Three-Dimensional Surficial Geology of the Milan Quadrangle, Erie and Huron Counties, Ohio

Abstract

The Central Great Lakes Geologic Mapping Coalition (now the Great Lakes Geologic Mapping Coalition or GLGMC) was formed in the late 1990s between the USGS and a network of state geological surveys which border the Great Lakes. The GLGMC was tasked with creating innovative three-dimensional (3-D) mapping, models, and other means for displaying the complex near-surface geology common to these states. These 3-D products, along with associated databases could be used to assist decision-makers on projects including geologic hazards, groundwater, mineral industries, and land usage. The Milan 7.5-minute quadrangle (Erie and Huron Counties) in north-central Ohio was chosen as one of the pilot projects for this program. The Milan quadrangle is transitional in origin and includes glacio-lacustrine, shoreline, alluvial, and glacial processes making for extremely complex series of depositional environments. A number of data sources including water well log data, engineering boring logs, NRCS soil surveys, theses, and prior reports were used to compile a series of maps using ESRI ARC-GIS tools. Each identified geologic unit or zone was identified and displayed as a discrete body. The origin, composition, and geomorphology of each body are thoroughly discussed herein. The entire sequence of overlapping units is represented as a geologic map and cross-section at scale of 1:24,000. The geologic map is accompanied by both a bedrock topography and drift thickness maps. A thick, elongated body of sand in the center of the mapping area was identified as a potentially important economic resource. A number of derivative maps were produced that include aquifer potential, aggregate potential, aquifer recharge, landfill suitability, and suitability for excavation and construction.