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Click on any image to enlarge [above left] Big sky: the Black Hills are a world famous Cretacous ammonite locality. At this spot, in the south west corner of the state, a narrow layer of hard sandstone contains ammonites, clams, and scaphites [top right] Tom cracks open a plate of sandstone to reveal a large ammonite [center right] Spectacular clouds hang over Agate Beds State Park, SD [bottom right] Detail image of stones in the Agate Beds. Valuable fairburn agate — the state gem of South Dakota — can be found here by the patient collector |