{"accessLevel": "public", "bureauCode": ["010:12"], "contactPoint": {"@type": "vcard:Contact", "fn": "Jennifer S. Stanton", "hasEmail": "mailto:jstanton@usgs.gov"}, "description": "This geodatabase includes spatial datasets that represent the Silurian-Devonian \naquifers in the States of Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, Ohio, \nTennessee, and Wisconsin. Included are: \n(1) polygon extents; datasets that \nrepresent the aquifer system extent, and the entire extent subdivided into subareas, \n(2) raster datasets for the altitude of the top and bottom surfaces of the entire aquifer \n(where data are available), and \n(3) altitude contours used to generate the surface rasters. The digitized contours are \nsupplied for reference.\n\t\t\nThe extent of the Silurian-Devonian aquifers is from the linework of the Silurian-Devonian \naquifer extent maps in U.S. Geological Survey U.S. Geological Survey Hydrologic Atlas 730, \nChapters J and K, (USGS HA 730-J, -K) and a digital version of the aquifer extent presented \nin the National Aquifer Code Reference List, available at \nhttp://water.usgs.gov/ogw/NatlAqCode-reflist.html , \"silurian.zip\". The extent was then \nmodified for each subarea:\n\t\t\nSubarea 1 (sa1): Primarily in Ohio and Indiana, subject of U.S. Geological Survey \nProfessional Paper 1423 B (USGS PP 1423B).\n\t\t\nSubarea 2 (sa2): In Iowa. Digital data were available from the Iowa Geologic Survey.\n\t\t\nSubarea 3 (sa3): Remaining area in Illinois, Wisconsin, Michigan, and Kentucky. \nExtent is that part of the National Aquifer Code Reference List polygon that \nremained when the areas of sa1 and sa2 were removed.\n\t\t\nThe altitude and thickness contours that were available for each subarea were \ncompiled or generated from georeferenced figures of altitude contours in \nUSGS PP 1423B for sa1, digital data from IAGS for sa2. There were no \nvertical data for sa3. \n\t\t\nThe resultant top and bottom altitude values were interpolated into surface rasters \nwithin a GIS using tools that create hydrologically correct surfaces from contour data, \nderive the altitude from the thickness (depth from the land surface), and merge the \nsubareas into a single surface. The primary tool was an enhanced version of \"Topo to Raster\" \nused in ArcGIS, ArcMap, Esri 2014.  The raster surfaces were corrected in the areas where \nthe altitude of an underlying layer of the aquifer exceeded the altitude of an overlying layer.", "distribution": [{"@type": "dcat:Distribution", "accessURL": "https://water.usgs.gov/lookup/getspatial?ds47slrdvn_a10", "description": "Landing page for access to the data", "format": "XML", "mediaType": "application/http", "title": "Digital Data"}, {"@type": "dcat:Distribution", "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.617a906e-a558-4e0d-92b9-1463f648f19f.xml", "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"}], "identifier": "http://datainventory.doi.gov/id/dataset/USGS_617a906e-a558-4e0d-92b9-1463f648f19f", "keyword": ["Devonian", "Illinois", "Indiana", "Iowa", "Kentucky", "Michigan", "Missouri", "Ohio", "Silurian", "Silurian-Devonian", "Tennessee", "USGS:617a906e-a558-4e0d-92b9-1463f648f19f", "United States", "Wisconsin", "aquifer", "aquifer system", "extent", "groundwater", "inlandWaters"], "modified": "2020-11-17T00:00:00Z", "publisher": {"@type": "org:Organization", "name": "U.S. Geological Survey"}, "spatial": "-96.467269197, 34.679503069, -81.580344116, 46.716678272", "theme": ["geospatial"], "title": "Geodatabase of the datasets that represent the three subareas of the Silurian-Devonian aquifer, Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, Ohio, Tennessee, and Wisconsin"}