Today (6 July 02000) NPR's Morning Edition program aired a segment on an attempt to save information in a literally dying medium.
Seems that bored Basque sheepherders left a historical record in the late 1800's/early 1900s on the bark of Aspen trees. The trees have a natural lifespan of 70-100 years, so many of them are dead and the rest are dying.
"Tree Carvings -- Tristan Clum of member station KNAU reports on documenting dendroglyphs...tree carvings...near Flagstaff, Arizona. Starting in the late 1800's, sheepherders, many of from the Basque region of Northern Spain, carved basic messages or elaborate images into the bark of aspen trees in this area. Now the trees are dying, and historians are trying to compile information before it's too late. (4:58)"