ROCKS OE THE NORTHERN HIGHLANDS. 395 



fact corresponds with what I have described as the usual position 

 of the quartzite on the western slopes of the Assynt ranges. 



Ben-na-creisag and Ben-an-Uarran* . — These are the two reddish- 

 looking hills which overhang the road south of Inchnadamtr on the east 

 side, between the igneous mass of Cnoc-na-Strone and the Stronch- ' 

 rubie cliffs. On Prof. Heddle's map they are coloured as " quart- 

 zite," but with a query. I have examined both from end to end, 

 and believe them to be blocks of Torridon Sandstone thrust up 

 between faults through the overlying members of the Assynt series. 

 At the south end of Ben-an-Uarran, the rock closely resembles the red 

 grit of Ben More ; but further to the north it passes into red sand- 

 stone of ordinary Torridon type. Ben-na-Creisag is of similar rock, 

 conglomerate as well as sandstone being present. The dips were 

 usually not very clear, but in Ben-na-Creisag they seemed to be 

 to the 1S".W. Descending to the west from the summit of Ben-an- 

 Uarran, we first come to quartzite of the seamy variety, with red 

 felspar bits, dipping into the hill; and beyond a little hollow 

 is white dolomite, which is first vertical and contorted ; then it 

 dips into the ridge ; lower down it dips away from it, and finally, 

 near the road, into the hill again. These facts point to inversion of 

 quartzite upon dolomite, an effect which would naturally be produced 

 by the upthrust of the Torridon, with lateral push from the east, just 

 as similar results have followed from like causes in the mountains fur- 

 ther east. Dolomite dips away from this hill at the north end. The 

 Torridon mass of Ben-na-Creisag appears to be entirely surrounded by 

 dolomite, which in some places dips towards it, and in others away 

 from it, the junction being frequently marked by "a line of debris. 



The Stronchrubie Basin. — This mass of dolomite approaches in 

 shape an equilateral triangle, the sides respectively facing to W., 

 N.E., and S. E. The western edge crops out in the well-known escarp- 

 ment which overhangs the road south of Inchnadamff, the strata 

 dipping easterly. Along the north-eastern margin the quartzite 

 of Ben Uarran passes below the dolomite, the dip being to the S.W. 

 To the S.E. the quartzite of Northern Brebag dips conformably 

 below the dolomite above Loch Maolack Corry, the inclination being 

 to the N.W. The dolomite therefore forms a true basin, the strata 

 dipping inwards from the three sides. 



Erom the facts adduced it will be seen that Prof. Nicol's descrip- 

 tion of Assynt is in its main points confirmed. He interprets the 

 structure of Ben More as " a nucleus of granitic gneiss and mica 

 slate, with intrusive igneous rocks, throwing off the quartzite all 

 around, as from a great centre of elevation ;" and this, omitting the 

 " igneous rock," which seems to have been his interpretation of 

 the overthrown Hebridean, is substantially accurate ; and he 

 truly affirms that " the limestone is everywhere troughed by the 

 quartzite." 



* This name must not be confounded with " Ben Uarran." 



