NICOL SOUTHERN GRAMPIANS. 



187 



former quarry. To the south the shales rest on reddish greywacke, 

 intersected by a great dyke of basalt, from twenty-five to thirty 

 yards wide. It dips northwards at about 60° under the limestone, 

 and runs a little north of east by compass (E. 40°-45° N.), and 

 thus approximately parallel to other similar dykes in the southern 



Fig. 4. — Section at Leny Old Lime-quarry, 



N.W. 



S.E. 



A 



A< 



x. Felspar-porphyry. 



a 2 . Ked shales. 



a x . Grey talcose shales. 



b. Limestone. 



c. Black shales. 



Grampians. It continues east as far as the Keltie, but seems dis- 

 tinct from the dyke noticed in the Pass. The limestone has also 

 been sought in vain in the low ground, as the quarries opened high 

 on the mountains are very inconvenient. Though of considerable 

 thickness and divided into many beds, this limestone, as is frequently 

 seen in the primary strata, is a very partial formation. The red 

 porphyry, hitherto overlooked, has produced considerable disturbance 

 in the strata, as shown both by the irregular outcrop of the limestone 

 and its relation to the other strata. Both the texture and colour of 

 the limestone, and the black carbonaceous-looking shales associated 

 with it, remind us rather of the Carboniferous formations than of a 

 primary deposit*. 



8. Ben Ledi — The great mountain of Ben Ledi, on the west side 

 of Loch Lubnaig, also shows an interesting section of these deposits 

 (fig. 5). 



At the foot of the hill, immediately north of the road to the Tros- 

 sachs, a mass of coarse conglomerate rises into a rugged knob. Be- 

 yond it the slope of the hill is low, and thickly covered with moss and 

 vegetation concealing the rocks. Where the acclivity becomes steeper, 

 a fine hard greywacke dips at 50° to N. 4° E., followed on the first 

 shoulder of the mountain by a light greyish-green clay-slate, contain- 

 ing grains of quartz and scales of mica, dipping at 40° to N. 2° E. The 

 next shoulder of the hill consists of light-grey mica-slate, dipping at 

 50° to N". 15° W. along the foliation, but with other very distinct 



* Prof. Harkness, in his section of this place, omits both the trap and por- 

 phyry. He also states that the limestone rests on quartz -rock, which I could 

 not find either in the quarries or the neighbouring ravines. The only rock at all 

 resembling quartz-rock is the porphyry above the limestone. 



