The geology of the Firth of Lorne, as determined by seismic and dive sampling methods

Synopsis Marine studies in the Firth of Lorne have revealed the presence of heterogeneous basement and a constricted yet complex sedimentary basin. A total of forty three dive, dredge and borehole samples has allowed both the basement, which consists largely of Moinian, Torridonian and Old Red Sandstone, and the basin itself to be mapped. Using the criteria first employed by Kennedy to identify the line of the Great Glen fault, the course of the structure is extended along the Firth. Divergent fault splays with normal throw probably emanate from the principal Great Glen structure and in turn control the size and nature of the basin. The fill includes proven Triassic and Jurassic together with probable Cretaceous and Tertiary and a complex Quaternary sequence. Permo-Triassic syndepositional movements and late Kimmerian adjustments, together with mid-Tertiary activity are thought to have been the main periods of movement affecting the region.