242 



C. CALLAWAY ON THE LIMESTONE 



ing to received views, this newer gneiss must overlie the limestone ; 

 and, if so, the force which contorted the former must also have 

 affected the latter. But though the limestone comes up to the 

 gneiss on both sides, its gentle south-east dip is not changed. It 

 would appear to be more reasonable to infer that the limestone was 

 deposited on the contorted gneiss, and that the latter was subse- 

 quently thrust up through the former between two parallel faults. 



c. The Quartzite. — The bay between the limestone promontory 

 of Leirinmohr on the west and the headland of Lewisian gneiss on 

 the east is occupied by the quartzite, which is also seen sloping 

 down from the flanks of Ben Keannabin to the bay and forms a 

 small outlier on the headland just named. It dips uniformly to the 

 north-east. In the western angle of the bay it is faulted (/ 4 ) against 

 the limestone. Both limestone and quartzite are crushed into thick 

 breccias at the junction, and on the bank immediately above the 

 limestone is seen dipping to the north-west, the strikes of the two 

 formations being, as in the former case, nearly at right angles. 



To sum up these results, it is clear that the metamorphic rocks, 

 quartzite and schist, have been affected by a force tilting them up 

 to the north-east, while the limestone forms a syncline whose axis 

 strikes to the south-south-west. How the limestone can hold a 

 conformable relation to the altered groups is a problem which the 

 advocates of the received view may fairly be called upon to solve. 



Though the metamorphic rocks occur in three distinct patches, it 

 is probable that they form a true succession. To the east of Loch 

 Eirriboll, the quartzite is overlain by gneiss of the Sango-Bay type, 

 which is surmounted by the flaggy group on Loch Hope. In Durness 

 the Sango-Bay gneiss must overlie the quartzite, since the latter 

 rests on the Lewisian gneiss ; and if the flags of Far-out Head were 

 prolonged on the strike to the south-east, they would overlie the 

 newer gneiss. 



Assynt. 



The section on which Murchison placed chief reliance is the suc- 

 cession on the south-west slope of Cnoc an drein, above the church. 

 As I entirely differ in my reading, I submit a section of the ground 

 (fig. 2), in which I have carefully excluded hypothesis and have 

 simply inserted the facts observed. 



Fig. 2. — Section above Inclmadamff Church. 

 S.W. * I N.E. 



1 



L. Limestone. DL. Dark Limestone. F. Felsite. 



WL. White Limestone. Q. Quartzite. h Fault. 



