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Over geologic timescales, C[O.sub.2] is emitted from the Earth's interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions (1). Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion (1,2) are superimposed on fluctuations in organic carbon burial (3). Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation (1,2,4). Widespread observations of a recent (0-5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them (4-6). Accelerated uplift and global cooling have been given as possible causes (2,4,6,7), but because of the links between rates of erosion and the correlated rate of weathering (8,9), an increase in the drawdown of C[O.sub.2] that is predicted to follow may be the cause of global climate change instead (2). However, globally, rates of uplift cannot increase every where in the way that apparent sedimentation rates do (4,10). Moreover, proxy records of past atmospheric C[O.sub.2] provide no evidence for this large reduction in recent C[O.sub.2] concentrations (11,12). Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record (13). As evidence, we recast the ocean dissolved [sup.10]Be/[sup.9]Be isotope system as a weathering proxy spanning the past ~12 Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and temporally averaged weathering rates., Studies of both the suspended and the dissolved loads of the world's largest rivers and of hill-slope denudation have shown a strong link between physical erosion and chemical weathering (8,9). [...]

Erosion and water-quality investigations are often conducted on small plots or watersheds, and under natural or artificial precipitation. Research objectives require flow measurement and sampling when large sediment concentrations occur. [...]

********** Soil loss was modeled to assess erosion potential at Camp Williams Army National Guard Training Facility in northern Utah (40.5° N, 112° E). Erosion models are available to estimate [...]

1 Large, infrequent disturbances can exert a dominant influence on the structure and dynamics of forested landscapes and in Westland, New Zealand there is evidence of at least three massive earthquakes within the last 650 years. We reconstructed the history of forest disturbance in two study areas, totalling 1412 ha, to quantify the role of such disturbance in structuring the conifer/hardwood forests. 2 We divided the study area into different land-surface types, aged trees on each land surface and identified cohorts of trees established in response to past disturbance. The type of disturbance (tree fall or erosion/sedimentation event) that initiated cohort establishment was determined from the type of land surface and other physical evidence. We also dated abrupt growth releases or suppressions in tree rings to aid disturbance history reconstruction. 3 Erosion and sedimentation events dominated the disturbance regime, affecting 86% of the study area in the last 650 years. Catchment-wide episodes of forest cohort-initiating disturbances were centred around 1820-30, 1710-20, 1610-20 and 1460 AD. Of the 51 cohorts identified in the study area, 47 were initiated during one of these episodes, when disturbance by erosion or sedimentation affected from 10-50% of the study area. Consequently, over 80% of the forested area currently comprises simple, first generation cohorts of trees established after catastrophic disturbance. Only 14% of the study area is more complex, all-aged forest. 4 Three disturbance episodes coincide with the three most recent Alpine fault earthquakes (c. 1717, 1630 and 1460 AD), while one coincides with earthquakes recorded to the south of the study catchment in 1826 AD. Age structures from throughout Westland show that extensive, similar-aged, post-earthquake cohorts of trees are a feature of the region, suggesting that infrequent, massive earthquakes are the dominant coarse-scale disturbance agent, triggering episodes of major erosion and sedimentation and leaving a strong imprint on the forest structure. Key-words: age/forest cohort, disturbance history reconstruction, erosion and sedimentation, landslides, terraces, tree rings

This paper looks at the use of laser technology, which has been used to provide high resolution images of underwater objects, to examine the morphology and size of sand particles eroded during benthic sediment transport under turbulent shear flow. Implications of sediment and carbon cycling within estuaries are discussed.

There are four main mechanisms through which glacial erosion may produce topographic relief, according to research giving quantitative information about the processes of erosion and relief production. These mechanisms are ice buttressing of rock slopes, valley widening and formation of hanging valleys and overdeepenings. There are three mechanisms by which glacial erosion may lead to a reduction in some elements of relief. These are reduction of fluvial erosion downstream of glaciers, concentration of erosion at higher elevations and possible acceleration of summit-lowering rates in the near-glacial environment.

