26 October 2014
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.
Weathering exploits both these planes of weakness…
Here, the cleavage is more planar at the bottom of the sample, and more curved toward the top – probably due to subsequent folding?