Geologic image in the Kentucky Geological Survey data repository.Image Name: Image Date: 10/1/2007 Category: photo_culture Source: Potter, Paul Format: JPG Size (MB): 1.68 Pixel Dimensions: 1768 x 1174 Description: Historical plaque of the Stacker Furnace near Lake Barkley in Trigg County, KY. The source of the iron was ferruginous-cemented regolith formed during long, Tertiary weathering of the Fort Payne and Salem/Warsaw Formations.