 This portion of the canyon is part of a National Natural Landmark, known as the Irvine Ranch Natural Landmarks.A listing of programs is available on the Landmarks' website.The beginning of the canyon is marked with signs which declare the road as private, which is half-true since the lower part of the road is privately maintained, although the county and, therefore the forest service, have an easement of public right-of-passage on the road, and have had that right for many decades.