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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey 3 Future Program Emphasis The air-sea-land interface that comprises the nation's coastal and marine environments is one of the most important and complex environments on the earth's surface. In this zone, terrestrial, marine, crustal, and atmospheric processes and their interactions operate at various magnitudes and on highly variable time and space scales. Here oceanic and thick continental crusts meet in complex interactions that result in regionally variable uplift and subsidence, changing erosion and sedimentation patterns, volcanoes, and earthquakes. This complex environment forms the coastal areas that provide homes and recreational areas for millions of Americans, as well as the resource-rich continental shelves, slopes and plains of the U.S. Exclusive Economic Zone (EEZ). U.S. continental margins are in a constant state of natural and anthropogenic change and are increasingly being stressed. Earthquakes, coastal landslides, and erosion threaten large population areas along the western margin. Coastal erosion and degradation of biologically rich estuaries are increasing along the eastern continental margin. Rising sea level and rapid subsidence, along with human activities, are destroying one of the largest wetland regions along the northern Gulf of Mexico. In southern Florida and along the tropical islands of the Pacific and Caribbean, the abundantly diverse and rich coral reefs are degrading at an increasing rate. The U.S. continental margins are rich in a variety of living and nonliving resources. It is critical for the United States to have a national program of investigation of the geologic processes that influence these valuable assets. The study of such complex regions must be framed in terms of the geologic setting and be approached from a systems-science perspective (broad interdisciplinary and
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey integrated studies), rather than as a single discipline. The committee believes that the U.S. Geological Survey (USGS) is the appropriate federal agency to lead this effort through integrated efforts of its four divisions. The committee has identified three grand challenges that it believes should form the integrating principle common to all Coastal and Marine Geology Program (CMGP) efforts to fulfill the need for geological information about the nation's coastal and marine environments over the next few decades: establish the geologic framework of the U.S. coastal and marine regions, develop a national knowledge bank on the geologic framework of the country's coastal and marine regions, and develop a predictive capability based on an understanding of the geologic framework of U.S. coastal and marine regions. To adequately respond to these grand challenges the CMGP must change its structures and procedures. The three grand challenges (discussed in detail below) are intended to provide the CMGP with a long-term focus and are not site or issue specific. Again, these challenges are intended as an integrative principle that should be used to evaluate the relevance of a variety of projects over the next 10 to 15 years (or longer). The resulting investigative program will be varied; as the complexity of the continental margins varies spatially, the underlying need for information will vary temporally, and successful execution of a national investigative program will require a systems-science approach. Addressing these challenges will require that CMGP projects make greater use of expertise in other units of the USGS, other federal agencies, and academic institutions. Such expanded interactions should enable CMGP to better communicate the results of its efforts to its user community. Although the committee understands that the variability and complexity of the continental margins is a familiar concept to geoscientists in general, the following discussion is included here to help establish a framework for discussing CMGP's grand challenges and near-term focus areas. It is from this perspective that the committee then argues the value of the grand challenges that face the nation's coastal and marine regions. THE GEOLOGIC STRUCTURE OF THE CONTINENTAL MARGINS OF THE UNITED STATES When viewed collectively, the coastal and marine zones of the United States occupy some of the most geologically complex terrain in the world (Plate 5). These areas encompass a wide variety of geologic structures that represent almost the entire range of boundaries identified within the framework of plate tectonics—from mid-ocean ridges off the coasts of Oregon and Washington to subduction zones off the coast of Puerto Rico. This diversity results in differences in the
