Deformation band shear zone, East Kaibab monocline, Utah


During the period 1994-1999 I invested a lot of time in southern Utah, mapping and analyzing deformation band shear zones.  I collected this rock along the East Kaibab monocline along the Cockscombs near Candyland.  The nature of the shear is extensional, normal slip.  I like this rock because it drives home the illusion that deformation are veins, when in fact they are shear zones.  Moreover, the ladder structure is ubiquitous in rocks marked by pervasive deformation bands, and it was a challenge to try to figure out how to ‘read them.’

Age & Formation
Navajo Sandstone of Jurassic age, ~170 Ma, laced with deformation bands that formed in latest Cretaceous to Eocene, i.e., ~70-55Ma.
navajo.mov1.78 MB