EMAG2v3: Earth Magnetic Anomaly Grid at 2-arc-minute Resolution, Version 3NOAA's National Centers for Environmental Information (NCEI)EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThe magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:Tips for using this web map:View the legend or toggle layers on/off with the buttons in the upper-right.Click on the map to see a popup reporting the data value at that location. Click on the arrow scroll through values for the Upward Continued (UpCont), Sea Level, and Error grids.The latitude/longitude of the mouse pointer is displayed in the lower-left.The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (data values)

Geology was researched and compiled for use in studies of ecosystem health, environmental impact, soils, groundwater, land use, tectonics, crustal genesis, sedimentary provenance, and any others that could benefit from geographically referenced geological data.

The Washington DC Area geologic map database (DCDB) provides geologic map information of areas to the NW, W, and SW of Washington, DC to various professionals and private citizens who have uses for geologic data. Digital, geographically referenced, geologic data is more versatile than traditional hard copy maps, and facilitates the examination of relationships between numerous aspects of the geology and other types of data such as: land-use data, vegetation characteristics, surface water flow and chemistry, and various types of remotely sensed images. The DCDB was created by combining Arc/Info coverages, designing a Microsoft (MS) Access database, and populating this database. Proposed improvements to the DCDB include the addition of more geochemical, structural, and hydrologic data.

Data are provided in several common GIS formats and MS Access database files. The geologic data themes included are bedrock, surficial, faults and fold axes, neat line, structural data, and sinkholes; the base themes are political boundaries, roads, elevation contours, and hydrography.

Data were originally collected in UTM coordinates, zone 18, NAD 1927, and projected to geographic coordinates (Lat/Long), NAD 1983. The data base is accompanied by large format color maps, a readme.txt file, and a explanatory PDF pamphlet.

The map and descriptions offer information that may be used for: land-use planning (e.g. selecting land fill sites, greenbelts, avoiding geologic hazards), for finding aggregate resources (crushed rock, sand, and gravel), for study of geomorphology and Quaternary geology. Geologic hazards (e.g., landslides, swelling soils, heaving bedrock, and flooding) known to be located in, or characteristic of some mapped units, were identified.

Surficial deposits in the quadrangle partially record depositional events of the Quaternary Period (the most recent 1.8 million years). Some events such as floods are familiar to persons living in the area, while other recorded events are pre-historical. The latter include glaciation, probable large earthquakes, protracted drought, and widespread deposition of sand and silt by wind. At least twice in the past 200,000 years (most recently about 30,000 to 12,000 years ago) global cooling caused glaciers to form along the Continental Divide. The glaciers advanced down valleys in the Front Range, deeply eroded the bedrock, and deposited moraines (map units tbg, tbj) and outwash (ggq, gge). On the plains (east part of map), eolian sand (es), stabilized dune sand (ed), and loess (elb) are present and in places contain buried paleosols. These deposits indicate that periods of sand dune deposition alternated with periods of stabilized dunes and soil formation.

Thirty-nine types of surficial geologic deposits and residual materials of Quaternary age are described and mapped in the greater Denver area, in part of the Front Range, and in the piedmont and plains east of Denver, Boulder, and Castle Rock. Descriptions appear in the pamphlet that accompanies the map. Landslide deposits, colluvium, residuum, alluvium, and other deposits or materials are described in terms of predominant grain size, mineral or rock composition (e.g., gypsiferous, calcareous, granitic, andesitic), thickness of deposits, and other physical characteristics. Origins and ages of the deposits and geologic hazards related to them are noted. Many lines between geologic units on our map were placed by generalizing contacts on published maps. However, in 1997-1999 we mapped new boundaries, as well. The map was projected to the UTM projection. This large map area extends from the Continental Divide near Winter Park and Fairplay ( on the west edge), eastward about 107 mi (172 km); and extends from Boulder on the north edge to Woodland Park at the south edge (68 mi; 109 km).

Compilation scale: 1:250,000. Map is available in digital and print-on-demand paper formats. Deposits are described in terms of predominant grain size, mineralogic and lithologic composition, general thickness, and geologic hazards, if any, relevant geologic historical information and paleosoil information, if any. Thirty- nine map units of deposits include 5 alluvium types, 15 colluvia, 6 residua, 3 types of eolian deposits, 2 periglacial/disintegrated deposits, 3 tills, 2 landslide units, 2 glaciofluvial units, and 1 diamicton. An additional map unit depicts large areas of mostly bare bedrock.

