352 BATHYMETRICAL SURVEY OF 



the Farrar the general strike of the crystalline schists, with the 

 exception of local variations, is north-north-east and south-south- 

 west, or north-east and south-west that is to say, obliquely across 

 the course of the main valley. 



The basin of the Farrar is traversed by a powerful dislocation, which 

 .passes from the Conon valley in a south-west direction by Gleann 

 Chorainn and the head of the river Orrin, thence across Loch Monar 

 to the south-west shoulder of Riabhachan. It forms a well-marked 

 feature, and is accompanied by much brecciation and staining of the 

 rocks, as may be seen along its course to the north-east of Loch Monar. 

 At certain localities, parallel or branching faults, presumably con- 

 nected with the main dislocation, are met with, which modify to some 

 extent the surface features. 



During the period of confluent glaciers, the ice radiating from the 

 mass of high ground south of Loch Monar, embracing Sgurr na Lapaich 

 (3773 feet) and an Riabhachan (3696 feet), and from the heights 

 between that lake and Gleann Fhiodhaig to the north, flowed eastwards 

 down Glen Strath Farrar, and streamed northwards through some of 

 the passes towards the Orrin and Glen Fhiodhaig, and westwards in 

 the direction of the valley of the Ling. At a later stage it escaped 

 only by Strath Farrar. The diverging movement through the various 

 passes is indicated partly by ice-markings and partly by the disposition 

 of the moraines. 



Loch Monar is a true rock basin carved mainly out of the crystalline 

 schists of the Moine series, modified by the movements accompanying 

 the Strath Conon fault and its branches, to which reference has already 

 been made. The lip of the basin is now about half a mile below the 

 present outlet of the lake, the intervening area being silted up by the 

 alluvium brought down by Allt Coire na Faochaige a tributary which 

 joins the main stream opposite Monar Lodge. The rocks forming the 

 barrier of the lake are well seen in the gorge of the Garbh-uisge, where 

 they consist of massive siliceous Moine schists, intensely plicated along 

 vertical axes trending north-east and south-west. 



In the narrow part of the lake immediately above Monar Lodge 

 there is a small subsidiary basin, which may be accounted for by 

 inequalities in the hardness of the rocks, and by the irregular dis- 

 tribution of the drift on the west side of the loch. The deep part of 

 the main basin coincides with the belt of crushed strata accompanying 

 the Strath Conon fault that crosses the lake near Lub-an-Inbhir and 

 the parallel dislocation above Creag na h-Iolaire. A third fault, 

 trending east and west, enters the loch at the mouth of the Allt nan 

 Uan, which has produced considerable brecciation of the rocks. 



The shallow bar near the head of the loch is due to a spit of sand, 

 brought down partly by the Allt Riabhachan and partly by the stream 

 at Pait, which has been distributed by the action of the waves. 



