The USGS Law of the Sea project helps to determine the outer limits of the extended continental shelf (ECS) of the United States. The ECS is that portion of the continental shelf beyond 200 nautical miles. It is an important maritime zone that holds many resources and vital habitats for marine life. Its size may exceed one million square kilometers, encompassing areas in the Arctic, Atlantic, Bering Sea, Gulf of Mexico, western Pacific, and Pacific west coast. USGS provides geologic measurements and research to help define the ECS collaboratively with the Department of State, NOAA, and other federal agencies.
The Law of the Sea project integrates science and law. Article 76 of the Law of the Sea Convention sets forth rules for determining the outer limits of the continental shelf beyond 200 nautical miles (M). Defining the outer limits of the ECS is necessary for determining the exact extent of the area within which the United States exercises its sovereign rights and jurisdiction. The size of the U.S. ECS is roughly 1 million square kilometers, more than twice the area of the state of California. The resources in the U.S. ECS are worth many billions if not trillions of dollars.
Why study the ECS?
The United States, like other countries, has an inherent interest in knowing, and declaring to others, the exact extent of its ECS and thus the sovereign rights it is entitled to exercise in this part of the ocean. Defining those limits in concrete geographical terms provides the specificity and certainty necessary to protect, manage, and use the resources of the ECS. The collection and analysis of the data necessary to establish the outer limits of the U.S. ECS also provides a better scientific understanding of our continental margins. Department of State ECS FAQ
The USGS conducts research to provide geologic framework, seafloor processes, and sediment thickness measurements to identify and establish the outer limits of the U.S. ECS. With its national knowledge and expertise of the U.S. continental margins, USGS has responsibility for developing a database of sediment thickness and continental margin geology, assessing existing data, and developing scientific research opportunities. USGS conducts complex, lengthy field experiments in the regions beyond 200 M. USGS also advises the Department of State about the possible geologic criteria used by other coastal States to identify their ECS limits. Finally, this project includes a task to investigate the mineral resource potential of the U.S. EEZ and ECS. USGS studies help enable the federal government to make informed decisions relating to boundary negotiations, resource development, and resource conservation in the deep-water areas of the U.S. continental margins, including those beyond 200 M.
For this project, USGS works within the framework of a federal interagency U.S. ECS Task Force, chaired by the Department of State and co-vice-chaired by NOAA and Department of the Interior. The Task Force approves project goals and work plans that are developed by the three cooperating agencies.
USGS has led or participated in ten field programs in four regions to collect seismic reflection data to support delineation of the U.S. ECS. Because of the absence of seismic data in the area north of Alaska, the Arctic Ocean represents the largest seismic effort of the project (~17,000 km of seismic track data, collected collaboratively with the Geological Survey of Canada during six field programs in remote ice-covered areas). The Atlantic required the second largest effort (two field programs, ~5400 km of seismic track data). The Bering Sea and Gulf of Alaska each required one field effort, collecting ~3000 km of data in each region.
The USGS Law of the Sea project is a programmatic effort by the Coastal and Marine Hazards and Resources Program (CMHRP), involving participants from the Woods Hole Coastal and Marine Science Center (WHCMSC), the Pacific Coastal and Marine Science Center (PCMSC), the Geology, Minerals, Energy and Geophysics Science Center, and as well as the CMHRP Program Office. From 2002 through 2022, WHCMSC is home base for the active project. From 2023, Law of the Sea activity continues as a task within the USGS Global Marine Minerals project, based within PCMSC.
Below are other scientific efforts related to this project
Global Marine Mineral Resources
Delineating the U.S. Extended Continental Shelf
Below are data products associated with this project.
Woods Hole Coastal and Marine Science Center Sediment Laboratory

The Woods Hole Coastal and Marine Science Center Sediment Analysis Laboratory is a resource that performs analyses relating to grain size, mineralogy, composition, and sedimentary character of samples collected by WHCMSC researchers and their partners using state of the art techniques and analytical equipment.