The physical properties of the surficial materials were compiled from published soil and geologic maps and reports, our field observations, and from earth science journal articles. Selected deposits in the field were checked for conformity to descriptions of map units by the Quaternary geologist who compiled the surficial geologic map units.

FILES INCLUDED IN THIS DATA SET:

denvpoly: polygon coverage containing geologic unit contacts and labels. denvline: arc coverage containing faults. geol_sfo.lin: This lineset file defines geologic line types in the geologically themed coverages. geoscamp2.mrk: This markerset file defines the geologic markers in the geologically themed coverages. color524.shd: This shadeset file defines the cmyk values of colors assigned to polygons in the geologically themed coverages.

EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThis tile layer displays a color relief image of the EMAG2v3 (Upward Continued) rendered with a "hillshade" effect to simulate a 3D surface. A coastline is also provided for reference. The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (provides data values)

Stress maps show the orientation of the current maximum horizontal stress (SHmax) in the earth's crust. Assuming that the vertical stress (SV) is a principal stress, SHmax defines the orientation of the 3D stress tensor; the minimum horizontal stress Shmin is than perpendicular to SHmax. In stress maps SHmax orientations are represented as lines of different lengths. The length of the line is a measure of the quality of data and the symbol shows the stress indicator and the color the stress regime. The stress data are freely available and part of the World Stress Map (WSM) project. For more information about the data and criteria of data analysis and quality mapping are plotted along the WSM website at http://www.world-stress-map.org. The stress map of Great Britain and Ireland 2022 is based on the WSM database release 2016. All data records have been checked and we added a number of new data from earthquake focal mechanisms from the national earthquake catalog and borehole data. The number of data records has increased from n=377 in the WSM 2016 to n=474 in this map. Some locations and assigned quality of WSM 2016 data were corrected due to new information. The digital version of the map is a layered pdf generated with GMT (Wessel et al., 2019) using the topography of Tozer et al. (2019). We also provide on a regular 0.1° grid values of the mean SHmax orientation which have a standard deviation < 25°. The mean SHmax orientation is estimated using the tool stress2grid of Ziegler and Heidbach (2019). For this estimation we used only data records with A-C quality and applied weights according to data quality and distance to the grid points. The stress map is available at the landing page of the GFZ Data Services at http://doi.org/10.5880/WSM.GreatBritainIreland2022 where further information is provided.

The data set for the Cougar Buttes quadrangle has been prepared by the Southern California Areal Mapping Project (SCAMP), a cooperative project sponsored jointly by the U.S. Geological Survey and the California Division of Mines and Geology, as part of an ongoing effort to utilize a Geographical Information System (GIS) format to create a regional digital geologic database for southern California. This regional database is being developed as a contribution to the National Geologic Map Data Base of the National Cooperative Geologic Mapping Program of the USGS. Development of the data set for the Cougar Buttes quadrangle has also been supported by the Mojave Water Agency and U.S. Forest Service, San Bernardino National Forest.

The digital geologic map database for the Cougar Buttes quadrangle has been created as a general-purpose data set that is applicable to other land-related investigations in the earth and biological sciences. In cooperation with the Water Resources Division of the U.S. Geological Survey, we have used our mapping in the Cougar Buttes and adjoining quadrangles together with well log data to develop a hydrogeologic framework for the basin. In an effort to understand surficial processes and to provide a base suitable for ecosystem assessment, we have differentiated surficial veneers on piedmont and pediment surfaces and distinguished the various substrates found beneath these veneers. Currently, the geologic database for the Cougar Buttes quadrangle is being applied in groundwater investigations in the Lucerne Valley basin (USGS, Water Resources Division), in biological species studies of the Cushenbury Canyon area (U.S. Forest Service, San Bernardino National Forest), and in the study of soils on various Quaternary landscape surfaces on the north piedmont of the San Bernardino Mountains (University of New Mexico). The Cougar Buttes database is not suitable for site-specific geologic evaluations at scales greater than 1:24,000 (1 in = 2,000 ft).

