 To the south appears a broad sheet of water -- the Yellowstone Lake.Although it is clear that the valley is named in honor of Ferdinand Vandeveer Hayden and his geological surveys of the Yellowstone region (his 1871 survey led to the creation of the park), there is little definitive evidence as to who actually named the valley.Some credit the Earl of Dunraven, during his visit in 1872, but the name first appeared on maps in 1880 in an annual report from superintendent Philetus Norris.