286 Walk from Castleton 



mendous precipice, from which are seen the stupendous walls of 

 conglomerate, that bound this part of the water of Ardle. In 

 the conglomerate we observed large masses and veins of amyg- 

 daloid ; but here, as at Blair-Growrie, the predominating masses 

 are of porphyry. 



We now turned westwards and visited Forneth, the seat of 

 the Very Rev. Principal Baird, delightfully situated on the side 

 of the Loch of Clunie. In this route we passed several lakes, 

 on the banks of which we observed shell-marl of various inte- 

 resting kinds, and also different species of lacustrine shells. 

 The strata are conglomerate and old red sandstone^ ranging 

 NE. and SW., as is the case with the clay-slate on which these 

 deposites rest. To the south of Forneth, we visited the lime- 

 stone quarries of Gourdie, which are particularly interesting on 

 account of the change of the compact limestone into granular, by 

 the action of the trap-rocks which are intermingled with it. 

 From these quarries we walked to the Craig of Clunie^ which 

 we found to be the outgoing of a great mass of trap, in some 

 parts greenstone, in others porphyritic. It is said to be about 

 600 feet high. It rises through the red sandstone, and pro- 

 bably is disposed partly as a vein, partly as a bed. To the west- 

 ward of this Plutonian mass, on the property of Sir Alexander 

 Muir Mackenzie of Delvin, we observed in the red sandstone a 

 conglomerated limestone, resembling some varieties met with in 

 the red sandstone at the bottom of the Mid-Lothian coal-field. 

 From this point to the Craig of Stcnton, on the river Tay, 

 some miles below Dunkeld, the red sandstone and conglomerate 

 were the prevailing rocks. The Craig of Stenton is a Plutonian 

 mass, resembling that of the Craig of Clunie. Near the Craig 

 we examined some beds of conglomerate, in which the porphyry 

 is still the predominating rock. From this we went on towards 

 Caputli, where we crossed the Tay by a boat ferry, and at 

 some distance visited Gilly-hurn sandstone quarry. The sand- 

 stone is of a grey colour, horizontally stratified, and the strata 

 from two to six feet thick. The bridge at Dunkeld is built of this 

 sandstone. We next visited the Linn of Campsie. Here the 

 river Tay forces its way through and over rocks of a vein of ba- 

 saltic greenstone. Direction of the vein E. and W. It is ] 4 

 feet wide, and cuts across strata of red sandstone. It appears 



