Frederick Jackson Turner Was

Frederick Jackson Turner was

A) a painter of American western landscapes.
B) a historian who put forth the thesis that the frontier was the key to the American character.
C) the author of Ramona , a tale of doomed love set on a California Spanish-Mexican ranch.
D) a one-armed veteran of the Civil War who charted the Colorado River through the Grand Canyon.
E) the author of Roughing It , a mining novel.