especially thick in the Limoilou depression, and during the emersion phase, the St. Lawrence cut in soft schists the Ancienne Lorette and the lower terrace which would have been shaped after the over deepening of the Limoilou depression.
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Toonen, Willem H. J., Michiel M. de Molenaar, Frans P. M. Bunnik e Hans Middelkoop. "Middle Holocene palaeoflood extremes of the Lower Rhine". Hydrology Research 44, n. 2 (12 novembre 2012): 248–63. http://dx.doi.org/10.2166/nh.2012.162.
Testo completoAbstract (sommario):
A Chézy-based hydraulic model was run to estimate the magnitude of extreme floods of Middle Holocene age in the Lower Rhine Valley (Germany). Input parameters were gathered from the field and literature, and used in ten scenarios to calculate a best guess estimate for the minimum size of extreme floods. These events have been registered as slackwater deposits on elevated terrace levels and in a palaeochannel fill. The modelled minimum discharge is 13,250 m3 sec−1 for a Middle Holocene flood with an estimated recurrence interval between 1,250 and 2,500 years. A sensitivity analysis on different input parameters enables evaluation of factors which cause the relatively large range in modelled discharges. Understanding the origin of uncertainties in modelled discharges is important for making geologically based calculations of palaeoflood magnitudes important in modern flood frequency analyses, which generally lack information on the magnitudes of rare events.
22
Harrison, D. J., C. Laban, J. O. Leth e B. Larsen. "Sources of sand and gravel on the Northern European Continental Shelf". Geological Society, London, Engineering Geology Special Publications 13, n. 1 (1998): 3–13. http://dx.doi.org/10.1144/gsl.eng.1998.013.01.01.
Testo completoAbstract (sommario):
AbstractThe extraction of marine sand and gravel has taken place in a number of countries around the North Sea, the Baltic Sea and English Channel for several centuries, but large-scale dredging for aggregates only began in earnest in the 1960s. Today, marine sands and gravels have an increasing role to play in maintaining European supplies of concreting aggregates as well as material for beach nourishment and constructional fill. The distribution of sand and gravel resources offshore is uneven. They vary in their thickness, their composition and grading, and their proximity to the shore. Many deposits lie in places that are currently inaccessible to the dredging industry.This paper outlines the production of marine sand and gravel in northern Europe and describes the distribution, composition and Quaternary origins of the most important marine sand and gravel resources in northern Europe. Examples are given for the UK, the Netherlands and Denmark, and in summary form for France, Belgium, Norway, Sweden, Ireland and Germany. Most marine sand and gravel deposits are of fluvial or glacial origin and have been reworked to varying degrees by marine and coastal hydrodynamic processes. They represent a range of former depositional environments, including fluvial channel-fill or terrace deposits, glacial meltwater plain deposits, seabed lag gravels and degraded shingle beach or spit deposits, as well as modern marine tidal sandbanks and sandwave deposits.
23
Karyati, Karyati, Sri Sarminah, Karmini Karmini, Ali Muhammad Akbar e Rifaldi Hermansyah. "Conservation and economic aspects of a combination of forestry-agricultural crops (Neolamarckia cadamba-Phaseolus vulgaris) and terrace systems in different slope classes". SAINS TANAH - Journal of Soil Science and Agroclimatology 18, n. 1 (30 giugno 2021): 98. http://dx.doi.org/10.20961/stjssa.v18i1.47708.
Testo completoAbstract (sommario):
The utilization of steep lands by planting forestry and agricultural species can provide benefits from soil-water conservation and economic aspects. The combination of planting <em>Neolamarckia cadamba-Phaseolus vulgaris</em> and terrace systems can increase land use values, such as soil conservation, crop production, and farmers’ income. The aim of this study was to analyze silvicultural, hydro-orological, and economic aspects of a combination of forestry-agricultural crops<em> </em>(<em>N. cadamba – P. vulgaris</em>) and terrace systems on two slope classes. Two study plots were established on a steep gradient (25–40%) and a very steep gradient (>40%). The results showed an annual increase in the average diameter and height of <em>N. cadamba</em> of 1.78 cm and 1.84 m, respectively on the steep slope, and 1.68 cm and 1.53 m, respectively on the very steep slope. The surface run off and erosion rate were lower on the steep ground compared to the very steep ground. Erosion hazard indices and levels on the plots in the steep slope and very steep slope were categorized as low and very low; meanwhile the erosion hazard class was I. The profit of <em>P. vulgaris cultivation </em>was IDR 9,360,000.00 ha<sup>–1</sup> per cropping season<sup> </sup>on steep slope and IDR 6,480,000.00 ha<sup>–1</sup> per cropping season on very steep slope. The planting of <em>P. vulgaris</em> as an intercropping plant to fill empty land in between <em>N. cadamba</em> can increase the economic value obtained from selling <em>P. vulgaris</em> in the short term until the leaves of the <em>N. cadamba</em> plant are linked. The combination of planting <em>N. cadamba–P. vulgaris</em> and terrace system on steep slopes is therefore more profitable not only from the economic perspective, but also in lowering runoff and potential erosion rates than on very steep lands.