Erosion risk assessment should incorporate various data sources for increased accuracy in predictions. These include mapping geomorphologically sensitive regions, weather pattern research and continuous rain-gauge information. Deforestation and vegetation removal have contributed to extended periods of erosion in Spain's Pyrenees, resulting from timber logging, overgrazing, fires and slope cultivation.

Research on natural hazards and erosion in Scandinavia provides valuable environmental and safety data on mountainous regions. The data can help clarify links between climatic changes and hazardous events, and assist in the development of safety programs for tourism and other industries in mountain and downstream locations. Climatic warming has been found to contribute to both snowmelt- and rainstorm-triggered flooding.

The CRP was initiated to remove environmentally fragile areas from crop production. Approximately 14.8 million hectares (36.5 million acres) of cropland, primarily west of the Mississippi, were enrolled in this [...]

An experimental program has been conducted to examine the feasibility of using seawater solar ponds in mariculture operations along the Texas gulf coast to protect fish crops from the potentially lethal, cold temperatures experienced in outdoor ponds. Seawater solar ponds in the form of floating thermal refuge areas are proposed as a method for reducing the loss of heat from small sections of a pond. Gradient zone erosion under various ambient and operating conditions is examined. Comparisons with previous laboratory studies show a much lower entrainment rate in the natural environment. For conditions which are typical of those encountered in mariculture pond operation, the entrainment rate was found to depend only weakly on the Richardson number. For these conditions, a simple (linear) correlation of entrainment rate with wind speed was developed.

The oldest greenstone successions with angular unconformity indicating an ancient erosion surface were newly discovered to be under the rocks of 3.46-Gyr Warrawoona Group in the Pilbara craton of Australia. This discovery supports the tectonic evolutionary models that believe during the first billion years of Earth's history, the early Archaeon period, considerable volumes of continental crust were already present The unconformity dates to between 3.47 and 3.46 Gyr and those greenstones must have been on an already rigid, buoyant and cool crust.

New research indicates that a shift to a more erosive climate would bring a decrease or no change in topographic relief in active mountain ranges. This suggests a negative or absent coupling between cooling and mountain uplift. In tectonically active mountain ranges, a more erosive climate should cut relief in fluvial landscapes and lead to little change in relief in glaciated landscapes. It is suggested that erosion by alpine glaciers generates relief by lateral support for valley walls by glacial ice, valley widening and formation of hanging valleys and overdeepenings.

A game-theoretic model of heterogeneous producers is developed in order to identify the economic determinants of producer noncompliance with the conservations provisions on highly erodible lands. Both theoretical and empirical results indicate that the increased income transfers to agriculture will increase producer compliance and conservation activity on highly erodible lands.

The results of laboratory studies involving the application of high-speed liquid jets to solve this problem are reported. Results from high-speed video images are used to quality the principal erosion process.

The pattern and ages of relict landforms, such as terraces, that are incised by rivers provide the best record of changes in Earth's surface elevation over millennial to million-year timescales. [...]

ABSTRACT: More than 60% of Mexico's soil and water resources has been identified as being in a moderately to severely degraded condition. The objective for this Mexico-United States project was [...]

Soil erosion has off-site, as well as on-site consequences. Off-site erosion damages include sedimentation in reservoirs and waterways. The expenditure of resources for conservation programs, however, are usually based on on-site damages. Regions that could potentially benefit from off-site erosion reduction are identified, and are compared to a model of regions that are targeted using existing on-site erosion criteria. Given the divergence between the two models, it is suggested that the present procedure for targeting areas for soil conservation is inefficient and results in a poor allocation of resources. Conservation efforts should be planned around two factors: farm productivity (as is currently the case) and potential off-site benefits (as is proposed).

The General Accounting Office recently reported to Congress that soil conservation measures have not been adequate to meet the problems which confront them. Therefore, a new model for soil conservation,

Geology 37, 187-190 (2009) They might look like the footprints of giants or of alien visitors, but the quasi-geometric shapes adopted by some elongated lakes or ponds have a natural [...]