The Bear Gulch Beds, also known as the Bear Gulch Limestone, is a fossiliferous lagerstätte located in Central Montana. It constitutes a limestone layer laid down in the Mississippian epoch of the Carboniferous period, about 318 Ma. This lens of limestone was laid down in a surrounding matrix that indicates a landscape of mudflats and braided channels (linear sandstone seams) in fresh and brackish water, in an arid climate (gypsum formation). Magnetic orientation of particles relative to the bedding planes of the strata suggest a latitude of about 12°N, a tropical siting.