24
Dingwall, Kirsty, Julie Lochrie e Scott Timpany. "Mount or motte? Recent excavations at Montfode, Ardrossan". Scottish Archaeological Journal 32, n. 2 (ottobre 2010): 121–35. http://dx.doi.org/10.3366/saj.2010.0013.
Testo completoAbstract (sommario):
Montfode Mount near Ardrossan is a monument with an ambiguous interpretation which has been subject to much discussion over the years. The site is a low mound at the end of a broad plateau of flat ground on a raised beach terrace. Recent housing development offered another opportunity to examine the monument's ditches and surroundings. The results cast doubt on previous interpretations of the monument as a medieval motte. Several groups of truncated features were identified in the vicinity, with some forming a probable double-ring roundhouse, and all of the dateable features were Bronze Age. Beaker pottery was found in one pit. The plan of the ditches and possible palisades surrounding the mound were more fully revealed. The work disturbed one part of the inner ditch and the dating of material from the primary fill also suggested a prehistoric date. It is concluded that the site bears most resemblance to a defended settlement of the later prehistoric period.
25
Bruni, Elena T., Richard F. Ott, Vincenzo Picotti, Negar Haghipour, Karl W. Wegmann e Sean F. Gallen. "Stochastic alluvial fan and terrace formation triggered by a high-magnitude Holocene landslide in the Klados Gorge, Crete". Earth Surface Dynamics 9, n. 4 (28 luglio 2021): 771–93. http://dx.doi.org/10.5194/esurf-9-771-2021.
Testo completoAbstract (sommario):
Abstract. Alluvial fan and terrace formation is traditionally interpreted as a fluvial system response to Quaternary climate oscillations under the backdrop of slow and steady tectonic activity. However, several recent studies challenge this conventional wisdom, showing that such landforms can evolve rapidly as a geomorphic system responds to catastrophic and stochastic events, like large-magnitude mass wasting. Here, we contribute to this topic through a detailed field, geochronological, and numerical modelling investigation of thick (>50 m) alluvial sequences in the Klados catchment in southwestern Crete, Greece. The Klados River catchment lies in a Mediterranean climate, is largely floored by carbonate bedrock, and is characterised by well-preserved alluvial terraces and inset fans at the river mouth that exceed the volumes of alluvial deposits in neighbouring catchments of similar size. Previous studies interpreted the genesis and evolution of these deposits to result from a combination of Pleistocene sea-level variation and the region's long-term tectonic activity. We show that the >20 m thick lower fan unit, previously thought to be late Pleistocene in age, unconformably buries a paleoshoreline uplifted in the first centuries CE, placing the depositional age of this unit firmly in the late Holocene. The depositional timing is supported by seven new radiocarbon dates that indicate middle to late Holocene ages for the entire fan and terrace sequence. Furthermore, we report new evidence of a previously unidentified valley-filling landslide deposit that is locally 100 m above the modern stream elevation, and based on cross-cutting relationships, it predates the alluvial sequence. Observations indicate the highly erodible landslide deposit as the source of the alluvial fill sediment. We identify the likely landslide detachment area as a large rockfall scar at the steepened head of the catchment. A landslide volume of 9.08×107 m3 is estimated based on volume reconstructions of the mapped landslide deposit and the inferred scar location. We utilise landslide runout modelling to validate the hypothesis that a high-magnitude rockfall would pulverise and send material downstream, filling the valley up to ∼100 m. This partial liquefaction is required for the rockfall to form a landslide body of the extent observed in the valley and is consistent with the sedimentological characteristics of the landslide deposit. Based on the new age control and the identification of the landslide deposit, we hypothesise that the rapid post-landslide aggradation and incision cycles of the alluvial deposits are not linked to long-term tectonic uplift or climate variations but rather stochastic events such as mobilisation of sediment in large earthquakes, storm events, or ephemeral blockage in the valley's narrow reaches. The Klados case study represents a model environment for how stochastically driven events can mimic climate-induced sedimentary archives and lead to deposition of thick alluvial sequences within hundreds to thousands of years, and it illustrates the ultrasensitivity of mountainous catchments to external perturbations after catastrophic events.
26
Kováč, Michal, Jozef Hók, Jozef Minár, Rastislav Vojtko, Miroslav Bielik, Radovan Pipík, Miloš Rakús, Ján Kráľ, Martin Šujan e Silvia Králiková. "Neogene and Quaternary development of the Turiec Basin and landscape in its catchment: a tentative mass balance model". Geologica Carpathica 62, n. 4 (1 agosto 2011): 361–79. http://dx.doi.org/10.2478/v10096-011-0027-6.
Testo completoAbstract (sommario):
Neogene and Quaternary development of the Turiec Basin and landscape in its catchment: a tentative mass balance modelThe development of the Turiec Basin and landscape evolution in its catchment has been reconstructed by methods of geological research (structural geology, sedimentology, paleoecology, and geochronological data) as well as by geophysics and geomorphology. The basin and its surrounding mountains were a subject of a mass balance study during periods of tectonic activity, accompanied by considerable altitudinal differentiation of relief and also during quiet periods, characterized by a development of planation surfaces in the mountains. The coarse clastic alluvial fans deposited beneath the offshore pelitic sediments document the rapid Middle Miocene uplift of mountains on the margin of the Turiec Basin. The Late Miocene finegrained sedimentation represents the main fill of this basin and its origin was associated with the formation of planation surfaces in the surrounding mountains. The rapid uplift of the western and northern parts of the catchment area during the latest Miocene and Early Pliocene times further generated the deposition of coarse-grained alluvial fans. The Late Pliocene basin inversion, due to uplift of the whole Western Carpathians mountain chain, was associated with the formation of the Early Quaternary pediment and ultimately with the formation of the Turiec river terrace systems.
