Jacob's Ladder. When the "blue lime"--the top of the red-wall limestone--is reached, one may study a fine piece of real canyon trail-making, locally called Jacob's Ladder. Here steps have been cut in the slippery and solid rocks, in some places built up with timbers, and thus made perfectly safe. It is customary for everybody to dismount here, so as to lighten the load. The well-trained saddle mules of El Tovar stables go up and down this part of the trail without hesitation.

Red-Wall Limestone. Standing on the summit of the red-wall limestone, we are again forcefully reminded that it is the most prominent member of the Grand Canyon strata. Its insistent mass is a thousand feet in thickness. The face of this wall, close before us, is carved into numerous alcoves, and as we near its base, we observe to the right a vast double-cornered recess known as Angel Alcove. From here it is interesting to look up to the rim and observe the peculiar and varied contour of the many pinnacles cut by wind and storm out of the cherty limestone.