Bulletin of the United States Geological SurveyThe Survey, 1956 - Geology |
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abundant abundant_ argillaceous beds and blue Behnke-Krug area blue beds blue-green brown shale buff C. E. Brown calcite chert is common chert is sparse_ Cherty unit drab clay bed clear calcite Collar elevation dark-brown dark-gray Decorah formation deposits Depth to water dolomite member gray Driller Dubuque County Dubuque subdistrict Durango feet west Ferry shale member finely to medium ft Depth feet Galena dolomite gray chert green shale Guttenberg limestone member hole 1 Location host rock Ion dolomite member Iowa iron content iron sulfide leached white chert light-gray limestone member oil Little Maquoketa River loess Maquoketa shale medium crystalline medium-grained member clay bed member gray beds member oil rock mottled Noncherty unit yellow-sandy Platteville formation pyrite Sample study shale member clay slight limonite staining sparse Spechts Ferry shale sphalerite strata Strike and dip Structure contours drawn study and logging Surficial syncline Total depth vuggy vugs Wallis area zinc and lead Zinc Iron