Where does drape collide?

In textile science, drape is a fabric's tendency to deform out of plane into graceful folds under its own weight, which is what makes one cloth hang in soft columns and another stand stiffly away from the body. Cusick's 1965 The dependence of fabric drape on bending and shear stiffness showed that this behaviour is governed jointly by the fabric's bending and shear rigidity and reduced it to a single drape coefficient measured on a drapemeter. The referent is a measurable mechanical property of a sheet, quantified by the fraction of a circular sample's area that its shadow still covers once it has draped over a smaller disc, and it is a different thing from a manufacturing forming step or a geological fold even though all three share the image of cloth falling over a form.[1]

Unit

The drape coefficient, the ratio of draped shadow area to undraped area of a circular sample

Recovery means

Not applicable

Measured by

Measured on a Cusick-type drapemeter as the drape coefficient, with bending and shear stiffness characterised separately

In structural geology, a drape fold (a type of forced fold) is a fold in a sedimentary cover sequence that forms because the cover is bent passively over a rigid basement block that has been offset along a fault, so the layers drape across the step rather than buckling under their own in-plane shortening. Stearns's 1978 Faulting and forced folding in the Rocky Mountains foreland described how foreland folds take their geometry from the shape of the faulted basement beneath them. The referent is a fold whose form is imposed by an underlying structure, measured by its geometry and the fault displacement that drove it, and it is unrelated to a fabric's hang or a composite forming step beyond the shared picture of a layer conforming to a shape below it.[2]

Unit

The fold geometry and the basement fault displacement that imposed it

Recovery means

Not applicable

Measured by

Characterised by cross-section geometry, limb dips, and the offset of the underlying faulted basement