Evolution of the Western Amazon Lowland Relief: impact of Andean foreland dynamics

The congruency in the depositional origin and age of the uppermost sedimentary strata forming non-flooded rainforest ground (terra firme) in the western and central Amazon lowlands is a much debated subject. Here we conclude from the study of remote sensing imagery that active Andean foreland dynamics have played a major role in the evolution of the Plio-Pleistocene fluvial landscape in the western Amazon. Foreland dynamics have resulted in a terra firme composed of late Tertiary alluvium and younger alluvial terraces and plains. In Peru, thermoluminescence and ¹⁴C dating show local aggradation of this younger alluvium between 180 and 30 ka. The documented high age heterogeneity of the terra firme has implications for considerations of the biogeography of the Amazon forest.     

Scaling variables and interpretation of eigenvalues in principal component analysis of geologic data

The dominant feature distinguishing one method of principal components analysis from another is the manner in which the original data are transformed prior to the other computations. The only other distinguishing feature of any importance is whether the eigenvectors of the inner product-moment of the transformed data matrix are taken directly as the Q-mode scores or scaled by the square roots of their associated eigenvalues and called the R-mode loadings. If the eigenvectors are extracted from the product-moment correlation matrix, the variables, in effect, were transformed by column standardization (zero means and unit variances), and the sum of the p-largest eigenvalues divided by the sum of all the eigenvalues indicates the degree to which a model containing pcomponents will account for the total variance in the original data. However, if the data were transformed in any manner other than column standardization, the eigenvalues cannot be used in this manner, but can only be used to determine the degree to which the model will account for the transformed data. Regardless of the type of principal components analysis that is performed—even whether it is Ror Q-mode—the goodness-of-fit of the model to the original data is given better by the eigenvalues of the correlation matrix than by those of the matrix that was actually factored.     

En echelon crack-arrays in potash salt rock

Summary There are two types of fracture patterns in the yield pillars of the potash mines of Saskatchewan. The individual members of both patterns are tensile (extension) fractures that propagate parallel with the maximum principal stress trajectory (perpendicular to the minimum principal stress). The difference between the two patterns lies in the arrangement of the member fractures. In theen echelon tensile crack-array, the macroscopic fracture consists of individual tensile cracks that are slightly offset from each other. They have only a small overlap and the child crack seems to form randomly on either side of its parent. Consequently, the en echelon tensile crack-array inherits the axial orientation of its members. In contrast, the tensile cracks of anen echelon shear crack-array, have a larger overlap and their lateral displacement from each other is biased in one direction. Therefore, the crack-array is no longer axial but inclined 20–25 degrees from the maximum principal stress direction. With increasing stress, the shear crack-array often collapses, forming theenvelope orhourglass structures of the potash mines.     

Amazon Fan biomarker evidence against the Pleistocene rainforest refuge hypothesis?

Ocean Drilling Program Leg 155 Site 942 on the Amazon Fan is an ideal location for monitoring palaeoclimatic changes within a significant proportion of the Amazon Basin. We present n‐alkane δ¹³C and taraxerol and laevoglucosan concentration records from this site covering the last 38 ka. The entire n‐alkane δ¹³C record is constrained between ?31‰ and ?34‰, which is well within the isotopic range occupied by C₃ vegetation. The concentration and relative abundance of taraxerol, a mangrove indicator, varies by over an order of magnitude, but seems to have had no effect on the n‐alkane δ¹³C record. The laevoglucosan concentrations are extremely low during the last glacial period, suggesting a relatively low occurrence of forest fires. Laevoglucosan concentrations are highest between 13.5 and 12.5 ka, suggesting an increased incidence of Amazon forest fires at the very end of the Younger Dryas. These records, combined with previously published pollen records from Site 932, reveal no evidence for massive incursions of grasslands into Amazonia during the last glacial period, despite evidence of reduced outflow of the Amazon River indicating more arid conditions. We therefore suggest that savannah encroachment, as proposed by the Pleistocene refuge hypothesis, can be refuted as an explanation for high species endemism within the Amazon Basin, and alternative explanations are required. Copyright © 2012 John Wiley & Sons, Ltd.     

