This is one of the most beautiful canyons we have ever been through, with the Cimarron River flowing through it and the cliffs rising high above.  The Palisades Sill are spectacular cliffs cut by the Cimarron River through igneous rock (known as a sill). This monzonite rock was emplaced 40 million years ago when these Southern Rocky Mountains were being uplifted.  They are at 8000 feet elevation.