This data set maps and describes the geology of the Cougar Buttes 7.5' quadrangle, San Bernardino County, California. Created using Environmental Systems Research Institute's ARC/INFO software, the data base consists of the following items: (1) a map coverage showing geologic contacts and units, (2) a separate coverage layer showing structural data, (3) a scanned topographic base at a scale of 1:24,000, and (4) attribute tables for geologic units (polygons), contacts (arcs), and site-specific data (points). The data base is accompanied by a readme file and this metadata file. In addition, the data set includes the following graphic and text products: (1) A portable document file (.pdf) containing a browse-graphic of the geologic map on a 1:24,000 topographic base. The map is accompanied by a marginal explanation consisting of a Description of Map Units (DMU), a Correlation of Map Units (CMU), and a key to point and line symbols. (2) Separate .pdf files of the DMU and CMU, individually. (3) A PostScript graphic plot-file containing the geologic map on a 1:24,000 topographic base accompanied by the marginal explanation. (4) A pamphlet that summarizes the late Cenozoic geology of the Cougar Buttes quadrangle.

The geologic map data base contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs, including low-altitude color and black-and-white photographs and high-altitude infrared photographs. The map was created by transferring lines from the aerial photographs to a 1:24,000 topographic base via a mylar orthophoto-quadrangle or by using a PG-2 plotter. The map was then scribed, scanned, and imported into ARC/INFO, where the database was built. Within the database, geologic contacts are represented as lines (arcs), geologic units as polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum and link it to other tables (.rel) that provide more detailed geologic information.

This data collection is associated with the publication: Müller, R. D., Sdrolias, M., Gaina, C., Steinberger, B., & Heine, C. (2008). Long-term sea-level fluctuations driven by ocean basin dynamics. Science, 319(5868), 1357-1362. doi: 10.1126/science.1151540

Publication Abstract

We establish the locations and geometry of mid ocean ridges through time on the basis of marine magnetic anomaly identifications, geological information such as paleomagnetic data from terranes and microcontinents, especially in the Tethys Ocean, mid-oceanic ridge subduction events and the rules of plate tectonics. Based on a global set of tectonic plate rotations we construct a set of refined seafloor isochrons following the interpolation technique outlined by Müller et al. (1997; 2008) but including a multitude of additional data. Using a published age-depth relationship (GDH-1), we compute the depth-area distribution of the ocean basins. We choose GDH-1 for converting age to depth because this relationship is based on sediment-corrected depths without excluding data from hotspot swells and seamounts. Therefore GDH-1 provides a good average fit to sediment unloaded oceanic basement depths and is preferable for predicting the average oceanic basement depth through time, including thermally rejuvenated lithosphere, as compared to models that reflect ocean depth changes related to plate ageing through time only. Three additional factors play a significant role in controlling global ocean basin depth through time, namely the generation of oceanic large igneous provinces (LIPS), oceanic sedimentation (2) and changes in oceanic crustal area. We create a set of paleo-bathymetry maps by adding major oceanic plateaus and sediment thickness to our reconstructed basement depth maps. These maps allow us to compute oceanic crustal area and mean depth through time.

Authors and Institutions

R. Dietmar Müller - EarthByte Research Group, School of Geosciences, The University of Sydney, Australia. ORCID: 0000-0002-3334-5764

Maria Sdrolias (now Maria Seton) - EarthByte Research Group, School of Geosciences, The University of Sydney, Australia. ORCID: 0000-0001-8541-1367

Carmen Gaina - Center for Geodynamics, Geological Survey of Norway, Norway

Bernhard Steinberger - Center for Geodynamics, Geological Survey of Norway, Norway

Christian Heine - EarthByte Research Group, School of Geosciences, The University of Sydney, Australia

Overview of Resources Contained

This data collection includes a reconstruction of the global age-area and depth-area distribution of ocean floor since the Early Cretaceous (140 Ma), in 1 million year increments. Paleo-bathymetry since 140 Ma was also computed in 1 million year increments.

List of Resources

Note: For details on the files included in this data collection, see “Description_of_Resources.txt”.

Note: For information on file formats and what programs to use to interact with various file formats, see “File_Formats_and_Recommended_Programs.txt”.