27
Kaszycki, Christine A. "A model for glacial and proglacial sedimentation in the shield terrane of southern Ontario". Canadian Journal of Earth Sciences 24, n. 12 (1 dicembre 1987): 2373–91. http://dx.doi.org/10.1139/e87-223.
Testo completoAbstract (sommario):
Zonal stagnation is an important element in the regional style of deglaciation in areas of moderate bedrock relief (50–150 m), such as the shield terrane of southern Ontario. Bedrock topography played a major role in the stagnation process, as ice blocks were trapped within bedrock basins of all sizes. Stagnation occurred subglacially as the ice sheet thinned and trapped basal ice became increasingly isolated from its source. Sediment–landform relationships support this model. Bedrock lakes are floored by highly faulted laminated sediment, often displaying large ice-block casts. The dominant depositional landforms are ice-contact terraces, which flank valley walls. Sediment forming the terraces is variable, depending upon ice-marginal depositional environment.Models for two depositional systems are developed: (1) localized ice-marginal and subglacial sedimentation in upland terrain, and (2) thick proglacial basin-fill sequences developed in major structural valleys. In upland areas, sediment cover is thin and discontinuous and is composed primarily of complex sediment-flow assemblages. Basal till is rare but occurs as two distinct lithofacies representing (1) meltout from beneath wholly stagnant ice, and (2) deposition by basal melting from thin slabs of stagnant, debris-rich ice lodged beneath an active shear zone. Thick proglacial basin-fill sequences exhibit complex facies relationships. Ice-contact lacustrine terraces comprise fining-upward subaqueous outwash sequences, developed as density underflows were funnelled between rock knobs and blocks of stagnant ice. Kettle lakes developed within large basins where ice blocks persisted for the longest period of time.
28
Puy, Arnald, Andrea L. Balbo e Olaf Bubenzer. "Radiocarbon Dating of Agrarian Terraces by Means of Buried Soils". Radiocarbon 58, n. 2 (19 gennaio 2016): 345–63. http://dx.doi.org/10.1017/rdc.2015.21.
Testo completoAbstract (sommario):
AbstractSoils buried under terrace fills have been widely used to date the construction of ancient agrarian terraces. The reliability of the obtained radiocarbon dates entirely depends on the degree of preservation and isolation of the Ab horizons and on the amount of embedded older carbon. To assess these caveats, we analyzed 14 14C dates (11 on charred material and 3 on the bulk organic fraction) obtained from buried soils under Andalusi terrace fills in Ricote, Spain (AD 711–1492). The preservation of Ab horizons was assessed through bulk analyses [particle size distribution (PSD), carbon analyses, magnetic susceptibility (Mag Sus)] and statistics [Welch’s ANOVA, MANOVA (Wilk’s lambda) and effect size tests]. The effects of older carbon were quantified through the systematic dating of Ab horizons within the earliest terrace cluster of Ricote. Our results show that (1) Ab horizons were not disturbed nor mixed with the terrace fills above; (2) the dates determined from the bulk organic fraction were statistically significantly older than those provided by the charred material, probably due to the higher stability of the microcharcoal fraction; and (3) the earliest dates measured on charcoal clustered reliably around cal AD 989–1210, suggesting that the first Andalusi irrigated terraces of Ricote were built between the end of the 10th and the beginning of the 13th centuries AD.
29
Paudel, Mukunda Raj, e Harutaka Sakai. "Stratigraphy and depositional environment of late Pleistocene Sunakothi Formation in Kathmandu Basin, central Nepal". Journal of Nepal Geological Society 39 (25 settembre 2009): 33–44. http://dx.doi.org/10.3126/jngs.v39i0.31486.
Testo completoAbstract (sommario):
Thick sandy sequences were recognised between the central and southern part of the basin, it was named as the Sunakothi Formation. We designate the type locality of this formation at Sunakothi, a village lying 3.0 km south of Patan. This formation is extensively distributed in the Nakhu, Kodku, and Godavari Kholas ranging in altitude from ca 1420 m in the southern margin to 1300 m in the central part. The average thickness of this formation ranges from 34 to 60 m. The sedimentary strata are gently inclined towards the north. On the basis of geological mapping this formation is located between the muddy part of the Kalimati Formation of the ancient lake and the terrace gravel deposits. It is further divided into the following four parts: (1) muddy rhythmic basal part, (2) sandy lower part, (3) muddy, sandy, and gravelly middle part, and (4) laminated silty upper part. The basal part shows a transition from the lacustrine to fluvial environment in the south and the prodeltaic environment towards the basin centre. Its lower part contains sandy fluvial to lacustrine delta front deposits whereas the middle part comprises sandy bar, muddy floodplain, and gravelly channel-fill deposits. The upper part of this formation is restricted only to the southern end of the basin and shows marginal shallow lacustrine environments. The sedimentological evidence indicates that the Palaeo-Kathmandu Lake was drained out from the south due to tectonic activities as well as late Pleistocene climatic changes.
