Southwestern Iowa, unlike other parts of the State, does not have plentiful near-surface supplies of stone available for highway construction purposes. The long and intensive search for such road material by quarrymen, highway engineers, geologists, and others interested in all phases of stone use resulted in a growing conviction that the only hope of locating new and significant deposits lay in a regional geological survey. Further, such a survey would result in the delineation of areas where exploration should be economically feasible as well as those areas where exploration would have little or no chance of success. These views formed the foundation for de-veloping the project covered by this report under a cooperative agreement with the Iowa Highway Research Board of the Iowa State Highway Commission. The aims of the project were (1) to locate and describe all consolidated rocks found in place at the surface, or penetrated by drilling or other means; (2) to correlate these rocks geologically; (3) to assemble this information and the valid geological inferences from it into cross sections and maps showing the type of bedrock, thickness of overburden and rock structure; and (4) to write appropriate comments so that the potential usefulness and the most promising sites for future exploration or expansion for stone quarries can be readily seen and be of maximum value. The report was prepared with the knowledge that its chief immediate use would be by highway engineers and geologists, county engineers, materials producers, and prospectors. To facilitate their use of the report, certain phases were stressed and some standard methods of presentation and arrangement were not rigidly followed. The scientific integrity of the report is not compromised by these deviations from the formal scientific writing practices, nor is the value of the report for other uses thereby lessened
