AGGREGATING DATA: CREATING A MICHIGAN STATE-WIDE AGGREGATE RESOURCE MAP WITH LIMITED HISTORIC GEOLOGIC MAPPING

The state of Michigan awarded the Michigan Geological Survey (MGS) five years of funding to map the distribution of aggregate resources throughout the state. Michigan relies heavily on glacially derived sand and gravel as aggregate sources and, in limited regions, crushed carbonate rocks. This project aims to create a state-wide inventory of current and historic aggregate mines showing the surface area affected by mining, and a 1:24k scale geologic map of aggregate rich landforms showing where aggregate resources could be developed or protected to meet future demand.

Aggregate resource maps are typically a derivative product of traditional surficial and bedrock geologic maps. However, creating a derivative product is not an option for this new effort due to Michigan’s unique circumstances of having a dormant geological survey for many years. The most recent statewide surficial geology map was published by Farrand and Bell in 1982 but relied heavily on 1950s data. Additional surficial geologic mapping in the state since the 1980s covers only about one third of the state at scales ranging from 1:24k up to 1:200k and is limited primarily to Southwest Michigan and the central Upper Peninsula. New aggregate resource mapping is foundational for future analysis of aggregate resources including assessments and estimates of the amount of material removed from mining operations and long-term community planning.

In this work, we will discuss the methods being used by MGS to create the aggregate mine inventory as well as the methods and mapping philosophy behind the state-wide 1:24k scale aggregate resource map. Data sources for both products include LiDAR digital elevation models, air photos, historic aggregate mining records, soil surveys, water well records, and geotechnical borehole records. The resulting map products will be produced in a standard schema based on the GeMS standard to be easily incorporated into future and current mapping efforts including Quaternary geologic maps and hydrogeologic mapping. Our discussion will focus on the challenges of this project, including the challenge of building a consistent map product with a large team of mappers, strategies for quality control amongst mappers, and the unique challenges of creating aggregate resource maps in areas without modern geologic maps as a base.