{ "culture": "en-US", "name": "", "guid": "", "catalogPath": "", "snippet": "Permeability Map for Madison Group, Williston Bay", "description": "

The development of karst, sink holes, caves, and solution breccias is common in the Madison Group, modifying the permeability. Movement along major faults and lineaments may have affected permeability over a large area and through time. Madison permeability is secondary to fracture permeability (Downey, 1984, 1986). Flow-net analysis assumes that a steady-state flow condition exists and no leakage is occurring from or to adjacent aquifers. The transmissivity is about 0,013 ft<\/SPAN><\/SPAN>2<\/SPAN><\/SPAN>/s (Konikow in Downey, 1984, 1986). Other studies suggest that some leakage from overlying rocks may be present and that the transmissivity value should be less than 0,013 ft<\/SPAN><\/SPAN>2<\/SPAN><\/SPAN>/s. According to Downey (1984, 1986), the variation in transmissivity values reported by several scientists is the result of local conditions and may not reflect the average on a regional scale. As a result of his analysis, Downey found that transmissivity values are related to porosity (fracturing porosity). A simulated transmissivity map by Downey (1986) was therefore added to the GIS data base. <\/SPAN><\/SPAN><\/P>

<\/P><\/DIV><\/DIV>", "summary": "Permeability Map for Madison Group, Williston Bay", "title": "Madison Permeability", "tags": [ "Madison Group", "Williston Basin" ], "type": "", "typeKeywords": [], "thumbnail": "", "url": "", "minScale": "NaN", "maxScale": "NaN", "spatialReference": "", "accessInformation": "Downey, J. S., 1986, Geohydrology of bedrock aquifers in the northern Great Plains in parts of Montana, North Dakota, South Dakota and Wyoming: U.S. Geological Survey Professional Paper 1402-E, 87 p.\n*\nDowney, J. S., 1984, Geohydrology of the Madison and associated aquifers in parts of Montana, North Dakota, South Dakota and Wyoming: U.S. Geological Survey Professional Paper 1273-G, 47 p.", "licenseInfo": "See access and use constraints information.", "portalUrl": "" }