﻿1861.] MT7RCHISS0N AND GEIKIE HIGHLANDS. 219 



and the rocks are consequently for long distances obscured. As we 

 approach Luib the dip appears on the whole north-easterly. There 

 the beds seem undulating along an E.JST.E. axis ; but they may pos- 

 sibly be reversed to N.W. Near Luib we saw no rock decidedly in 

 place ; but some exposed ledges appeared to have a N.W. dip. 



To the north-east of Luib, limestone has been worked on both 

 sides of the glen. The seam appears to run along the north-west 

 side, and is at present quarried on the declivity a short way west of 

 Killin. Below the limestone in the bed of the river, flagstones are 

 seen nearly horizontal, evidently the beginning of the quartzose series. 



Thus from Tyndrum to TCillin we cross obliquely a synclinal 

 trough of the schists with limestone at either side, below which lie 

 the quartzose flagstones. This trough extends north-eastward by 

 Ben Lawers and Strath Tummel to the head of Glenshee, whence it 

 appears to enter the Grampians. To the south-east it is prolonged 

 by the head of Loch Eyne to the Atlantic at Loch Swene. 



Loch Tay*. — This magnificent sheet of water occupies the line 

 of another anticlinal arch. The limestone just referred to as occur- 

 ring to the west of Killin, sweeps along the north-west side of the 

 lake, and plunges below Ben Lawers. In reality there are several 

 limestones here, as there are at Loch Awe ; but we did not stay 

 to note the details, being satisfied that the whole formed a calca- 

 reous group above the flagstones and below the schists. On the 

 south-east side of Loch Tay the limestones also occur, having a 

 south-easterly dip, and passing under the schists, which here, as at 

 Tyndrum, contain the well-known metalliferous veins worked by the 

 Marquis of Breadalbanef. 



"We are not aware -how far the limestones stretch towards the 

 south-west. Those of Loch-Earn-Head appear to belong to another 

 arch. Towards the north-east of Loch Tay they are soon lost, but 

 reappear in the valley of the Tummel at Pitlochrie. 



The numerous sections along the side of Loch Tay afford ample 

 scope for working out the details of this region. There is no more 

 beautiful district in Scotland, nor, at the same time, one where the 

 geologist might better acquaint himself with the order of super- 

 position, lithological characters, and mineralogieal riches of the 

 younger portion of the crystalline rocks of the Highlands. 



Loch Tay to Glen Lyon. — This traverse of the mountain-ridge of 

 Ben Lawers need not be detailed. It shows the limestones of Loch 

 Tay plunging below the schists of the ridge, which are often crumpled 

 and contorted. On the north-west side the dip changes to south- 



* It gives us great satisfaction to state that before entering upon our labours 

 of the last summer, Professor Harkness had the kindness to furnish us with 

 coloured sections made by him during an earlier part of the same year, of part 

 of the country to the south-east of the line of the Caledonian Canal. His re- 

 searches were, we found, in complete harmony with our own ; and his section of 

 Ben Lawers especially was of great use to us. He has since further extended 

 his observations into the North of Ireland, and found there the same order of 

 succession among the crystalline rocks, as will shortly appear in a paper com- 

 municated by him to the Society. 



t See Quart. Journ. Geol. Soc. vol. xvi. p. 421, &c. 