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey types of geologic processes that have operated, and are still operating, in the nearshore and offshore along the continental margins. Through time, this diversity also results in variations in the distributions of common coastal features, rivers, aquifers, marine and coastal habitat, and marine resources. This variability is perhaps most easily seen by comparing the geologic structure of the areas making up the continental margins of the United States, which can be categorized into eight major provinces: Province 1— The Pacific Northwest A volcanically and tectonically active province that includes a spreading center and a subductive compressive margin. The province is characterized by: volcanic and earthquake processes and massive active margin faulting; extensive hydrothermal activity along the spreading center, resulting in the formation of metal-rich sulfide deposits and chemosynthesis-based biological communities; areas of simultaneous rapid uplift and subsidence; a glacially shaped margin with a major river depositing large quantities of sediment that builds the edge of continental margin; and strong littoral currents, high persistent wave energy, and periodic tsunamis. Province 1 is one of the most complex, dynamic, and least understood of the U.S. continental margin. A systems-science view of the area starts with understanding the active oceanic rift generating new oceanic crust. This young, thin crust is being subducted under the continent and the subsequent melt zone forms a line of live volcanoes from northern California to British Columbia. Thus, a tectonic system is operating from the spreading center in the west to the compressive folds under the shelf and beach and to the active volcanoes. The present coastline runs at right angles across this tectonic grain and therefore the beaches and shelves have a complex history of uplift and subsidence. The active compressional history has resulted in a complex ocean-bottom bathymetry that is host to benthic life of the deep marine and the marvelous tidal pools of the Oregon coast. The landward extent of this complex tectonic system is represented by faults, earthquakes, mudslides, and volcanoes. Province 2— Central and Southern California A shearing margin characterized by: areas of extremely rapid uplift and subsidence; broad continental borderland with active real-time strike-slip faults associated with massive earthquakes;
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey numerous submarine canyons that tap a strong littoral river of sand derived from the Sierra Nevada Mountains; and moderate wave energy with episodic storm events and periodic tsunamis. The borderland area of California is one of the great strike-slip shearing areas of the world. Here the Pacific plate meets the North American plate with grinding and sometimes catastrophic results. The result has been an extremely complex margin of isolated, deep basins juxtaposed with uplifted blocks that are islands of shallow banks. In the north, the Klamath Mountains run to the edge of the sea. The deep lithospheric and crustal structure of the area still holds many secrets of the underlying foundation that are critical for earthquake prediction. The shearing motions between the two plates have resulted in narrow uplifting and subsiding beaches swept by strong currents and rivers of sand moving along the beaches, which are swept off into the deep offshore canyons. This formed the great deep-sea fan deposits of the area. The Sierra Nevada Mountains have been rising at a high rate and continue to feed sediment to the coastal zone. So, here as in the Pacific Northwest, the geologic system extends from the escarpment in the west to the Sierra Nevada Mountains to the east. It is imperative that the system be studied as a whole from land to the sea. Province 3— Western and Central Gulf Coast A river-dominated coastal system characterized by: a large persistent influx of river-borne sediments and freshwater and related density contrasts; high sediment loading, which causes rapid subsidence and diapiric salt intrusions; a low wave and tidal energy coastal zone that is periodically inundated by intense hurricanes; a broad, gentle continental shelf with complex localized salt withdrawal basins; broad wetlands supporting a highly diverse ecosystem; and an area of major oil and gas production, both onshore and offshore. In Cretaceous time this province was dominated by massive carbonate reefs along the margin of a new rift basin. Then, as the Rockies rose, huge volumes of sediment were carried south by river systems. This elastic sediment overwhelmed and killed the reefs, producing a wedge of sediment over 13 kilometers thick. Interbedded with these sediments were layers of salt formed during the early history of the gulf. Thus, as this mass of sediment began to slide southward into the newly formed Gulf of Mexico, great down-to-the basin faults formed in the
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey area parallel to the present shoreline. The resulting reefs, salt layers, and organically rich sediments became structurally deformed and formed natural traps of oil and gas. Province 4— Florida Platform A carbonate-dominated stable margin characterized by: tectonic stability; a vast area of modern carbonate accumulation overlying older carbonate deposits; low-lying wetlands characterized by broad marshes and mangrove forests; low wave and tide energy, storm and hurricane-influenced; and a complex coastal aquifer system. The Florida platform and the adjacent Bahamian platform have an ancient rift history linked to the formation of the Atlantic Ocean. The early extension and rifting led to a complex crust that includes dike-injected continental and volcanic crust overlain by thick reef deposits. The sediment from the rivers of the western Gulf of Mexico did not reach the area, hence prominent reefs exist there today. The warm Gulf Stream sweeps this stable platform, and tropical environments have developed the beaches and shelves in this unique province. This area experiences hurricanes and strong storms