Grand Canyon White Water River Trip on Colorado River. The Great Unconformity in the Blacktail Canyon.
"THE GREAT INCONGRUITY" IN BLACKTAIL SIDE CANYON, GRAND CANYON—BETWEEN 'RANDY'S ROCK' CAMP & 'FOOTBALL FIELD' CAMP, NO. 1993
[I]There are 2 layers of rock, but the difference in age between the two layers is 1.2 billion years.[/I]