The Wyoming State Geological Survey (WSGS) has recently updated its statewide expansive soils layer found on its online Wyoming Geologic Hazards Map.
The updated expansive soils layer is intended to display the location of geologic formations with the potential of containing shrink-swell clays, which may lead to the development of expansive soils. The most common shrink-swell clays in Wyoming are sodium montmorillonite (also known as bentonite) and calcium montmorillonite. Changes in moisture cause expansive soils to expand or contract, which can cause damage to roadways, foundations, sidewalks, and other infrastructure.
The creators of the updated layer used existing geologic data to highlight geologic formations and units that may contain bentonite or calcium montmorillonite (shown as a “low hazard” in the map) and areas of the state that have documented occurrences of expansive soils (shown as a “moderate hazard”).
The intention of the online geologic hazards map is to provide regional information to be used by the public for general purposes. Detailed site-specific geotechnical studies are strongly recommended for any location.