30
Hatem, Alexandra E., James F. Dolan, Robert W. Zinke, Robert M. Langridge, Christopher P. McGuire, Edward J. Rhodes, Nathan Brown e Russell J. Van Dissen. "Holocene to latest Pleistocene incremental slip rates from the east-central Hope fault (Conway segment) at Hossack Station, Marlborough fault system, South Island, New Zealand: Towards a dated path of earthquake slip along a plate boundary fault". Geosphere 16, n. 6 (27 ottobre 2020): 1558–84. http://dx.doi.org/10.1130/ges02263.1.
Testo completoAbstract (sommario):
Abstract Geomorphic field and aerial lidar mapping, coupled with fault-parallel trenching, reveals four progressive offsets of a stream channel and an older offset of the channel headwaters and associated fill terrace–bedrock contact at Hossack Station along the Conway segment of the Hope fault, the fastest-slipping fault within the Marlborough fault system in northern South Island, New Zealand. Radiocarbon and luminescence dating of aggradational surface deposition and channel initiation and abandonment event horizons yields not only an average dextral rate of ∼15 mm/yr since ca. 14 ka, but also incremental slip rates for five different time periods (spanning hundreds to thousands of years) during Holocene to latest Pleistocene time. These incremental rates vary through time and are, from youngest to oldest: 8.2 +2.7/−1.5 mm/yr averaged since 1.1 ka; 32.7 +∼124.9/−10.1 mm/yr averaged over 1.61–1.0 ka; 19.1 ± 0.8 mm/yr between 5.4 and 1.6 ka; 12.0 ± 0.9 mm/yr between 9.4 and 5.4 ka, and 13.7 +4.0/−3.4 mm/yr from 13.8 to 9.4 ka, with generally faster rates in the mid- to late Holocene relative to slower rates prior to ca. 5.4 ka. The most pronounced variation in rates occurs between the two youngest intervals, which are averaged over shorter time spans (≤1700 yr) than the three older incremental rates (3700–4500 yr). This suggests that the factor of ∼1.5× variations in Hope fault slip rate observed in the three older, longer-duration incremental rates may mask even greater temporal variations in rate over shorter time scales.
31
Mustafa, Hisham Khalil. "An Insight to the Sedimentological Developments of Quaternary Detritus Ring Fluvial Network, Altun Kupri Paleolake, NE IRAQ". Iraqi Geological Journal 54, n. 2B (31 agosto 2021): 122–33. http://dx.doi.org/10.46717/igj.54.2b.11ms-2021-08-31.
Testo completoAbstract (sommario):
During the Quaternary, an active basin in the shape of open lake originated along the Lesser Zab river at Altun Kupri area. The radial complex of fluvial deposit morphologically initiated by the coarse detritus material, that were transported by the Lesser Zab river and other surrounded valleys in a shape of delta towards the proximal part of coastal plain and the fine sediment to the distal part of it. The coarse one prograde along the fine gradually resulting in the accumulation of about 60 m thickness of continuous Pleistocene fluvial succession mostly of coarse grained sediments with minor sand, silt and clay intervals and some tongues and bands of calcareous mud. The bulk of basin fill is made of two depositional systems, the western and southwestern side was filled up by progradation delta systems, but the northern side was gradually filled up by fluvial sediment of Lesser Zab channel. The water impounded in this lake because of Awanah anticline as a ridge in front of the lake which is open with output channel that crosses the shallow gorge and the gorge became deeper and deeper gradually till the water drooped from the lake. There are several possibilities that this ring shape depression of Altun Kupri paleolake generated, first: the depression at Altun Kupri is formed as a result of dissolving lenses of Anhydrite and gypsum of the Fat’ha Formation beneath the northern limb of Awanah Anticline after the collapse of the cavity roof. second: the presence of ring shape cliffs of about 50m thick and depression is bounded by 8km in diameter of cross bedded conglomerates and sandstone and the third: the depression of Altun Kupri paleolake can be developed by meteoritic impact, with several sedimentological and structural evidence such as a delta distributary fan, and there was a hanging terrace at a high level along the gorge
32
Martin, Charles W. "Late Holocene Alluvial Chronology and Climate Change in the Central Great Plains". Quaternary Research 37, n. 3 (maggio 1992): 315–22. http://dx.doi.org/10.1016/0033-5894(92)90069-u.
Testo completoAbstract (sommario):
AbstractAlluvium in one reach of the Republican River valley, south-central Nebraska, dates to the Holocene. Radiocarbon dating of fills underlying the two terraces in the valley reveals that entrenchment between 4500 and 3700 yr B.P. formed the high terrace. Subsequently, alternating aggradation and stability occurred until sometime between 1800 and 1100 yr B.P. Following another period of alluviation, channel incision formed the low terrace. General synchrony between this chronology and other late Holocene fluvial chronologies of the central Great Plains suggests climatic control of fluvial activity. The episodes of incision are tentatively correlated with different climate regimes, illustrating the difficulty of attributing a given fluvial response to a particular direction of climatic change.
