Map of klippe
View of klippe (as above)
CAM LOCH (NC225148 - NC223126)
Central and southern Assynt are interesting areas because they contain several erosional remnants of thrust sheets. These klippen are important for showing the original extent of thrust sheets and inspired early attempts at 3D visualisation in thrust belts. The largest of these structures is the Cam Loch klippe. However, there is controversy surrounding the correlation of the klippe with a specific major thrust sheet in eastern Assynt. One school suggests that the klippe forms part of the Ben More Thrust Sheet which original enveloped almost all of central and southern Assynt. However, to the ESE of the Cam Loch klippe the main trace of the Ben More thrust has Pipe Rock or younger Cambrian rocks directly in its hanging-wall. Presumably the Lower Quartzite and Precambrian units have been cut out against the thrust further to the east. For these units to be within the Cam Loch klippe would require the Ben More thrust to cut drastically down section. Thus an alternative is that the Cam Loch klippe forms part of a sheet distinct from and structurally higher than the Ben More. Regardless of the validity of these conclusions the site is important in providing a testing ground for the three dimensional analysis of thrust structures using cut-off line maps (e.g. Coward, 1985).
The klippe itself contains a major anticline that faces WNW and has a strongly overturned forelimb. It is a good example of a style of deformation termed 'thrust-propagation folding' (Williams and Chapman, 1983) whereby thrust ramping is accompanied by a buckling component reflecting a rate of thrust propagation that was slower than that of thrust displacement. Historically this deformation style underpins classical ideas of thrust formation developed in the Alps. In the Moine Thrust Belt, Peach et al. (1907) rejected this requirement of thrusting necessarily being preceded by folding since many thrusts show very little such deformation. The Cam Loch site, together with other examples of 'Sgonnan Mor structures' within the Ben More site, is important because it illustrates that both styles of thrusting, with or without preceding folding, may occur within the same thrust belt.