Multibeam bathymetry and acoustic backscatter from the Alaskan region, Extended Continental Shelf Project, 2011 field season: Gulf of Alaska and Bering Sea
Detrital zircon geochronology and geochemistry data from the seafloor of the Bering Sea and adjacent river systems
Geophysical data collected along the Atlantic Continental Slope and Rise 2014, U.S. Geological Survey Field Activity 2014-011-FA, Cruise MGL1407
National Archive of Marine Seismic Surveys (NAMSS: A USGS data website of marine seismic reflection data within the U.S. Exclusive Economic Zone (EEZ)
Below are publications associated with this project.
Continental shelves as detrital mixers: U-Pb and Lu-Hf detrital zircon provenance of the Pleistocene–Holocene Bering Sea and its margins
Multiple melt source origin of the Line Islands (Pacific Ocean)
The role of pre-magmatic rifting in shaping a volcanic continental margin: An example from the Eastern North American Margin
Changes in sediment source areas to the Amerasia Basin, Arctic Ocean, over the past 5.5 million years based on radiogenic isotopes (Sr, Nd, Pb) of detritus from ferromanganese crusts
Refining the formation and early evolution of the Eastern North American Margin: New insights from multiscale magnetic anomaly analyses
Significance of northeast-trending features in Canada Basin, Arctic Ocean
Arctic deep-water ferromanganese-oxide deposits reflect the unique characteristics of the Arctic Ocean
Formation of Fe-Mn crusts within a continental margin environment
Processes of multibathyal aragonite undersaturation in the Arctic Ocean
Sources, distributions and dynamics of dissolved organic matter in the Canada and Makarov Basins
Marine phosphorites as potential resources for heavy rare earth elements and yttrium
Submarine landslides in Arctic sedimentation: Canada Basin
- Overview
The USGS Law of the Sea project helps to determine the outer limits of the extended continental shelf (ECS) of the United States. The ECS is that portion of the continental shelf beyond 200 nautical miles. It is an important maritime zone that holds many resources and vital habitats for marine life. Its size may exceed one million square kilometers, encompassing areas in the Arctic, Atlantic, Bering Sea, Gulf of Mexico, western Pacific, and Pacific west coast. USGS provides geologic measurements and research to help define the ECS collaboratively with the Department of State, NOAA, and other federal agencies.
R/V Marcus G. Langseth The Law of the Sea project integrates science and law. Article 76 of the Law of the Sea Convention sets forth rules for determining the outer limits of the continental shelf beyond 200 nautical miles (M). Defining the outer limits of the ECS is necessary for determining the exact extent of the area within which the United States exercises its sovereign rights and jurisdiction. The size of the U.S. ECS is roughly 1 million square kilometers, more than twice the area of the state of California. The resources in the U.S. ECS are worth many billions if not trillions of dollars.
Why study the ECS?
Ice conditions in the Arctic from CCGS Louis S. St-Laurent, a Canadian Coast Guard Heavy Arctic Icebreaker. The United States, like other countries, has an inherent interest in knowing, and declaring to others, the exact extent of its ECS and thus the sovereign rights it is entitled to exercise in this part of the ocean. Defining those limits in concrete geographical terms provides the specificity and certainty necessary to protect, manage, and use the resources of the ECS. The collection and analysis of the data necessary to establish the outer limits of the U.S. ECS also provides a better scientific understanding of our continental margins. Department of State ECS FAQ
The USGS conducts research to provide geologic framework, seafloor processes, and sediment thickness measurements to identify and establish the outer limits of the U.S. ECS. With its national knowledge and expertise of the U.S. continental margins, USGS has responsibility for developing a database of sediment thickness and continental margin geology, assessing existing data, and developing scientific research opportunities. USGS conducts complex, lengthy field experiments in the regions beyond 200 M. USGS also advises the Department of State about the possible geologic criteria used by other coastal States to identify their ECS limits. Finally, this project includes a task to investigate the mineral resource potential of the U.S. EEZ and ECS. USGS studies help enable the federal government to make informed decisions relating to boundary negotiations, resource development, and resource conservation in the deep-water areas of the U.S. continental margins, including those beyond 200 M.
Seismic Field Programs for USGS Extended Continental Shelf Research For this project, USGS works within the framework of a federal interagency U.S. ECS Task Force, chaired by the Department of State and co-vice-chaired by NOAA and Department of the Interior. The Task Force approves project goals and work plans that are developed by the three cooperating agencies.