33
Panno, Samuel V., B. Brandon Curry, Hong Wang, Keith C. Hackley, Chao-Li Liu, Craig Lundstrom e Juanzuo Zhou. "Climate change in southern Illinois, USA, based on the age and δ13C of organic matter in cave sediments". Quaternary Research 61, n. 3 (maggio 2004): 301–13. http://dx.doi.org/10.1016/j.yqres.2004.01.003.
Testo completoAbstract (sommario):
Matrix-supported diamicton and uniform to laminated, silty, fine-grained sediment deposited from about 42,500 to 27,600 cal yr B.P. under slackwater conditions nearly filled two caves in southwestern Illinois. At some point, most of the sediment was flushed from the caves and from about 22,700 to 4000 cal yr B.P. floods deposited a drape of sandy and silty sediment on remnant slackwater successions, cobbly alluvium, and bedrock (especially from 7700 to 4000 cal yr B.P.). Clay mineral analyses of the slackwater cave sediment reveal a provenance of chiefly Petersburg Silt, a smectite- and illite-rich proglacial lacustrine unit present in the overlying Illinois Episode glacial succession. Today, remnants of the ancient subterranean slackwater deposits nearly fill several secondary passages and in at least two locations, cover a cobble-mantled strath terrace 1.3 to 1.5 m above active stream channels. Slumping and sinkhole formation appear to have been important mechanisms for deposition of the ancient subterranean deposits. Slumping of these surficial deposits and associated vegetation can occur along the flanks of sinkholes (in addition to sinkhole formation) and enter caves; however, the finer organics, some of them comminuted during transport into the caves, become part of the cave alluvium. This finer organic fraction is the modern analog of the humified organic matter disseminated in slackwater sediment dated in this investigation by radiocarbon methods. Twenty-four 14C ages on humified organic matter provide chronologic control. The δ13C values of the organic matter reflect the proportion of C4-type to C3-type vegetation growing in and around swallets and sinkholes at the time of redeposition. Drought-tolerant C4-type vegetation was more prevalent relative to C3-type vegetation from 42,500 to 31,200 cal yr B.P. compared to conditions from 28,800 cal yr B.P. to the present. The δ13C values are consistent with the results from other investigations of speleothems and organic matter from loessial paleosols.
34
Cai, Xiao Guang, Jing Shan Bo, Ka Mai Toshitaka, Fa Wu Wang e Ju Wen Li. "Seismic Damage Investigation of Residential Fill Ground in the Eastern Part of Kyoto Basin". Applied Mechanics and Materials 256-259 (dicembre 2012): 2200–2206. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2200.
Testo completoAbstract (sommario):
Several earthquakes record that the residential fills always suffer severe damages. In order to know the seismic damage mechanism and evaluate the damage extent of residential fill ground, research is carried out on two fill grounds in the eastern part of Kyoto basin. The research includes field survey about terrain condition, geological condition, development history, disaster condition during 1995 Kobe earthquake and surface wave explorations. Some remarkable conclusions are summarized as follows: In Jyodo-ji area, it is a residential fill on soft alluvium ground. The geological condition is back swamp. The thickness of surface fill soil is about 1~4 meters. In Kiyomizu-dera area, it is a valley filled ground. The geological condition is hilly platform.
35
Struik, L. C., P. Schiarizza, M. J. Orchard, F. Cordey, H. Sano, D. G. MacIntyre, H. Lapierre e M. Tardy. "Imbricate architecture of the upper Paleozoic to Jurassic oceanic Cache Creek Terrane, central British Columbia". Canadian Journal of Earth Sciences 38, n. 4 (1 aprile 2001): 495–514. http://dx.doi.org/10.1139/e00-117.
Testo completoAbstract (sommario):
Upper Paleozoic to Lower Jurassic oceanic rocks of the Cache Creek Terrane near Fort St. James, in central British Columbia, form a stack of thrust sheets cut by steeply dipping strike-slip faults. Paleontologically dated upper Paleozoic strata include bioclastic shallow-water limestone and ribbon chert. Isotopically dated Permian rocks consist of tonalite sills and stocks and rhyolite flows intercalated with basalt flows. Paleontologically dated lower Mesozoic rocks include greywacke, sandstone, siltstone, argillite, ribbon chert, conglomerate, limestone, and basalt tuff. Trembleur Ultramafite unit of the Cache Creek Complex, in places part of an ophiolite suite, forms thrust sheets and klippen that overlie lower Mesozoic sedimentary rocks. Sedimentological, lithochemical, paleontological, petrological, and textural comparisons with other areas and established models demonstrate that Cache Creek Terrane is an accretionary complex, a structurally stacked assemblage of rocks that originated in diverse and disparate oceanic paleoenvironments. These environments include spreading ridge, oceanic plateau, atoll, trench fill, and possibly arc. Internal imbrication of the terrane is as young as Early Jurassic, as determined from fossil evidence, and the minimum age of obduction of the thrust stack westward onto Stikine Terrane is Middle Jurassic, as determined from dating of a crosscutting pluton. Triassic blueschist and eclogite of Cache Creek Terrane are interpreted to have been primarily uplifted to upper crustal levels during Triassic subduction. Cache Creek Terrane, as a remnant of that subduction process, and caught in the collision between Stikine and Quesnel terranes, marks the position of a lithosphere-scale suture zone, the Pinchi Suture.
