Madison Group, Williston Basin (14)

Comments on Geologic Parameters

14 Porosity:

Movement along major faults and lineaments may affect porosity over a large area and through time, making porosity fracture important in the area. Contours in the porosity map represent the thickness of rock having porosity greater than or equal to 10 percent.

14 Map:

14 Reference:

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.

Downey, 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.