USGS has led or participated in ten field programs in four regions to collect seismic reflection data to support delineation of the U.S. ECS. Because of the absence of seismic data in the area north of Alaska, the Arctic Ocean represents the largest seismic effort of the project (~17,000 km of seismic track data, collected collaboratively with the Geological Survey of Canada during six field programs in remote ice-covered areas). The Atlantic required the second largest effort (two field programs, ~5400 km of seismic track data). The Bering Sea and Gulf of Alaska each required one field effort, collecting ~3000 km of data in each region.
The USGS Law of the Sea project is a programmatic effort by the Coastal and Marine Hazards and Resources Program (CMHRP), involving participants from the Woods Hole Coastal and Marine Science Center (WHCMSC), the Pacific Coastal and Marine Science Center (PCMSC), the Geology, Minerals, Energy and Geophysics Science Center, and as well as the CMHRP Program Office. From 2002 through 2022, WHCMSC is home base for the active project. From 2023, Law of the Sea activity continues as a task within the USGS Global Marine Minerals project, based within PCMSC.
Seismic Lab aboard R/V Marcus G. Langseth Snowy owl visitor to CCGS Louis S. St-Laurent in the Arctic Ocean - Science
Below are other scientific efforts related to this project
Global Marine Mineral Resources
Researching seafloor mineral resources that occur within the U.S. Exclusive Economic Zone and areas beyond national jurisdictions.Delineating the U.S. Extended Continental Shelf
The United States has an interest in knowing the full extent of its continental shelf beyond 200 nautical miles from shore (called the extended continental shelf, or ECS) so that it can better protect, manage and use the resources of the seabed and subsoil contained therein. The USGS contributes to the ECS effort through membership and leadership on the interagency U.S. ECS Task Force, a group... - Data
Below are data products associated with this project.
Woods Hole Coastal and Marine Science Center Sediment LaboratoryThe Woods Hole Coastal and Marine Science Center Sediment Analysis Laboratory is a resource that performs analyses relating to grain size, mineralogy, composition, and sedimentary character of samples collected by WHCMSC researchers and their partners using state of the art techniques and analytical equipment.
Multibeam bathymetry and acoustic backscatter from the Alaskan region, Extended Continental Shelf Project, 2011 field season: Gulf of Alaska and Bering Sea
This publication releases swath bathymetry and backscatter datasets derived from multibeam bathymetric data acquired by the U.S. Geological Survey (USGS) on the R/V Marcus G. Langseth legs MGL1108 (transit) and MGL1109 in the Gulf of Alaska, and MGL1111 in the Bering Sea. Leg MGL1108 data were combined with leg MGL1109 data during processing. These data were acquired with a Kongsberg Simrad EM-122Detrital zircon geochronology and geochemistry data from the seafloor of the Bering Sea and adjacent river systems
This dataset archives geochronology and geochemistry measurements from detrital zircons collected from samples taken from the Bering Sea and its major feeder rivers.Geophysical data collected along the Atlantic Continental Slope and Rise 2014, U.S. Geological Survey Field Activity 2014-011-FA, Cruise MGL1407
In summer 2014, the U.S. Geological Survey conducted a 21-day geophysical program in deep water along the Atlantic continental margin by using R/V Marcus G. Langseth (Field Activity Number 2014-011-FA). The purpose of the seismic program was to collect multichannel seismic reflection and refraction data to determine sediment thickness. These data enable the United States to delineate its ExtendedNational Archive of Marine Seismic Surveys (NAMSS: A USGS data website of marine seismic reflection data within the U.S. Exclusive Economic Zone (EEZ)
The National Archive of Marine Seismic Surveys (NAMSS) is a marine seismic reflection profile data archive consisting of data acquired by or contributed to U.S. Department of the Interior agencies. The archived data were collected from 1975 to the present. They include marine seismic reflection profile data acquired originally for purposes of oil and gas exploration within the U.S. Exclusive Econo - Multimedia
- Publications
Below are publications associated with this project.
