claim: Cordilleran Ice Sheet is made up mostly of snow.
evidence: William Romeyn Everdell is an American teacher and author .. Born in 1941 , he graduated from St. Paul 's School and from Princeton University .. Princeton University. Princeton University. A Woodrow Wilson Scholar and Fulbright Scholar , he holds a Master 's degree from Harvard University and a Ph.D in Modern Intellectual History from New York University .. Harvard University. Harvard University. New York University. New York University. He served during the Vietnam War as a U.S. Marine NCO in Morocco and marched against the war following his discharge in 1968 .. Vietnam War. Vietnam War. Morocco. Morocco. In 1970 , he began teaching at Saint Ann 's School , where he teaches world history .. He has been a regular contributor to the New York Times Book Review , and is the author of books and articles on intellectual history -LRB- history of ideas -RRB- .. New York Times. New York Times. One book The End of Kings -LRB- 1983 , 2000 -RRB- recaptures the historical definition of `` republic '' as a state not ruled by one person .. Another , The First Moderns -LRB- 1997 -RRB- redefines `` Modernism '' as the abandonment of the continuous in favor of the discrete in the arts and sciences that began in the West in 1872-1913 .. He has also written on teaching history , and served on the Test Development Committee for the first Advanced Placement World History Exams .. A member of the American Historical Association , he has also served as the president of the affiliated Organization of History Teachers , and of the East-Central American Society for Eighteenth-Century Studies .. American Historical Association. American Historical Association. He lives in Brooklyn with his wife , Barbara , who is an administrator at Saint Ann 's .. His sons , Josh and Chris , were born in 1971 and 1974 .