| This is a wide-angle view of the Burr Trail switchbacks area. The road
descends through the hogback ridge of Navajo Sandstone into the Strike
Valley. The Burr Trail road bends south in the Morrison Formation (Jurassic).
Strata of Cretaceous age are exposed across the valley in order from lowest
to highest: Dakota Sandstone (the first low sandstone ridge); this is
overlain by members of the Mancos Shale Formation: Tunuck Shale Member (gray
barren valley); Ferron Sandstone Member (another low brown ridge); Blue
Gate Shale Member (the steep, massive, gray, talus-covered slope); Emery
Sandstone (the caprock sandstone that forms the surface of the Tarantula Mesa -
the flat region that extends all the way to the Henry Mountains). In the distance,
Mt. Hillers (right) and Mt. Pennell (center-left) are two peaks formed of eroded
Tertiary-age igneous intrusions (Morrris and others, 2000; Billingsley and others, 1987). |
