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?
Are the en-echalon gashes related to an additional force vector? Is there a tension or shear force pulling the rock apart and opening these voids in addition to compression? So two forces a almost right angles to each other acting simultaneously?
I’m afraid I don’t see the en echelon tension gashes you’re referring to. Which photo set do they appear in?
Photos three, five, etc. I assume that means you see them as having another cause.
The open holes? Those are sites of preferential weathering, etched out along cleavage planes. They are surficial features, not through-going features like tension gashes.