known for snapping when they got wet, they made the 308 foot decent in just over twoerfa hours. theyll r had arrived in the canyon. and what a magnificent canyon it is. carved by the river for the last 160 thousand years, the grand canyon of the yellowstone is a work in progress. today it is 24 miles long. 1200 feet in depth. and 4,000 feet wide. tomorrow it will be a little bigger.ak every daens thy it gets deeper d wider as hydrothermal activity weakening the rock that lines it. that rock is rich in iron