26 October 2014

Bedding / cleavage relations in the Stephen Formation, Yoho NP

Posted by Callan Bentley

Good afternoon! Here are a few photos, both plain and annotated, showing the relationship between primary sedimentary bedding and tectonic cleavage in the “tectonised Stephen” Formation atop the Cathedral Escarpment (in Yoho National Park), just northeast of the Walcott Quarry where the (thicker, basinward) Stephen Formation hosts the Burgess Shale.

IMG_3169

IMG_3169_1

IMG_3219

IMG_3219_1

Weathering exploits both these planes of weakness…

IMG_3220

IMG_3220_1

Here, the cleavage is more planar at the bottom of the sample, and more curved toward the top – probably due to subsequent folding?

IMG_3221

IMG_3221_1