Landscapes on the Edge New Horizons for Research on Earth's Surface (2010) / Chapter Skim
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1 The Importance of Earth Surface Processes
1 The Importance of Earth Surface Processes
Pages 13-34
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From page 13... ...
What plants and animals live in and along this stream, and how do biological processes -- including human activities -- affect the downstream flow of nutrients and water? Next, look about and wonder how this stream relates to its valley and the surrounding hillslopes.
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From page 14... ...
SOURCE: Photograph courtesy of Dorothy Merritts, Franklin and Marshall College, Lancaster, Pennsylvania. Other than a basic goal of explaining the form, composition, and evolution of landscapes, why might questions about Earth surface processes near a stream, or similar types of questions posed along a coastline or in a fragile arctic landscape, matter?
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From page 15... ...
These examples focus on how Earth surface processes are interconnected or "coupled" to each other, to the atmosphere, and to the Earth's interior; on the increasing human impact on Earth's surface, including climate change; and on new technologies that have spurred recent theoretical advances in Earth surface processes. These topics are elaborated in greater detail in Chapters 2 and 3.
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From page 16... ...
While the volume of rock drawn into a mountain belt is affected by Earth surface processes, the composition of the rock also is altered and this change can affect climate. Chemical weathering of rock freshly exposed in rapidly uplifting mountains affects the chemistry of water draining the mountains and can draw down carbon dioxide in the atmosphere, thereby influencing climate over relatively long periods of geologic time.
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From page 17... ...
reveals regional climatic processes that drive spatial variation in rates and processes of erosion that, in turn, influence tectonics. Clouds are banked along the northwestern side of the mountains (Southern Alps)
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From page 18... ...
; and the extent of agricultural land cover (including croplands and pastures) (middle and bottom)
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From page 19... ...
Can the ecological, hydrological, and geomorphic functions of marshes, streams, and floodplains that lie buried beneath reservoir sediment be recovered after dam breaching? In essence, each dam breach is an experiment in which scientists can investigate interconnected Earth surface processes.
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From page 20... ...
Colors represent scour amounts determined by calculating the difference between digital elevation models of post-dam removal topography generated from an airborne lidar (light detection and ranging) 1 survey and of pre-dam removal topography from photogrammetry and bathymetric surveys.
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From page 21... ...
Climate change affects all landscapes, influencing hydrology, flooding, water quality, nutrient loads, ecosystems, soil erosion, and landslide frequency. Retreating glaciers, for example, let loose large chunks of ice and freshwater while freshly eroded rock becomes exposed to weathering in the wake of the glaciers' retreating termini (Figure 1.5)
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From page 22... ...
. The needs for better methods of assessing and predicting soil erosion and sediment supply at a wide range of landscape scales, and for clarifying concepts that underpin public policy on these matters, suggest an important role for research in Earth surface processes.
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From page 23... ...
These broad-based studies are typical of modern approaches to understanding and quantifying the causes and effects of soil erosion and are central to the development of effective soil erosion control strategies.
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From page 24... ...
Lena Delta system reveal the interconnectedness among climate change, biota, soils, and landscapes at the centennial to millennial scale and the critical linkages between human activities and Earth surface processes. 1.3 NEW TECHNOLOGIES: MONITORING EARTH SURFACE PROCESSES AT HIGH RESOLUTION IN SPACE AND TIME The evolution and increasing availability of new measurement technologies has enabled many of the advances in Earth surface processes that are discussed throughout this report.
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From page 25... ...
Tundra wetlands in this delta store large amounts of carbon that potentially could be released by modern global warming. Attributed largely to human activity, warming accelerates permafrost thawing and the erosion of organic-rich delta sediments.
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From page 26... ...
Although many digital elevation data are coarse in scale for studying the features, for example, of mountain belts with long, high hillslopes, the data have been truly revolutionary. The advances in the past decade are akin to those of the 1960s in the fields of seismology and geophysics, when accessibility to global seismic and paleomagnetic data and new tools to process such signals spurred the plate tectonics revolution and greater understanding of Earth's subsurface processes.
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From page 27... ...
Comparison of Google Earth image (bottom, digital air photo) with two lidar-derived images for an area near Flathead Lake, Montana: "bare Earth" topography with vegetation removed (top left)
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From page 28... ...
Undoubtedly much more will be discovered as these new dating technologies are used to measure the rates of evolution of Earth's surface. 1.4 STUDy CONSIDERATIONS AND REPORT STRUCTURE Interdisciplinary research2 in Earth surface processes comprises the detailed investigation of contemporary processes that generate and degrade landscapes and change the properties of rocks and soil; the definition of how these processes have functioned over the long periods of time required for the evolution of surface conditions (composition, function, and form)
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From page 29... ...
. The BROES report first developed the concept of the "Critical Zone" as the "heterogeneous, near-surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources." In addition to these surface interactions, the investigation of Earth surface processes as developed in this report involves features and transfer processes that place greater emphasis on geological history and on interactions and feedbacks both with humans and with deep-Earth processes (e.g., tectonics)
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From page 30... ...
The production of cosmogenic nuclides in a wide range of Earth materials and knowledge of the production rates have led to a revolution in our ability to quantify the timing and rates of Earth surface processes from thousands to millions of years with radiogenic nuclides (7Be, 10Be, 14C, 26Al, 36Cl) , or even longer with stable nuclides (3He, 21Ne)
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From page 31... ...
Cosmogenic dating, in this case 10Be, provides chronologic control for different ages of alluvial fan surfaces offset along the northern Death Valley fault (fault strikes northwest to southeast along the western part of a lidar-derived bare-Earth topographic image)
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From page 32... ...
Nevertheless, significant advances will require developing quantitative predictive capability for how landscapes form, evolve, and respond to change. Such capability is especially important as Earth surface processes are increasingly altered by human activity and climate change.
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From page 33... ...
With new scientific questions about various components of the Earth system, opportunities and tools for research, rapid growth of the human population, and unprecedented changes in biota, land cover, process rates, and global climate, an appraisal of the study of Earth surface processes is both timely and crucial.
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