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Two alluvial terraces and the present flood plain were studied at two locations along the Susquehanna and Unadilla Rivers in south-central New York state. They have formed since deglaciation and incision of the stream channels into the valley train deposits. The higher terrace has noncumulative soil profiles with well-developed color B horizons predominantly of silt loam and very fine sandy loam. The terrace is weathered to a degree similar to nearby glacial outwash terraces that have caps of similarly textured sediments. Incision that produced the terrace occurred before 9705 ± 130 yr B.P. The lower terrace is characterized by relatively thick, vertical-accretion deposits of silt loam that contain sequences of thin, buried A, color B, and C horizons. They were formed between about 3240 ± 110 (14C data of soil humin) and 235 ± 80 yr B.P. Deposits above the 235 ± 80 yr B.P. stratum are unweathered. The soil stratigraphy and 14C dates of soil humin from buried A horizons are surprisingly well correlated between sites. Most sediments of the present flood plain have been deposited since 1120 ± 80 yr B.P. Incipient A horizons and oxidation of inherited organic matter in the subsoil are the only evidence of pedogenesis in the flood-plain deposits that are older than 275 ± 80 yr B.P. The most recent flood-plain fill deposited since then is unaltered. These youngest sediments of the flood plain along with the youngest veneer of vertical-accretion deposits on the lowest terrace are associated with an increased rate of deposition largely attributable to clearing of the forests by settlers, beginning in the late 1700s. Comparison of the alluvial stratigraphy with the radiocarbon-dated pollen stratigraphy of southwestern New York (Miller 1973) reveals some apparent time correlations between alluvial events and vegetation changes. This gives reason to speculate that climatic change or forest catastrophes such as disease or drought are causes of some of the alluvial events. 相似文献
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Implications of ozone depletion for surface-water photochemistry: Sensitivity of clear lakes 总被引：1，自引：0，他引：1
Norman M. Scully Warwick F. Vincent David R. S. Lean William J. Cooper 《Aquatic Sciences - Research Across Boundaries》1997,59(3):260-274
Increased ultraviolet-B radiation (UV-B) in aquatic ecosystems brought about by stratospheric ozone depletion may result in
increased formation rates of photochemical reaction products in the surface waters of aquatic ecosystems. In this study, the
potential impact of increases in lower wave-length radiation on the formation of hydrogen peroxide (H2O2) and singlet oxygen (1O2) was modelled for lakes over a range of dissolved organic carbon (DOC) concentrations. The impact of increased UV-B radiation
on the production of carbon monoxide (CO) was also calculated for two humic stained systems. The relative increases of H2O2 and1O2 production were greater in the clear lakes (70% increase in photochemical reaction rates near the surface) than the coloured
systems (25%). Production of CO in the study sites also increased under depleted ozone conditions implying increased DOC losses
to the overlying atmosphere. 相似文献
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A. Maimun A. Priyanto A.H. Muhammad C.C. Scully Z.I. Awal 《Ocean Engineering》2011,38(11-12):1291-1299
This paper presents an experimental investigation on the manoeuvring characteristics of a pusher-barge system for deep (H/d>3) and shallow water (H/d=1.3) condition. Since, the operation of pusher-barge mainly concentrates on confined waters, there is a need to predict and analyze the manoeuvring characteristic of the system for a safe and acceptable performance. A time domain simulation programme was developed for this purpose. A series of model experiments were carried out to determine the hydrodynamic coefficients using a planar motion mechanism (PMM). The time domain simulation shows the manoeuvring characteristic in the form of turning circle trajectories and zig-zag manoeuvre based on the hydrodynamic coefficients, which were derived based on experimental results. The manoeuvring characteristics in shallow and deep water conditions were compared through the simulation results. A comparison of simulation results based on experimental and empirical driven coefficients for both conditions shows that the experimental coefficients gave better manoeuvring characteristics for both turning circle trajectories and zig-zag manoeuvre. 相似文献
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Aisling Gallagher 《New Zealand geographer》2017,73(1):15-24
There has been a significant growth in childcare in New Zealand (NZ) since 2006. Shaped by debates around the marketisation of childcare, this paper will make some key observations about the NZ childcare market. I will argue that the landscape of childcare has changed in favour of a burgeoning private sector and consider the recent impetus for corporatisation. Finally, I will examine the discourse of parental ‘choice’ which pervades policy discussions around ECE in New Zealand and how this plays out in the face of an expanding private for‐profit sector. 相似文献
