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Galena-Platteville Groups

Galena-Platteville Groups
State Illinois
Name Galena-Platteville Groups
Geologic age Ordovician
Comments Formations included in the Galena-Platteville groups are: in the southern part of the state (Wise Lake Limestone, Dunleith Limestone, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone) and in the northern part of the state (Dubuque Dolomite, Wise Lake Dolomite, Dunleith Dolomite, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone). The dolomite units are restricted to the northern part of the state. Based on the stratigraphic column on the 1967 paper map, collectively these two groups are about 45% limestone , 45% dolomite (locally cherty) and 10% shale.
Primary rock type limestone
Secondary rock type dolostone (dolomite)
Other rock types shale
Lithologic constituents
Major
Sedimentary > Carbonate > LimestoneFormations included in the Galena-Platteville groups are: in the southern part of the state (Wise Lake Limestone, Dunleith Limestone, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone) and in the northern part of the state (Dubuque Dolomite, Wise Lake Dolomite, Dunleith Dolomite, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone). The dolomite units are restricted to the northern part of the state. Based on the stratigraphic column on the 1967 paper map, collectively these two groups are about 45% limestone , 45% dolomite (locally cherty) and 10% shale.
Sedimentary > Carbonate > DolostoneFormations included in the Galena-Platteville groups are: in the southern part of the state (Wise Lake Limestone, Dunleith Limestone, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone) and in the northern part of the state (Dubuque Dolomite, Wise Lake Dolomite, Dunleith Dolomite, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone). The dolomite units are restricted to the northern part of the state. Based on the stratigraphic column on the 1967 paper map, collectively these two groups are about 45% limestone , 45% dolomite (locally cherty) and 10% shale.
Minor
Sedimentary > Clastic > Mudstone > ShaleFormations included in the Galena-Platteville groups are: in the southern part of the state (Wise Lake Limestone, Dunleith Limestone, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone) and in the northern part of the state (Dubuque Dolomite, Wise Lake Dolomite, Dunleith Dolomite, Guttenburg Limestone, Kings Lake Limestone, Spechts Ferry Shale, Quimbys Mill Limestone, Nachusa Limestone, Grand Detour Limestone, Mifflin Limestone, Pecatonica Limestone). The dolomite units are restricted to the northern part of the state. Based on the stratigraphic column on the 1967 paper map, collectively these two groups are about 45% limestone , 45% dolomite (locally cherty) and 10% shale.
Map references
Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Unit references
Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Counties Alexander - Boone - Bureau - Calhoun - DeKalb - Grundy - Jersey - Jo Daviess - Kane - Kendall - La Salle - Lee - McHenry - Monroe - Ogle - Pike - Randolph - Stephenson - Whiteside - Winnebago