36
Lewin, John, Mark G. Macklin e Jamie C. Woodward. "Late Quaternary Fluvial Sedimentation in the Voidomatis Basin, Epirus, Northwest Greece". Quaternary Research 35, n. 1 (gennaio 1991): 103–15. http://dx.doi.org/10.1016/0033-5894(91)90098-p.
Testo completoAbstract (sommario):
AbstractDetailed morpho- and lithostratigraphic investigations, allied with radiometric dating, in the Voidomatis basin, Epirus, northwest Greece, have identified four Quaternary terraced alluvial fills that range from middle Pleistocene to historic in age. Major-periods of alluviation during the late Quaternary were associated with valley glaciation (ca. 26,000–20,000 yr B.P.) and subsequent deglaciation (ca. 20,000–15,000 yr B.P.) in the Pindus Mountains during Late Würmian times, and more recently linked to overgrazing sometime before the 11th century AD. The late Quaternary alluvial stratigraphy of the Voidomatis River is more complex than the “Older Fill” and “Younger Fill” model outlined previously, and it is suggested that these terms should no longer form the basis for defining alluvial stratigraphic units in the Mediterranean Basin.
37
Rius, Gemma, Narcis Mestres, Osamu Eryu e Philippe Godignon. "Tuning the Terrace and Step Stability of 6H-SiC (0001) for Graphene Film Deposition". Materials Science Forum 821-823 (giugno 2015): 953–56. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.953.
Testo completoAbstract (sommario):
Graphene is a 2D material with potential for almost any purpose, thanks to a combination of excellent characteristics, e.g. high electrical conductivity. Graphene grown on SiC wafers is one of the promising routes for graphene integration into planar technology electronic applications. Synthesis is based on the decomposition of a SiC single crystal surface at high temperature, where Si-terminated SiC substrates require the formation of the C buffer layer. In spite of numerous experimental and theoretical works the understanding and control upon crucial factors such as step and terrace stability or surface roughening is far from been fully comprehended and then technologically optimized. We present experimental results on the deposition of graphene onto Si-terminated 6H-SiC. We analyze the effect of ex situ and in situ conditionings of the SiC surface in the thermal decomposition and reconstruction of the SiC terraces, toward higher control upon the growth process of graphene films.
38
Smith, Rhonda J. "(380) The Effect of Kaolin Clay-based Particle Film Applications and Canopy Manipulations on Fruit Composition and Incidence of Cluster Damage due to Sunburn in `Cabernet Sauvignon' Grapevines". HortScience 40, n. 4 (luglio 2005): 1068D—1068. http://dx.doi.org/10.21273/hortsci.40.4.1068d.
Testo completoAbstract (sommario):
The effect of sunlight exposure on yield, fruit composition, amount of damaged clusters, and berry temperature was evaluated in a terraced, hillside `Cabernet Sauvignon' vineyard on the north coast of California. Each terrace contained two vine rows identified as “inside” and “outside” relative to the terrace surface. The standard canopy management practice of removing lateral shoots from below the clusters was imposed with three modifications (“umbrella”, “fogger”, and “umbrella+fogger”) and an unmodified control. Applications of a kaolin-based particle film were made to unmodified canopies and a final treatment consisted of leaving lateral shoots. Canopies with umbrella modifications were not fully vertically shoot positioned. Fogger emitters directed water into the cluster area when ambient temperature reached 33.9 °C beginning in mid-July for a total of 16 fogger-events through 8 Sept. 2004. Treatments were harvested 17 Sept. Yield was affected by row type but not treatment, and inside and outside rows produced an average of 2.1 and 3.4 kg/vine, respectively. Particle film applications significantly reduced berry surface temperatures in the afternoon of two measurement dates by 0.7 and 1.5 °C, respectively. Applications did not significantly affect fruit maturity indices when compared to fruit in the control; however, at the 7% probability level, berry samples from vines that had been treated with kaolin-clay had lower °Brix than samples from control vines. The mean range of sunburn fruit across all treatments was 0.2 to 1.4 clusters per vine. Umbrella and umbrella+fogger treatments significantly reduced the number of damaged clusters (P < 0.05).
39
Cheng, Jian Long, e Hang Fu. "Height Control Measures of Highway Subgrade Fill in Xinjiang Plain Terrain". Applied Mechanics and Materials 368-370 (agosto 2013): 1366–69. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1366.
Testo completoAbstract (sommario):
By analyzing problems of highway subgrade fill height in Xinjiang plain terrain, this paper subdivided plain terrain types and proposed corresponding height control measures of subgrade fill based on features of different subtypes, which provides useful reference to similar engineering in plain terrain.
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Monnier, Gérard. "La file d’attente". Terrain, n. 63 (1 settembre 2014): 72–85. http://dx.doi.org/10.4000/terrain.15503.
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Shtansky, D. V., S. A. Kulinich, K. Terashima, T. Yoshida e Y. Ikuhara. "Crystallography and structural evolution of LiNbO3 and LiNb1−xTaxO3 films on sapphire prepared by high-rate thermal plasma spray chemical vapor deposition". Journal of Materials Research 16, n. 8 (agosto 2001): 2271–79. http://dx.doi.org/10.1557/jmr.2001.0312.
