Report on the Examination of the Peterson #1 and Hummel 1 #4 Cores, 1981

(1981) Report on the Examination of the Peterson #1 and Hummel 1 #4 Cores, 1981. University of Iowa

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Abstract

During a temporary employment period (May 16 - September 15, 1980) with the Iowa Geological Survey, two cores were examined in order to better establish the strati graphic relationships between geologic units in the central part of Iowa and those in other parts of the state. The examined intervals of the Peterson #1 core from northeastern Webster County, and the Hummell #4 core from southwestern Dallas County, Iowa (Fig. 1) are shown to be primarily of late Middle to early Late Devonian age. The lowest part of the Peterson #1 core that was examined, however, was found to be Ordovician. Nine lithologic units were recognized in the Peterson core. The Hummell #4 core is divided into 3 such units. In addition to lithologies each of these units was examined in terms of faunal content, depositional environment, and biostratigraphy. Each of these criteria will be discussed separately for each unit of the two cores. Biostratigraphic interpretations were based primarily on conodont faunas. Not all recovered species had been identified at the time this report was written. Nevertheless, it is thought that the most biostratigraphically significant forms have been recognized, and further identifications will not greatly alter the interpretations presented herein.