Suspended sediment dynamics in the Amazon River of Peru

The erosion and transport of sediments allow us to understand many activities of significance, such as crust evolution, climate change, uplift rates, continental processes, the biogeochemical cycling of pollutants and nutrients. The Amazon basin of Peru has contrasting physiographic and climatic characteristics between the Andean piedmont and the plains and between the north and south of the basin which is why there are 8 gauging stations located along the principal rivers of the Andean piedmont (Marañón, Huallaga, Ucayali) and the plain (Marañón, Tigre, Napo, Ucayali and Amazon rivers). Since 2003, the ORE-Hybam (IRD-SENAMHI-UNALM) observatory has performed out regular measurements at strategic points of the Amazon basin to understand and model the systems, behavior and long-term dynamics. On the Andean piedmont, the suspended yields are governed by a simple model with a relationship between the river discharge and the sediment concentration. In the plain, the dilution effect of the concentrations can create hysteresis in this relationship on a monthly basis. The Amazon basin of Peru has a sediment yield of 541 *10⁶ t year⁻¹, 70% comes from the southern basin.     

Experimental research on the effect of slope morphology on bank collapse in mountain reservoir

Farmers along the Amazon River each year face multiple natural hazards that threaten crop production and limit the potential for agricultural development of the expansive floodplain and active channel. In this paper we report the findings of a study of natural hazard-related risk associated with rice production on silt bars in the active channel of the Amazon River near Iquitos, Peru. Data were gathered in four rice producing communities in 2014 using household surveys (n = 83 households), focus group discussions, surveying of land elevations along the Amazon River, and interpretation of remote sensing imagery. The probability, extent, and severity of rice crop shortfalls were estimated for recent production years and the economic losses to farming households were also assessed. Our findings point to a very high risk of crop shortfalls due to natural hazards, suggesting that a good year brings rice farmers bounty and a bad year, near penury. River stage reversals (repiquetes) and edaphic conditions were found to be more problematic than the often cited hazard of high and/or early floods. Also surprisingly, farmers’ perceptions of hazards and risk diverged markedly from actual shortfalls experienced during the production years studied. Our results provide the first quantitative estimates of risk due to the multiple natural hazards along the Amazon River and point to the need to assist lowland farmers with risk mitigation so as to unlock the considerable potential of Amazon floodlands for agricultural production.     

River tributaries as sediment sinks: Processes operating where the Tapajós and Xingu rivers meet the Amazon tidal river

The Amazon River is the largest fluvial source of fresh water and sediment to the global ocean and has the longest tidally influenced reach in the world. Two major rivers, the Tapajós and Xingu, enter the Amazon along its tidal reach. However, unlike most fluvial confluences, these are not one‐way conduits through which water and sediment flow downstream towards the sea. The drowned‐river valleys (rias) at the confluences of the Tapajós and Xingu with the Amazon River experience water‐level fluctuations associated not only with the seasonal rise and fall of the river network, but also with semidiurnal tides that propagate as far as 800 km up the Amazon River. Superimposed seasonal and tidal forcing, distinct sediment and temperature signatures of Amazon and tributary waters, and antecedent geomorphology combine to create mainstem–tributary confluences that act as sediment traps rather than sources of sediment. Hydrodynamic measurements are combined with data from sediment cores to determine the distribution of tributary‐derived and Amazon‐derived sediment within the ria basins, characterize the sediment‐transport mechanisms within the confluence areas and estimate rates of sediment accumulation within both rias. The Tapajós and Xingu ria basins trap the majority of the sediment carried by the tributaries themselves in addition to ca 20 Mt year^?1 of sediment sourced from the Amazon River. These findings have implications for the interpretation of stratigraphy associated with incised‐valley systems, such as those that dominated the transfer of sediment to the oceans during lowstands in sea level.     

Comparison of automatic classification methods applied to lake geochemical samples

Geochemical samples from part of Lake Geneva were analyzed for 29oxides and trace elements. The variables and samples were subjected to R- and Q-mode analyses. The following techniques were applied in sequence: data transformation (normalization and standardization), data reduction (principal component and factor analysis), and automatic classification (dendrograph). The data were treated using various combinations of these techniques, and the resulting classifications evaluated by means of several criteria. The best classification of the samples is given by a cluster analysis performed on four principal components computed from standardized variables. The discriminatory power of the variables also was measured and determined to depend on their degree of intercorrelation. As a final result, the 29original variables were reduced to four components and the sediment samples classified into four facies, leading to easily interpretable geochemical maps.     

Analysis of compressible axially loaded piles in rock

Analytical solutions are developed for the prediction of the load–settlement response of a compressible axially loaded cast in situ pile in rock. The principal input parameters are derived from the τ–z curve which applies to the contact zone between the pile shaft and the embedment material. For larger diameter piles in rock, these τ–z curves can differ markedly from curves that apply to piles in clay and may include a significant strain hardening region prior to reaching peak strength. In addition to the complete analyses which would normally require the use of a computer, simplified solutions suitable for hand calculations have been derived for the peak load and the pile head displacement to peak. An example of the application of these simplified design calculations is presented.     

