Mark Adams is the author of the new book, Tip Of The Iceberg: My 3,000 Mile Journey around Wild Alaska, The Last Great American Frontier . Adams retraces the famous 1899 expedition sponsored by railroad magnate Edward Harriman which included John Muir and George Bird Grinnell, founder of the Audubon Society. Adams describes the changes both man and climate have made on the Alaskan wilderness since that famous trip.