that periodically alter the marine environment. Province 5— East Coast A passive continental margin characterized by: an ancient rift margin; a mesotidal system with strong, persistent littoral currents; extensive, persistent beach-barrier estuary complexes; strong winter storms and passages of intense hurricanes; a continuous coastal sand stream; and a northeastern section dominated by remnants of Quaternary glaciation and coastal rebound. The east coast province in the south overlaps with the Florida platform at the wide Blake Plateau. The province extends from the Appalachian Mountains on the west through the coastline, across the continental shelves, and out to the marine slope. The coastal foundation and the related subsidence mechanisms and fault patterns must be understood as a system in order to understand the beaches and shelves. The central area receives sediment from moderate-sized rivers eroding the
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey old Appalachian foldbelt. This ancient rift margin is underlain by thick sequences of clastic sediment overlaying reefs. To the north, these sedimentary sequences overlie volcanic sections and the New England volcanic seamounts intersect the coast. The northern portion of this province possesses a coast and shelf that have been modified by the passage of great Pleistocene ice sheets. Since the retreat of these great sheets, the entire region has been slowly uplifted, rebounding from the removal of the great weight of ice. Like the southern portion, this region experiences severe storms, which, when coupled with the regional uplift, create great sea cliffs and a rocky shoreline. The fisheries that occur from the coastal estuaries seaward to the marine banks boast prolific marine life. Province 6— The Great Lakes A failed Precambrian rift system characterized by: extremely stable tectonics, and glacially-dominated landscape. The geologic setting of the Great Lakes is extremely complex. Lake Superior overlies an ancient failed rift system older than any mountain chain in North America, while Lake Michigan lies adjacent to a great Paleozoic basin and the other lakes over a variety of Precambrian crystalline rocks. Modified by much younger glacial activity, this area's geologic foundation offers the key to understanding the region's natural history and resource potential. Province 7— Alaska Our nation's most diverse coastal and marine province is characterized by: a southern margin with extreme vertical tectonics, no large rivers, and strong long-shore drift; an ice-scoured northern margin that is an ancient passive margin with drastic seasonal variations in depositional environment; and a western margin dominated by arc-related and strike-slip Tertiary basins that receive huge seasonal influxes of sediment; the highest rates of North American vertical tectonics of the Alaskan hinterland arc; wetlands that are greatly different from the other provinces because of their dominance by seasonal permafrost and arctic processes; and the most diverse and intense natural hazards in the country. One of the most complex provinces the Alaska province can be subdivided into three distinct geologic realms: The southern realm and the Aleutian Islands are part of the extensive Northern Pacific subduction zone. This compressional area is marked by deep
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey trenches, high mountains, and major earthquakes. The area is sculpted by ice and fast-flowing seasonal rivers. Fjords and glaciers are common, and they interact with the environment to form complex ecosystems. The Bering Sea marine realm is floored by many subsiding sedimentary basins and hosts the Yukon River delta. The sea ice and runoff features have a strong influence on the marine geology. The north coast of Alaska is a geologic system that extends from the Brooks Range seaward to the rifted continental margin. A persistent basement high supports the coastline. Like its southern counterpart in the Gulf of Mexico, organic-rich sediment and geologic structure have created extensive oil and gas deposits across the area. Province 8— Tropical Island Province Volcanic islands characterized by: highly variable tectonic and volcanic activity in which the dominant sedimentary deposits are biogenic or volcanogenic; variable but narrow continental margins cut by numerous submarine canyons bordered by adjacent deep-sea trenches; diverse tectonic uplift and subsidence patterns; high wave energy and episodic storm events; and variable hazards, including volcanic activity, coastal and submarine landslides, and tsunamis. The tropical islands cover extremely variable provinces from the volcanic island chain of the Hawaiian Islands and other Pacific islands to the Caribbean. Rapid tectonic movement, earthquakes, faults, and volcanoes form the geologic setting for varied ecosystems ranging from reefs and estuaries to deep marine habitats. The beaches are complex in such dynamic settings. The onshore island geology cannot be separated from the offshore analysis of such areas. These beautiful, dynamic areas have many natural hazards in common, including volcanoes, earthquakes, tsunamis, and mudslides. The distinctly different geologic characteristics of U.S. coastal and marine environments, as well as the variations in oceanographic circulation and weather patterns encountered, result from different geologic processes with diverse spatial and temporal scales that shape the coastlines and seafloor. Hence, understanding the dynamic interface between land, sea, and air and assessing how changes in the coastal ocean might impact ecosystems and human populations requires the determination of the interplay between the fundamental geologic framework of these regions and the more localized natural geologic processes. Furthermore, similarities in geologic processes among the regions help point out areas where understanding developed in one region can be used to advance understanding in another. The CMGP is uniquely qualified to conduct nearshore and
