Description: <DIV STYLE="text-align:Left;"><P STYLE="font-size:16ptmargin:7 0 7 0;"><SPAN><SPAN>The Big Snowy Group and the Charles are the top seal for the Madison Group. The top-seal map (Peterson, 1981, in Downey, 1986) shows maximum thickness for the Big Snowy Group of about 1,000 ft.</SPAN></SPAN></P><DIV><P><SPAN /></P></DIV></DIV>
Service Item Id: 17c967dc8ea64a47b35d6bb6a8dcb2ca
Copyright Text: 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.
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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.