The Deformation of Early Linear Structures in Areas of Repeated Folding

The geometry of originally rectilinear structures deformed during a later phase of fold movement is described. Lineations lying on a surface which is deformed by concentric folding have their locus on a partial cone (stereogram plots show a partial small circle pattern), whereas those lying on a surface folded in a similar manner have their locus on a plane (stereogram plots show a great circle pattern). A method of determining the actual movement or a-direction of particles during similar folding is described. The fold axis is not necessarily at right angles to this a-direction.