. "Blue River Group"@en . . . . "43133473"^^ . "The Blue River Group is a geologic group in Illinois. It preserves fossils dating back to the Carboniferous period."@en . . . "1159"^^ . . . . . . "Blue River Group"@en . . . . . . . . . . . . . . . . "1096181823"^^ . "The Blue River Group is a geologic group in Illinois. It preserves fossils dating back to the Carboniferous period."@en .