Testo completoAbstract (sommario):
The structure and the crystallography of lithium niobate and lithium niobate–tantalate thin films (0.2–1.0 μm in thickness) with the tantalum composition range of 0 ≤ x ≤ 0.5 grown on (0001) sapphire substrate by thermal plasma spray chemical vapor deposition have been studied by means of cross-sectional high-resolution transmission electron microscopy and x-ray diffraction. The tantalum composition in the films shows a minor effect on the rocking curve full width at half maximum values. The narrowest rocking curve width was obtained for the LiNb0.5Ta0.5O3 film to be as low as 0.25° θ. The films are under compressive strain along the c direction; c- and a-axis lattice parameters are correspondingly smaller and higher than those of the bulk single crystal. Under optimized growth conditions, the LiNbO3 and LiNb1−xTaxO3 films are 97% c-axis oriented. The film out-of-plane orientation changes from the [0001] to the [0112] direction by either decreasing the growth rate or increasing the substrate temperature. Particular attention has been paid to the orientation of individual grains in the partly c-axis-oriented films. The results demonstrate that their orientations are not random and specific orientation relationships are preferred for the film nucleation. The surface of as-received sapphire substrate reveals polishing defects with the well-defined surface ledges of 1–2 nm in height with smooth terraces of 25 nm in width. In the case of columnar growth, the terrace width becomes a limiting factor controlling the lateral crystallite size in the film. Finally, the film growth mechanism is discussed.
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Krakow, William. "The Structure of Thin Gold Films at the Early Stage of Continuous Film Growth". Proceedings, annual meeting, Electron Microscopy Society of America 48, n. 1 (12 agosto 1990): 18–19. http://dx.doi.org/10.1017/s0424820100178847.
Testo completoAbstract (sommario):
The use of a transmission electron microscope to observe surface structure of thin films has been demonstrated in recent years by diffraction contrast imaging to ∼ 10Å resolution using the forbidden reflections of [111] Au and at atomic resolution using bright-field phase contrast on both [001] and [111] oriented Au films. It has also been possible to demonstrate that beyond a minimum thickness, these films can be free standing and viewed in the microscope without significant modification due to the incident electron beam generating sputtering events at high beam currents. It is therefore now possible to obtain free standing [001] Au films which exhibit various types of surface topography. These films were obtained by varying the growth parameters with a microprocessor controller attached to a UHV deposition system. The deposition of Au was precisely controlled onto a thick Ag substrate which was initially deposited upon NaCl single crystals.Fig. 1 shows a low magnification image ∼ 40Å thick [001] Au film grown at a vacuum level of 5 × 10-9 Torr, 50° substrate temperature and a deposition rate of ∼ 1/20 ML/sec. Clearly defined atomic step regions are visible as demonstrated by the terrace-like contrast variations over extended regions i.e. a step-ledge growth regime. Regions between these terrace areas represent coalescence of individual grains which were not attached at an earlier stage of growth. These regions exhibit finer scale terraces and ledges which follow either <100> or <110> directions as evidenced by comparing their directions to stacking faults and twins occasionally observed in the field of view. Small holes are also present which have crystallographic edge facets and anomalous contrast bands also occur which represent the lack of tracking of the upper surface layer growth to steps which exist at the lower surface. Fig. 1 was obtained by diffraction contrast from the direct beam alone. It was not necessary to use the forbidden reflections here since they produced too drastic a contrast change.
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Tornatore, Jean-Louis. "La dette des fils". Terrain, n. 50 (2 marzo 2008): 140–57. http://dx.doi.org/10.4000/terrain.9293.
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Kleinspehn, Karen L. "Cretaceous sedimentation and tectonics, Tyaughton–Methow Basin, southwestern British Columbia". Canadian Journal of Earth Sciences 22, n. 2 (1 febbraio 1985): 154–74. http://dx.doi.org/10.1139/e85-014.
Testo completoAbstract (sommario):
The Mesozoic Tyaughton–Methow Basin straddles the Fraser–Yalakom–Pasayten – Straight Creek (FYPSC) strike-slip fault zone between six tectono-stratigraphic terranes in southwestern British Columbia. Data from Hauterivian–Cenomanian basin fill provide constraints for reconstruction of fault displacement and paleogeography.The Early Cretaceous eastern margin of the basin was a region of uplifted Jurassic plutons and active intermediate volcanism. Detritus shed southwestward from that margin was deposited as the marine Jackass Mountain Group. Albian inner to mid-fan facies of the Jackass Mountain Group can be correlated across the Yalakom Fault, suggesting 150 ± 25 km of post- Albian dextral offset. Deposits of the Jackass Mountain Group overlap the major strike- slip zone (FYPSC). If that zone represents the eastern boundary of the tectono-stratigraphic terrane, Wrangellia, then accretion of Wrangellia to terranes to the east occurred before late Early Cretaceous time.The western margin of the basin first became prominent with Cenomanian uplift of the Coast Mountain suprastructure. Uplift is recorded by dispersal patterns of the volcaniclastic Kingsvale Group southwest of the Yalakom Fault.Reversing 110 km of Late Cretaceous – early Tertiary dextral motion on the Fraser – Straight Creek Fault followed by 150 km of Cenomanian – Turonian motion on the Yalakom – Ross Lake Fault restores the basin to a reasonable depositional configuration.
