of the Scottish Highlands. 



215 



XI. Section across the Pass of Leny. 



The next section we propose to describe is one through the Pass 

 of Leny to the north of Callander, which is a particularly favourable 

 one for the study of the lower argillaceous and lower arenaceous 

 zones. The lowest rock seen in this section is our lower argillaceous 

 zone, which runs up immediately to the north of the Old Red 

 era 



Fig. 3. — Section across the Pass of Leny. 



e. Lower Arenaceous Zone. 



f . Lower Argillaceous Zone. 



g. Leny Limestone. 



Sandstone with an average dip of about 50° to the north-west. 

 It is mainly composed of fine greywackes, with beds of clay-slates, 

 and black graphitic schists, and is well seen in the lower gorge of the 

 Pass of Leny, both in the bed of the river and in cuttings along the 

 road. One of the most interesting sections of this series is to be 

 seen in the old limestone quarry. On the hills above the old 

 Kilmahog toll-house here, the limestone is exposed dipping to the 

 north-west at an angle of 50° ; the limestone is underlain by a series 

 of beds of black graphitic shales, while above it appears another 

 series of reddish slates, intruded into which we find a vein of quartz 

 felsite strings, and smaller beds of limestone are seen disseminated 

 through the slates. Upon the whole, these lower argillaceous beds 

 remind us wonderfully of the upper argillaceous series found on the 

 Ben Lawers and Craig Na Challeich ridge. The component rocks 

 are exactly the same in both. We find limestones, graphite slates, 

 and such fine argillaceous rocks as clay-slates and greywackes. The 

 rocks of the upper zone, as before observed, show evidence of more 

 extreme metamorphism than the lower, this probably being 

 accounted for by their higher position in the mountain mass, they 

 being consequently more liable to contortion and shearing than the 

 lower members, which would be simply pressed out or indurated. 

 The evidence on this point is not, however', very strong, and will 

 require further and more detailed investigation. Passing from the 

 lower and more argillaceous beds, and further north on the line of 

 section, the latter are seen to pass upwards into a more arenaceous 

 group marked by massive beds of grit, grey waeke, and conglomerate. 



