Deformation bands, Hillsdale Canyon, Utah

&lt;p&gt;This sandstone is highly porous, and when subjected to tectonic stresses deforms through the development of deformation bands. &amp;nbsp; The bands resemble tiny veins, but microscopically they can be seen to be composed of crushed quartz grains. &amp;nbsp;The progressive deformation proceeds through compaction and loss of porosity along a thin zone, grain-to-grain stresses causing cataclastic deformation of the quartz, and then a jumping of the same process to another part of the rock, where porous.&lt;/p&gt;

Whereabouts

Hillsdale Canyon is on the west side of the Paunsaugunt plateau in southern Utah. I collected this specimen there in ~1999. The deformation bands there are in the form of tiny thrusts, causing shortening. I like the delicacy of development of deformation bands expressed in this small rock.

Age & Formation

Straight Cliffs Formation of Upper Cretaceous age, ~70 Ma.

QTVR

deformation_bands.mov771.36 KB