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Watson, Sybil, Mark G. Macklin e John Lewin. "Terraced fills in the Rheidol Valley, Wales". Journal of Quaternary Science 2, n. 2 (1987): 165–66. http://dx.doi.org/10.1002/jqs.3390020209.
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Gill, David W. J. "The Temple Of Aphaia On Aegina: Further Thoughts On The Date Of The Reconstruction". Annual of the British School at Athens 88 (novembre 1993): 173–81. http://dx.doi.org/10.1017/s0068245400590005.
Testo completoAbstract (sommario):
The publication of further ceramic material from the terrace fills surrounding the temple of Aphaia on Aegina brings into question the present date assigned to the reconstruction by the excavation team. The cumulative effect of black-figured, red-figured, and black-glossed pottery, as well as lamps and amphorae from the terrace fills, seems to indicate that the temple may be later than the Persian wars. Much of the late material finds parallels from contexts in the Athenian Agora which are usually thought, on the conventional chronology, to date from the time of the Persian wars. If the revised views of these contexts are taken into account, then the temple of Aphaia may have to be dated lower still.
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Innes, James, Wishart Mitchell, Charlotte O’Brien, David Roberts, Mairead Rutherford e David Bridgland. "A Detailed Record of Deglacial and Early Post-Glacial Fluvial Evolution: The River Ure in North Yorkshire, UK". Quaternary 4, n. 1 (8 marzo 2021): 9. http://dx.doi.org/10.3390/quat4010009.
Testo completoAbstract (sommario):
The lower reaches of the River Ure, on the flanks of the Pennine Hills in northern England, contain sedimentary and erosional landforms that are a record of fluvial activity during deglaciation and valley-glacier retreat at the end of the last (Devensian) glacial period, and in the subsequent post-glacial Holocene. Terraces and channels, most of which are now relict features well above the altitude of the present river, attest to the impacts of massive meltwater discharge and deposition of sand and gravel outwash, and dynamic river regimes with rapid incision. Through field survey, we have created a detailed geomorphological map of these landforms and glacial and fluvioglacial surface deposits, as well as the terraces and palaeochannels that were abandoned by the river due to avulsion and incision-driven course changes. We have recorded the nature of the outwash gravels, now effectively terrace features, from exposed sections in working quarries, one of which we discuss here. The palaeochannels have accumulated sediment fills and we have examined several which lie within the range of 100 and 16 m above present sea level. The results of lithostratigraphic, palynological, and radiocarbon analyses at two main and three subsidiary sites indicate that palaeochannel ages range from almost 14,000 to approximately 4000 calibrated years ago in a clear altitudinal sequence. The oldest are probably caused by rapid incision due to deglaciation-driven isostatic uplift. The similarity in date of the three downstream sites suggests that a late Holocene combination of climatic deterioration and increased human activity in the catchment caused instability and entrenchment. Pollen data from the channel fills provide relative dating, and agree well with pollen records from other regional Lateglacial and Holocene sites. Non-pollen palynomorph (NPP) analysis at one of the sites allows reconstruction of the hydrological history of channel infill. This research shows that the application of an integrated suite of research techniques can yield a highly detailed understanding of fluvial evolution and landscape history.
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Uchiyama, Hirokazu, Yuko Ogawa, Hiroyuki Kita e Hideki Kuwajima. "Migration test of thin film PZT actuator with terrace structure". Proceedings of the JSME annual meeting 2003.5 (2003): 291–92. http://dx.doi.org/10.1299/jsmemecjo.2003.5.0_291.
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Ramírez Gómez, Carmen. "Crébillon Fils, terra incógnita en el panorama literario francés del siglo XVIII". Philologia Hispalensis 1, n. 7 (1992): 215–26. http://dx.doi.org/10.12795/ph.1992.v07.i01.18.
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Kumar, Anil, e Pradeep Srivastava. "The role of climate and tectonics in aggradation and incision of the Indus River in the Ladakh Himalaya during the late Quaternary". Quaternary Research 87, n. 3 (maggio 2017): 363–85. http://dx.doi.org/10.1017/qua.2017.19.
Testo completoAbstract (sommario):
AbstractThe geomorphic evolution of the upper Indus River that traverses across the southwest (SW) edge of Tibet, and the Ladakh and Zanskar ranges, was examined along a ~350-km-long stretch of its reaches. Based on the longitudinal river profile, stream length gradient index, and river/strath terraces, this stretch of the river is divided into four segments. Valley fill river terraces are ubiquitous, and strath terraces occur in the lower reaches where the Indus River cuts through deformed Indus Molasse. Optically stimulated luminescence ages of river/strath terraces suggest that valley aggradation occurred in three pulses, at ~52, ~28, and ~16 ka, and that these broadly coincide with periods of stronger SW Indian summer monsoon. Reconstructed longitudinal river profiles using strath terraces provide an upper limit on the bedrock and provide incision rates ranging from 1.0±0.3 to 2.2±0.9 mm/a. These results suggested that rapid uplift of the western syntaxes aided by uplift along the local faults led to the formation of strath terraces and increased fluvial incision rates along this stretch of the river.