To fold or not to fold

Meanwhile down south at Highwood Pass Jimmy Shale and his friends are upset about Susan Siltstone’s last comment. The shales are not happy that she is always so prominent and gives the impression that it was her idea and her work to deform in a ductile style. “That is a misrepresentation! We, the shales, made all the folding possible!” Jimmy protests. He knows how stiff and rigid Susan really is. “You would have broken apart without our support.” Jimmy is proud of his much softer and malleable nature in comparison to most other rocks. 

Susan scoffs. “Your work? That’s not true at all. I didn’t break because my siltstone layer is thin, just a few centimeters thick. That is the reason I folded easily.” Susan looks west to the top of Mount Tyrwhitt where the old Mississippian limestone layers tower high up into the sky. These guys broke apart during the forceful times of mountain building and are slanting to the southwest since then. “The limestones broke because they are stiff, and their layers are much thicker––tens of meters thick.”  

Mount Tyrwhitt with Missisippian limestone layers dipping to the southwest. Source: wikipedia.org

​“Yes, they are much thick than you and they are 200 million years older than us, but that’s not all. Don’t you see the difference?” Jimmy is flustered about Susan’s ignorance. “There are no shales around the limestone layers.” The whole mountain top is just made up of the stiff and rigid limestone layers. 
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Now she sees it. It never occurred to Susan before. She slowly wonders if Jimmy has a point here and it was not only her work to make these beautiful folds. “But why did I get lucky and have shales around me while others don’t?” Susan wonders how she got Jimmy around her. 
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