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Cabrach - grussified gabbro and corestones

 

 

 

 

 

 

Cabrach - gabbro tor

 

 

 

 

 

 

 

 

Cabrach - ice-moulded tor

 

Tors of The Cabrach

The gabbro tors of the Cabrach are almost unique in Scotland in their basin rim and low-lying setting.  The tors are mainly <5 m high and adjacent road cuts show that the tors have emerged due to the weathering of gabbro to a granular gruss (Basham 1974). Towards Rhynie, glacial erosion has progressively modified the tors, stripping loose blocks and creating roches moutonnées and larger crags. The numerous glacially-transported corestones that litter the Insch basic igneous mass indicate that tors were widespread there prior to glaciation.

The tors lie on the rising ground on the eastern flank of the The Cabrach basin, the source of the River Deveron. The fill of Lower Old Red Sandstone on the basin floor requires that parts of the present landsurface are sub-Devonian in origin. The immature granular grusses developed on the gabbro are likely however to be mainly products of Pleistocene weathering, although kaolinitic weathering is described from nearby Clashindarroch Forest by Koppi (1977).