Missouri River Corps of Rediscovery: Gates of the Prairie

"At this palce there is a large rock of 400 feet high wich stands immediately in the gap which the missouri makes on it's passage from the mountains; it is insulated from the neighbouring mountains by a handsome little plain which surrounds its base on 3 sides and the Missouri washes it's base on the other, leaving it on the Lard. as it decends. this rock I call the tower. It may be ascended with some difficulty nearly to its summit, and from it there is a most pleasing view of the country we are now about to leave. from it I saw this evening immence herds of buffaloe in the plains below."...