• Raw XYZ data (.txt, total 30.04 GB)
• Gridded data (.nc, total 2.99 GB)
• Time-dependent images (.jpg, total 49 MB)
• Present-day maps (.jpg, .kmz, .tif, total 159.3 MB)
• Colour palette files (.cpt, total 16 KB)

For more information on this data collection, and links to other datasets from the EarthByte Research Group please visit EarthByte

For more information about using GPlates, including tutorials and a user manual please visit GPlates or EarthByte

EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThis tile layer displays a color relief image of the EMAG2v3 (Upward Continued) rendered with a "hillshade" effect to simulate a 3D surface. A coastline is also provided for reference. The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (provides data values)

This web map provides a customized world basemap uniquely symbolized and focused on the Caribbean region. It takes its inspiration from a printed atlas plate and pull-down scholastic classroom maps. The map emphasizes the geographic and political features in the design. This vector tile layer is built using the same data sources used for the World Topographic Map and other Esri basemaps. The use of country level polygons are preassigned with eight different colors. It also includes the global graticule features as well as landform labels of physical features. This map is designed for use with and includes the shaded relief layer. Alignment of boundaries is a presentation of the feature provided by our data vendors and does not imply endorsement by Esri or any governing authority.Use this MapThis map is designed to be used as a basemap for overlaying other layers of information or as a stand-alone reference map. You can add layers to this web map and save as your own map. If you like, you can add this web map to a custom basemap gallery for others in your organization to use in creating web maps. If you would like to add this map as a layer in other maps you are creating, you may use the tile layer item referenced in this map.Customize this MapBecause this map includes a vector tile layer, you can customize the map to change its content and symbology. You are able to turn on and off layers, change symbols for layers, switch to alternate local language (in some areas), and refine the treatment of disputed boundaries. For details on how to customize this map, please refer to these articles on the ArcGIS Online Blog.Fonts available for use in the style resource directory are under the OFL, Open Font License.This map was designed and created by Cindy Prostak.

EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThis map service has several sub-layers:EMAG2v3 (Upward Continued). Values in nTEMAG2v3 (Sea Level). Values in nTEMAG2v3 (Upward Continued) color relief image rendered with a "hillshade" effect to simulate a 3D surfaceEMAG2v3 (Sea Level) color relief image rendered with a "hillshade" effect to simulate a 3D surfaceData Source Code mapEstimated error (nT)A coastline is also provided for reference.The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map service (this service)Image service (provides data values)

This web map provides a customized world basemap uniquely symbolized. It takes its inspiration from a printed atlas plate and pull-down scholastic classroom maps. The map emphasizes the geographic and political features in the design. This vector tile layer is built using the same data sources used for the World Topographic Map and other Esri basemaps. The use of country level polygons are preassigned with eight different colors. It also includes the global graticule features as well as landform labels of physical features. This map is designed for use with and includes the shaded relief layer. Alignment of boundaries is a presentation of the feature provided by our data vendors and does not imply endorsement by Esri or any governing authority.Use this MapThis map is designed to be used as a basemap for overlaying other layers of information or as a stand-alone reference map. You can add layers to this web map and save as your own map. If you like, you can add this web map to a custom basemap gallery for others in your organization to use in creating web maps. If you would like to add this map as a layer in other maps you are creating, you may use the tile layer item referenced in this map.Customize this MapBecause this map includes a vector tile layer, you can customize the map to change its content and symbology. You are able to turn on and off layers, change symbols for layers, switch to alternate local language (in some areas), and refine the treatment of disputed boundaries. For details on how to customize this map, please refer to these articles on the ArcGIS Online Blog.Fonts available for use in the style resource directory are under the OFL, Open Font License.This map was designed and created by Cindy Prostak.

EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThis image service is based on an ArcGIS mosaic dataset, providing access to these grids:EMAG2v3 (Upward Continued). Values in nTEMAG2v3 (Sea Level). Values in nTEstimated error (nT)The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (this service; provides data values)

EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThis map service has several sub-layers:EMAG2v3 (Upward Continued). Values in nTEMAG2v3 (Sea Level). Values in nTEMAG2v3 (Upward Continued) color relief image rendered with a "hillshade" effect to simulate a 3D surfaceEMAG2v3 (Sea Level) color relief image rendered with a "hillshade" effect to simulate a 3D surfaceData Source Code mapEstimated error (nT)A coastline is also provided for reference.The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map service (this service)Image service (provides data values)

This is a representation of the EMAG2v3 grid as an "elevation" layer for use in web scenes, such as EMAG2v3: Earth Magnetic Anomaly Grid - Web Scene with Elevation.EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThe EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of purple and blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (provides data values)