Filter Total Items: 44Continental shelves as detrital mixers: U-Pb and Lu-Hf detrital zircon provenance of the Pleistocene–Holocene Bering Sea and its margins
Continental shelves serve as critical transfer zones in sediment-routing systems, linking the terrestrial erosional and deep-water depositional domains. The degree to which clastic sediment is mixed and homogenized during transfer across broad shelves has important implications for understanding deep-sea detrital records. Wide continental shelves are thought to act as capacitors characterized by tMultiple melt source origin of the Line Islands (Pacific Ocean)
The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a hotspot-generated seamount chain; however, the lack of a predictable age progression has stymied previous models for the origin of this feature. We combined plate-tectonic reconstructions with seamount age dates and available geochemistry to develop a new model that involves multiple melt regions and muThe role of pre-magmatic rifting in shaping a volcanic continental margin: An example from the Eastern North American Margin
Both magmatic and tectonic processes contribute to the formation of volcanic continental margins. Such margins are thought to undergo extension across a narrow zone of lithospheric thinning (~100 km). New observations based on existing and reprocessed data from the Eastern North American Margin contradict this hypothesis. With ~64,000 km of 2‐D seismic data tied to 40 wells combined with publishedChanges in sediment source areas to the Amerasia Basin, Arctic Ocean, over the past 5.5 million years based on radiogenic isotopes (Sr, Nd, Pb) of detritus from ferromanganese crusts
Ferromanganese (FeMn) crusts provide a useful paleoenvironmental archive for studying the poorly understood climatic, oceanographic, and geologic evolution of the Arctic Ocean. This study is based on the identification and temporal reconstruction of sources and inferred transport pathways of terrigenous material in FeMn crusts collected from several sites across the Amerasia Basin. Samples from thRefining the formation and early evolution of the Eastern North American Margin: New insights from multiscale magnetic anomaly analyses
To investigate the oceanic lithosphere formation and early seafloor spreading history of the North Atlantic Ocean, we examine multiscale magnetic anomaly data from the Jurassic/Early Cretaceous age Eastern North American Margin (ENAM) between 31 and 40°N. We integrate newly acquired sea surface magnetic anomaly and seismic reflection data with publicly available aeromagnetic and composite magneticSignificance of northeast-trending features in Canada Basin, Arctic Ocean
Synthesis of seismic velocity, potential field, and geological data from Canada Basin and its surrounding continental margins suggests that a northeast-trending structural fabric has influenced the origin, evolution, and current tectonics of the basin. This structural fabric has a crustal origin, based on the persistence of these trends in upward continuation of total magnetic intensity data and vArctic deep-water ferromanganese-oxide deposits reflect the unique characteristics of the Arctic Ocean
Little is known about marine mineral deposits in the Arctic Ocean, an ocean dominated by continental shelf and basins semi-closed to deep-water circulation. Here, we present data for ferromanganese crusts and nodules collected from the Amerasia Arctic Ocean in 2008, 2009, and 2012 (HLY0805, HLY0905, HLY1202). We determined mineral and chemical compositions of the crusts and nodules and the onset oFormation of Fe-Mn crusts within a continental margin environment
This study examines Fe-Mn crusts that form on seamounts along the California continental-margin (CCM), within the United States 200 nautical mile exclusive economic zone. The study area extends from approximately 30° to 38° North latitudes and from 117° to 126° West longitudes. The area of study is a tectonically active northeast Pacific plate boundary region and is also part of the North PacificProcesses of multibathyal aragonite undersaturation in the Arctic Ocean
During 3 years of study (2010–2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic-derived and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite underSources, distributions and dynamics of dissolved organic matter in the Canada and Makarov Basins
A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. CMarine phosphorites as potential resources for heavy rare earth elements and yttrium
Marine phosphorites are known to concentrate rare earth elements and yttrium (REY) during early diagenetic formation. Much of the REY data available are decades old and incomplete, and there has not been a systematic study of REY distributions in marine phosphorite deposits that formed over a range of oceanic environments. Consequently, we initiated this study to determine if marine phosphorite deSubmarine landslides in Arctic sedimentation: Canada Basin
Canada Basin of the Arctic Ocean is the least studied ocean basin in the World. Marine seismic field programs were conducted over the past 6 years using Canadian and American icebreakers. These expeditions acquired more than 14,000 line-km of multibeam bathymetric and multi-channel seismic reflection data over abyssal plain, continental rise and slope regions of Canada Basin; areas where little - Partners