Faulted Navajo Sandstone with polish and slickenlines, Circle Cliffs uplift, Utah

&lt;p&gt;This is a great example of what happens when faulting ‘takes off’ along the margin of a zone of deformation bands. &amp;nbsp;The host rock with porous matrix is the brown-orange part of this rock. &amp;nbsp;The white ‘layer’ is the zone of deformation bands. &amp;nbsp;The surface of the zone of deformation bands is a classic fault surface, complete with excellent polish an slickenlines. &amp;nbsp;It is one of the two smoothest fault surfaces I ‘own.’&lt;/p&gt;

Whereabouts

I collected this rock in 1998 in Sheets Gulch in Capitol Reef National Park, along the Waterpocket fold. The deformation bands in Navajo Sandstone at Sheets Gulch are strike-slip in nature. This is the smoothest fault surface I own. When stresses run high near the time of mid-term exams, I encourage students to chill out by rubbing their hands over this great fault surface, and experiencing the soothing effect.

Age & Formation

Navajo Sandstone of Jurrassic age, i.e., ~170 Ma.