Study of horizontal scales of motion observed over Kharagpur during MONTBLEX-1990

Characteristic wavelengths for theu andv components of wind are studied using the Monsoon Trough Boundary Layer Experiment (MONTBLEX) data obtained from a Doppler Sonic Detection and Ranging System (sodar) over the land station Kharagpur (near sea-coast). The principal stability parameter (Z _i/L_o) is used to infer the behaviour of the non-dimensional form of the characteristic wavelength (L _H) within the entire stability range occurring during the sounding periods. This is compared with GATE - 1974 results (over the sea surface) published by Fitzjarrald (1978).     

Estimating the benthic population ofDreissena polymorpha and its impact in the lower Seine River, France

Dreissena larval fluxes were studied in the lower stretch of the Seine River in 1996–1998. Fluxes reached 150×10¹² ind d⁻¹, representing a larval concentration of 5,000 ind l⁻¹ in the Seine estuary. We showed that a sampling frequency with a 3-d interval allowed us to adequately estimate the annual production of larvae. The water residence time in the Seine River and estuary is sufficient for theDreissena larvae to complete their cycle and settlement. High abundance of the larvae in the plankton samples from the Seine River and its estuary showed the existence of a large community of benthic adults, known to be powerful filter-feeders. The progenitor population and the geographical extent of the adultDreissena were estimated from cohort analyses of the planktonic larvae. The maximum density ofDreissena was found in the highly channelized part of the estuary (up to 4,500 ind m⁻²). Estimated values were compared with concentration of mussels in the benthic traps and samples. Calculated filtration rates of benthic mussels were compared with those of larvae at different stages and with filtration of the zooplankton community. The impact of theDreissena was much higher than that of zooplankton; the filtration of the larvae exceeded that of adults during short periods of maximum larval emission.     

The dominance of nucleation: The Jewish experience in the early phase of Jewish settlement

The dominance of the nucleated pattern among Jewish settlement in Palestine is not merely the outcome of central planning. The early colonies, established between 1882 and 1914, were already nucleated, although there was some experimentation with other patterns. The main type of settlement established in this period, with which the present study deals, was themoshava. This freeholder family-farm village was strongly nucleated, and practically all the types which were created after it reveal the impact of its nucleted spatial plan. The attempts to establish dispersed private farms were few, but, even so, their owners resided within the existingmoshavot. They were not, therefore, seperate settlements. Publicly funded training farms were also set-up, and an early, unsuccessful, attempt to establish a cooperative farm also dates to this period. But these were also not genuine settlements. There were, in addition, a number of workers' quarters which were attached to plantation centers or worker settlements attached to existingmoshavot. All these settlement types tended to be nucleated. The discussion of the reasons for the dominance of nucleation is based on an analysis of documents and other sources of the 1882–1914 period. The factors are cultural, communal, and ideological as well as economic. The need for grouping together was stimulated by security and religious needs, but also by lack of experience and insufficient familiarity with the land and its political system. Other factors were the intricate tenurial regulations and farm land use strategies. The availability of adequate documentation for this case provides a fairly unique opportunity for understanding the process of pattern formation.     

Settlement patterns of brachyuran megalopae in a Louisiana estuary

Artificial substrate collectors were used to sample settled brachyuran megalopae in Terrebonne Bay, Louisiana, northern Gulf of Mexico. Three taxa,Callinectes sapidus, Uca spp., andRhithropanopeus harrisii, were the most common settlers. Settlement occurred almost year-round, although settlement densities were highest in late summer and early fall. In 1990, all three taxa had several simultaneous settlement peaks; in 1991, one simultaneous settlement peak occurred. FewerC. sapidus andUca spp. settled in 1991 than in 1990, but settlement abundance ofR. harrissii was similar between years. Local weather events, such as heavy precipitation, may have influenced the lower abundances ofC. sapidus andUca spp. in 1991. The megalopae ofC. sapidus andUca spp., which re-invade the estuary from higher salinity offshore waters where larval development occurs, may have been more affected by the lower 1991 estuarine salinity values than the larvae ofR. harrissii, which are retained within the estuary throughout larval development. Settlement ofC. sapidus andUca spp. was correlated with maximum tidal height, tidal amplitude, salinity, temperature, and lunar phase. In 1990, settlement ofC. sapidus was correlated with lunar declination cycles; settlement peaks occurred during equatorial minimum amplitude tides. The settlement ofR. harrisii was associated with tidal amplitude and lunar phase. Associations between environmental variables and settlement of megalopae were not consistent between the two years sampled. The opposing or reinforcing effects of various environmental variables on settlement, e.g., tidal height and rainfall, are superimposed on long-term hydrologic cycles so that dramatically altered cycles of settlement occur among years.     

