BEDROCK MAPPING OF BUCHANAN AND EAST RIVER TOWNSHIPS, PAGE COUNTY, SOUTHWESTERN IOWA

Page County in southwestern Iowa is underlain by gently folded Pennsylvanian strata of the Forest City Basin. Studies of folding in southwestern Iowa have long been hampered by poor exposure and the difficulty in distinguishing among the many thin limestone and shale units. Although no commercial oil or gas has been found in Iowa to date, oil and gas fields in northeastern Kansas, southeastern Nebraska and northwestern Missouri lie along three subparallel lines that can be continued into Page County. Oil and gas exploration has begun in Page County, which emphasizes the need for accurate maps of bedrock folding. In contrast to most of southwestern Iowa, mapping at the member level in Buchanan (T67N, R36W) and East River (T68N, R36W) Townships in Page County is possible due to the occurrence of only one coal unit (Nodaway Coal) and one thick (10–12 feet) limestone unit (Ervine Creek Limestone). Thus, the many limestone and shale units can be identified by counting upward and downward from the Nodaway Coal or Ervine Creek Limestone. In addition, the installation of many tile drains over the last two decades has exposed many outcrops in creek beds that were unknown to previous workers. The above has provided an unprecedented opportunity for detailed (1:24,000) mapping of folding in southwestern Iowa.