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey offshore marine geologic studies and to integrate the results to produce a national assessment of the geologic structure of the coastal and marine regions of the United States. Specifically, the committee recommends that CMGP undertake a series of eight regional assessments (i.e., conducted in the eight regions discussed above). These assessments should be designed and conducted in a systematic manner that focuses on differences and similarities among the regions (e.g., the assessments should address geologic processes that operate across region boundaries, as well as those specific to a region). These eight regional assessments should then form the input needed to frame a national assessment. Such an assessment is the focus of the three grand challenges envisioned by the committee. Grand Challenge 1: Establish the Geologic Framework of the U.S. Coastal and Marine Regions The CMGP has already compiled excellent regional and local studies but has yet to integrate this information into a comprehensive national assessment of the characteristics of U.S. continental margins. The committee recognizes that this is a change from the current mode, but it will bring a much needed rationale and focus to CMGP research. In addition, this approach will require a rethinking not only of headquarters leadership but also individual scientists at the local centers. A national assessment has to be based on sound fundamental, integrated science (which has been a characteristic of CMPG) but with a broad perspective framed by an understanding of the different geologic settings of the eight provinces of the continental margins. The committee believes that the CMGP is perfectly poised to answer this grand challenge and therefore recommends that it immediately begin planning for a long-term, integrated, and comprehensive assessment of the nation's coastal and marine regions. Although the grand challenge offered here is a thorough assessment of coastal and marine environments, the committee feels that there are several thematic research issues that the CMGP should address as part of the plan to develop a thorough understanding of the entire region: tectonic and volcanic processes associated with earthquakes, landslides, tsunamis, and the distribution of mineral resources; nearshore and coastal processes associated with shoreline change, biological zonations and habitat changes, groundwater and seawater interface and interaction, transport of contaminated sediments, and the distribution of mineral resources; and biogeochemical interactions affecting the mobility of pollutants and the distribution and quality of mineral and energy resources.
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey The relative importance of these thematic research issues will vary between and even in the major coastal and marine provinces discussed above, but all will require multidisciplinary approaches and alliances with other federal and state agencies. Although efforts to address the three grand challenges will, by their nature, need to be coordinated by program leadership, there should remain some room for individual scientific inquiry. In setting this first grand challenge, together with its component subthemes, the committee feels that, with recognition of the diversity of the eight major coastal and marine provinces, a greater need for interdisciplinary and national assessments will follow. It is no longer sufficient, for example, to document the erosion rate at a stretch of shoreline in response to storms without taking into account the influence of the associated geologic factors (tectonics, glacio-eustatic rebound, hydrology), which may have a stronger influence on erosion rates. By undertaking a systematic assessment of the geologic framework of coastal and marine environments these interrelated variables can be compared and fundamental causative factors determined. Erosion rates must be integrated with process models, geologic information, and ecosystem models if CMGP is to produce forecasts that lead to sound decisionmaking. Similarly, wetland loss along the Gulf Coast cannot be examined adequately through single-discipline studies; quantitative information on geologic, biologic, and geochemical settings must be integrated into the studies to make the sound predictions needed to support coastal management decisions. Along the western coastal margin, such coastal changes as landslides and erosion must be integrated into a broad-scale model that takes into account the dynamic tectonic nature of this coast. Lastly, to thoroughly understand and predict the rapid degradation of coastal coral reefs, we must not only study coral ecology but also include studies of the hydrologic, atmospheric, and geologic processes in these environments. Grand Challenge 2: Develop a National Knowledge Bank