Framework for assessing probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time

This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of a_max and M_w). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted.     

Empirical Relationships Between the Elastic Settlement of Rigid Rectangular Foundations and the Settlement of the Respective Flexible Foundations

The problem of settlement of shallow foundations is among the most important ones in classical soil mechanics. And while for the settlement of flexible foundations elastic solutions are widely used, for rigid rectangular foundations where the actual contact pressure distribution is still unknown, the problem is approximated either analytically assuming a contact pressure distribution or semi‐empirically combining the theory of elasticity with experimental and/or numerical results. A third and often attractive choice is the use of simple empirical relationships or relevant tabulated values relating the elastic settlement of rigid foundations (ρ_R) with the settlement of the respective flexible foundations (e.g. at the center, ρ_Ce). Reviewing the relathionships of this third approach, the author revealed serious lack of consesous between the various sources; for example, according to the literature, ρ_R ranges between 68 and 125% of ρ_Ce, the time when it is well-known that ρ_R?<?ρ_Ce. In this paper, comparison of the settlement of 210 rigid foundation cases derived from 3D elastic finite element analysis, with the settlement of the respective flexible foundations derived from the theory of elasticity, led to simple empirical relationships between ρ_R and ρ_Ce as well as between ρ_R and ρ_Av (ρ_Av?=?average settlement of the flexible foundation) with coefficient of determination (R²) almost unity. The analysis showed that these relationships are largely independent of the aspect ratio of foundations and the thickness and Poisson’s ratio (ν) of the compressible medium, although separate relationships are given for ν?=?0.5, slightly increasing R². Finally, a correction factor for foundation rigidity is given exploting the known linear relationship that exists between the relative stiffness factor of foundations and settlement.

     

Mapping of settlements in high-resolution satellite imagery using high performance computing

Classifying urban land cover from high-resolution satellite imagery is challenging, and those challenges are compounded when the imagery databases are very large. Accurate land cover data is a crucial component of the population distribution modeling efforts of the Oak Ridge National Laboratory’s (ORNL) LandScan Program. Currently, LandScan Program imagery analysts manually interpret high-resolution (1–5 m) imagery to augment existing satellite-derived medium (30 m) and coarse (1 km) resolution land cover datasets. For LandScan, the high-resolution image archives that require interpretation are on the order of terabytes. The goal of this research is to automate human settlement mapping by utilizing ORNL’s high performance computing capabilities. Our algorithm employs gray-level and local edge-pattern co-occurrence matrices to generate texture and edge patterns. Areas of urban land cover correlate with statistical features derived from these texture and edge patterns. We have parallelized our algorithms for implementation on a 64-node system using a single instruction multiple data programming model (SIMD) with Message Passing Interface (MPI) as the communication mode. Our parallel-configured classifier performs 30–40 times faster than stand-alone alternatives. We have tested our system on IKONOS imagery. The early results are promising, pointing towards future large-scale classification of human settlements at high-resolution.     

Social vulnerability index for coastal communities at risk to hurricane hazard and a changing climate

This paper presents the development of the Coastal Community Social Vulnerability Index (CCSVI) in order to quantify the social vulnerability of hurricane-prone areas under various scenarios of climate change. The 2004–2005 Atlantic hurricane seasons is estimated to have caused 150 billion dollars in damages, and in recent years, the annual hurricane damage in the United States is estimated at around150 billion dollars in damages, and in recent years, the annual hurricane damage in the United States is estimated at around 6 billion. Hurricane intensity or/and frequency may change due to the increase in sea surface temperature as a result of climate change. Climate change is also predicted to cause a rise in sea levels, potentially resulting in higher storm surges. The CCSVI combines the intensity of hurricanes and hurricane-induced surge to create a comprehensive index that considers the effects of a changing climate. The main contributing factors of social vulnerability (such as race, age, gender, and socioeconomic status) in hurricane-prone areas are identified through a principal components analysis. The impact of social characteristics on the potential hurricane damage under various scenarios of climate change are evaluated using Miami-Dade County, Florida, as a case study location. This study finds that climate change may have a significant impact on the CCSVI.     

