• Three main lacustrine facies are recorded above the basement breccia that provide evidence of the Devonian Shetland environment (Mykura, 1976; Allen, 1981). These include: (1) horizontal and cross-stratified sandstones with interbedded siltstones and mudstones. The shift between fine and coarse bedding suggests a lake marginal environment with wave action producing the rippled laminated sandstones; (2) rippled siltstones characterized by cross and horizontal lamination. The presence of plant remains and shrinkage cracks suggests this was a transitional lake environment with intermediate-to-continuous wave agitation; (3) laminated and unlaminated siltstones and mudstones with fish remains and no evidence of current or wave action. This is the horizon where Stegotrachelus is preserved.