Why were only the faces carved on Mount Rushmore?

The faces carved on Mount Rushmore were chosen to represent the nation's history and ideals, symbolizing the country's founding, expansion, and preservation. The sculptor, Gutzon Borglum, focused on the faces to convey the personalities and contributions of Presidents George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt, emphasizing their roles in shaping America. The mountain's granite composition also made it more feasible to carve the faces, while significant details would have been lost due to the scale of the monument.