GEOLOGICAL HISTORY
The geological history of the metamorphic complex is difficult to correlate due to the tectonic boundary (Park 1970) between the Tollie gneiss and the Gairloch supracrustal group. It is observed that the deformation that formed the Tollie Antiform (D4) can be correlated to the deformation that formed the foliation surfaces in the Supracrustal group (c.f. Gairloch supracrustal group structural section of the report). However given the more complex structural history of the Tollie gneiss it is likely that this unit predates the Gairloch supracrustal groups precursors. As the Amphibolite sheet suite is absent from the Supracrustal group it would seem likely that the supracrustal group precursors post-date the intrusion of the Amphibolite sheet suite. Therefore the relative dating of the Gairloch supracrustal group is post D3 but pre D4 in the Tollie gneiss The tectonic history of the Tollie gneiss is fully described in the structural section of the report.
The tectonic contact between the Tollie gneiss and the Gairloch supracrustal group (Park op. cit.) post dates the D4 deformation and is likely to be D5.
Following the D5 minor folding and faulting episode the rocks where uplifted and eroded to give the pre Torridonian surface of the Lewisian metamorphic complex.
Torridonian sedimentary units were deposited by alluvial fans giving a landscape unconformity.
All of the above rocks ware formed in the Precambrian with the metamorphic rocks being Lewisian in age and the sedimentary rocks being Torridonian in age.
The events that occurred after the Torridonian are not observable from the geological record but no further deformations occurred in the area.
The final event in the geological history is modern uplift and erosion to reveal the Precambrian units.
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