Stock photography, photos: Tufa Formation or Frozen Waterfall Stock photos of A tufa formation, sometimes called a frozen waterfall, that formed over the eons in a small stream. This photograph was taken in the Lower Howard's Creek Nature and Heritage Preserve in the Bluegrass Region of Kentucky, USA  Photograph: © Jim Lane Click for a larger image and more information Keywords associated with this stock photo: tufa, frozen waterfall, limestone, travertine, calcium carbonate, natural wonder, scenic, Kentucky, KY, United States, USA, U.S. , calcareous, precipitation, deposit, closeup, close-up, close up