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High‐quality 3D seismic data are used to investigate the effect of the Parihaka Fault on the geometry of submarine channels in Northern Graben of the Taranaki Basin, New Zealand. The Parihaka Fault comprises of four segments (S1–S4) with variable displacements. As part of the Plio‐Pleistocene Giant Foresets Formation, the older Channel Complex Systems 1 and 2 reveal a two‐stage evolution: (a) a syn‐tectonic depositional stage with channels incising the slope during early fault growth (ca. 4.5 Ma) and (b) a stage of sediment bypass (ca. 3 Ma) leading to the infill of hanging‐wall depocentres. The Channel Complex System 3 is syn‐tectonic relative to segment S3 and was formed at ca. 2.5 Ma. We show that the successive generation of new fault segments towards the north controlled the formation of depocentres in the study area. This occurred in association to rotation and uplift of the footwall block of the Parihaka Fault and subsidence of its hanging‐wall block, with fault activity controlling the orientation of channel systems. As a result, we observe three drainage types in the study area: oblique, transverse and parallel to the Parihaka Fault. This work is important as it shows that relay zones separating the Parihaka Fault segments had limited influence on the geometry and location of channel systems. Submarine channels were diverted from their original courses close to the Parihaka Fault and flowed transversally to fault segments instead of running through relay ramps, contrasting to what is often recorded in the literature. A plausible explanation for such a discrepancy relates to rapid progradation of the Giant Foresets Formation during the Plio‐Pleistocene, with channel complexes becoming less confined, favouring footwall incision and basinward deposition of submarine fans. 相似文献
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Murtagh A 《Irish geography : bulletin of the Geographical Society of Ireland》2010,43(2):149-159
Getting food to our plates has become a highly complex, industrialised and globalised process. However, transformations in how our food is supplied are not without resistance. Initiatives are emerging that take a step back to simpler, alternative methods of food supply, bringing the producer and consumer closer together. Alternative food initiatives which are commonly found in Ireland include allotments, community gardens, farmers' markets, farm shops and on-farm food enterprises. Understanding alternative food activities as a social movement can illuminate a fresh perspective on their nature and potential. While briefly considering the broad dynamics of alternative food activity in Ireland, this exploratory paper looks at the question of the nature of resistance and whether a collective vision may exist across initiatives, illustrated by two examples, a community garden and consumer food co-op. Finally some conclusions as to how alternative food initiatives may play a transformative role within the contemporary food system are discussed. 相似文献
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Bumjoon Kang Jason Y. Scully Orion Stewart Philip M. Hurvitz Anne V. Moudon 《International journal of geographical information science》2013,27(3):440-453
Sidewalk geodata are essential to understand walking behavior. However, such geodata are scarce, only available at the local jurisdiction and not at the regional level. If they exist, the data are stored in geometric representational formats without network characteristics such as sidewalk connectivity and completeness. This article presents the Split-Match-Aggregate (SMA) algorithm, which automatically conflates sidewalk information from secondary geometric sidewalk data to existing street network data. The algorithm uses three parameters to determine geometric relationships between sidewalk and street segments: the distance between streets and sidewalk segments; the angle between sidewalk and street segments; and the difference between the lengths of matched sidewalk and street segments. The SMA algorithm was applied in urban King County, WA, to 13 jurisdictions’ secondary sidewalk geodata. Parameter values were determined based on agreement rates between results obtained from 72 pre-specified parameter combinations and those of a trained geographic information systems (GIS) analyst using a randomly selected 5% of the 79,928 street segments as a parameter-development sample. The algorithm performed best when the distances between sidewalk and street segments were 12 m or less, their angles were 25° or less, and the tolerance was set to 18 m, showing an excellent agreement rate of 96.5%. The SMA algorithm was applied to classify sidewalks in the entire study area and it successfully updated sidewalk coverage information on the existing regional-level street network data. The algorithm can be applied for conflating attributes between associated, but geometrically misaligned line data sets in GIS. 相似文献
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Vishnu Reddy Lucille Le Corre David P. O’Brien Andreas Nathues Edward A. Cloutis Daniel D. Durda William F. Bottke Megha U. Bhatt David Nesvorny Debra Buczkowski Jennifer E.C. Scully Elizabeth M. Palmer Holger Sierks Paul J. Mann Kris J. Becker Andrew W. Beck David Mittlefehldt Jian-Yang Li David Blewett 《Icarus》2012,221(2):544-559
NASA’s Dawn spacecraft observations of Asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 μm filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1–6 vol.%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ～400 km Veneneia basin by a low-velocity (<2 km/s) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System. 相似文献