Superposed folding in the Honakere arm of the Chitradurga-Karighatta schist belt in the Dharwar tectonic province,southern India,and its bearing on the Sargur-Dharwar relation

The supracrustal enclave within the Peninsular Gneiss in the Honakere arm of the Chitradurga-Karighatta belt comprises tremolite-chlorite schists within which occur two bands of quartzite coalescing east of Jakkanahalli(12°39′N; 76°41′E), with an amphibolite band in the core. Very tight to isoclinal mesoscopic folds on compositional bands cut across in the hinge zones by an axial planar schistosity, and the nearly orthogonal relation between compositional bands and this schistosity at the termination of the tremolite-chlorite schist band near Javanahalli, points to the presence of a hinge of a large-scale, isoclinal early fold (F₁). That the map pattern, with an NNE-plunging upright antiform and a complementary synform of macroscopic scale, traces folds 'er generation (F ₂),is proved by the varying attitude of both compositional bands (S₀) and axial pranar schistosity (S ₁), which are effectively parallel in a major part of the area. A crenulation cleavage (S ₂) has developed parallel to the axial planes of theF ₂ folds at places. TheF ₂ folds range usually from open to rarely isoclinal style, with theF ₁ andF ₂ axes nearly parallel. Evidence of type 3 fold interference is also provided by the map pattern of a quartzite band in the Borikoppalu area to the north, coupled with younging directions from current bedding andS ₀ -S ₁ inter-relation. Although statistically theF ₁ andF ₂ linear structures have the same orientation, detailed studies of outcrops and hand specimens indicate that the two may make as high an angle as 90°. Usually, in these instances, theF ₁ lineations are unreliable around theF ₂ axes, implying that theF ₂ folding was by flexural slip. In zones with very tight to almost isoclinalF ₂ folding, however, buckling attendant with flattening has caused a spread of theF ₁ lineations almost in a plane. Initial divergence in orientation of theF ₁ lineations due to extreme flattening duringF ₁ folding has also resulted in a variation in the angle between theF ₁ andF ₂lineations in some instances. Upright later folding (F₃) with nearly E-W strike of axial planes has led to warps on schistosity, plunge reversals of theF ₁ andF ₂ axes, and increase in the angle between theF ₁ andF ₂ lineations at some places. Large-scale mapping in the Borikoppalu sector, where the supposed Sargur rocks with ENE ‘trend’ abut against the N-‘trending’ rocks of the Dharwar Supergroup, shows a continuity of rock formations and structures across the hinge of a large-scaleF ₂ fold. This observation renders the notion, that there is an angular unconformity here between the rocks of the Sargur Group and the Dharwar Supergroup, untenable.     

Prediction of long-term settlement on soft clay using shear wave velocity and damping characteristics

This paper presents a method of calculating long-term settlement of a loaded pad on soft clay at Klang, Selangor, Malaysia where the soil model is treated as an anelastic material of viscoelastic property. Initially, an elastic shear modulus (G) value from shear wave velocity profiles of the seismic tests from spectral analysis of surface wave (SASW) and continuous surface wave (CSW) tests was obtained. A value of damping (D) at an equivalent elastic strain is then calculated from the hysteresis of the plate load tests corrected to equivalent strain using the Damping–Strain formula. The calculated elastic settlement and its equivalent damping are then used to calculate the long-term settlement by applying the generalised viscoelastic formula. Comparisons to traditional methods of settlement predictions were made and the viscoelastic formula has shown better agreement to the observed settlement. Further modification of the settlement formula is introduced to improve the settlement accuracy to 10%.     

The centrality of Islam: Space,form and process

This paper considers the centralizing and unifying tendencies of Islamic space paying particular and direct attention to the nature and reality of the pilgrimage to Mecca, theHajj. For the human geographer both theHajj and the other pillars-foundations of Islamic belief provide a constancy and spatially reinforcing dynamic to facilitate at least a partial comprehension of the properties of a specific and large cultural region; the community of Islam. It is to be stressed that any singular concern with theHajj that fails to see it as a part or rite within a wider functioning Islam will do a disservice both to the pilgrimage itself and present an unacceptable view of Islam. The recent growth of theHajj is considered as part of the continuity and indeed mounting ebullience and vitality of Islam. Continuing population growths and developments in transport technologies that present increasing opportunities to a widening number of Muslims are outlined and the various transport modes utilized byHajjees are considered.