on the Geologic Framework of the Country's Coastal and Marine Regions This coastal and marine geological knowledge bank should serve as a comprehensive inventory of geologic data developed by all interested agencies, academic institutions, and state agencies much like the knowledge bank of U.S. oil and gas resources, which has been developed by the USGS energy resource program and the Minerals Management Service. Furthermore, the development of such an inventory would represent a unique opportunity to foster even greater cooperation with federal, state, and local partners. USGS and CMGP have unique access to many forms of data collected using public funds. CMGP can thus play an important role in making those data publicly accessible. In recent years, this has become somewhat easier to accomplish with the advent of electronic distribution systems (Internet or CD-ROM),
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey but much effort remains to bring some forms of data to the public. In the early years of the twenty-first century, distributed information issues will become more important, and USGS needs to seriously consider its role as an information distributor. The committee, therefore, envisions a knowledge bank that is far more comprehensive than a simple database or series of World Wide Web sites. The knowledge bank should be developed in Geographic Information System (GIS) format with multiple stacked and interrelated layers of data. Data should be systematically collected at the province scale but would be integrated at the national level. The challenge facing CMGP will be to define the types of layers and then translate them into information and then into a comprehensive knowledge bank. The national knowledge bank should be managed and maintained centrally. Its structure must be designed to support resource management and other science-based decisions by federal, state, and local agencies. Furthermore, this knowledge bank should be designed to become the foundation for the assessment of the health and well-being of the coastal and marine environment. Building such a knowledge base for wise custodial decisions should begin with the construction of a preliminary data model for each province using all available data and information (at many scales and disciplines). Subsequent gap analysis of data, information, and knowledge would reveal: the critical data sets needed to analyze or build a comprehensive data model of the province and the fundamental geologic questions that will define the most critical projects and data gathering efforts that are needed to build the data model for each province. This data gathering leads to or facilitates: systematic organization of data and information, development of pertinent questions about the geologic framework of the province and its active processes, selection and prioritization of projects for developing data that are lacking, and communication with other federal and state agencies and state geological surveys leading to cooperative ventures. Finally, development of a method to derive custom products on demand will likely raise questions regarding competition with the private sector—there are some existing businesses that function as resellers of USGS data, sometimes reprocessed for specific purposes, sometimes not. These are thorny issues that are beyond the scope of this study but that will need to be addressed by the USGS as a whole.
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Science for Decisionmaking: Coastal and Marine Geology at the U.S. Geological Survey Grand Challenge 3: Develop a Predictive Capability Based on an Understanding of the Geologic Framework of the U.S. Coastal and Marine Regions The third grand challenge reflects the importance of planning to the future environmental and economic health of U.S. coastal areas. Effective planning demands an understanding of the likely scenarios for change to the geologic framework of coastal environments, whether from long-term climate change or from extreme short-term events or human activities. As pointed out in the recent National Science Foundation planning document entitled The Future of Marine Geology and Geophysics, ''An important area of future research will be in characterizing and modeling (non-linear) systems in which the input forcing is known or can be measured and the system response can be inferred from the geologic record (geologic time scales) or from direct observation (human time scales)'' (NSF, 1999). CGMP, through efforts to address the first two grand challenges, should be in a strong position to lead or contribute efforts to understand the complex and often nonlinear geological processes of coastal and marine environments. The CMGP should expand and strengthen quantitative model development and change-forecast products to meet management needs for defining the future geologic framework of coastal margins. This approach is consistent with the pursuit of other grand challenges and with the scientific methods and the principles of adaptive management. As implied to several times in this and the previous chapter, the committee recognizes that reorganizing CMGP efforts will require that, at least initially, CMGP concentrate its efforts on fewer projects and develop a viable mechanism for identifying the near-term focus and adjusting that focus over time. The following chapter lays out one possible strategy for CMGP.
Representative terms from entire chapter: