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EECENT WORK Or THE GEOLOGICAL STTRVEY 



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Silurian zones from the basal quartzites 

 up to the limestone are repeated by 

 thrusts of more or less magnitude, till we 

 reach the maximum thrust which brings 

 in the green schists and sheared gneiss 

 with strips of highly altered quartzites. 

 These are overridden in turn by the 

 micaceous flagstones above the Moine 

 Thrust-plane. 



On the southern slope of Quinaig (fig. 

 13) the unconformability between the 

 quartzites and the Cambrian sandstones 

 is well exposed in the great escarpment 

 skirting Loch Assynt, the sandstones 

 being nearly flat, while the quartzites 

 are inclined to the E.S.E. at angles 

 varying from 15°-20°. Both zones are 

 succeeded by the " Fucoid-beds " and 

 Serpulite-grit in natural order ; but close 

 to the highroad leading to Kylesku the 

 strata are truncated by a major thrust- 

 plane, along which the "Fucoid-beds," 

 Serpulite-grit, and basal limestones have 

 been driven, repeated by numerous minor 

 thrusts. Generally the piled-up strata 

 belonging to these horizons are tilted at 

 high angles to the plane of the major 

 thrust. OwiDg to the extraordinary 

 number of these minor thrusts, there 

 are no fewer than thirteen outcrops of 

 the Serpulite-grit in the course of one 

 third of a mile. Close to Achumore 

 another powerful major thrust ushers in 

 the basal limestones, Ijing at gentle 

 angles and resting on the highly in- 

 clined thrust-strata just described. They 

 are repeated by numerous minor and 

 major thrusts, and thrown into a series 

 of arches and troughs, as shown in sec- 

 tion, till they are overridden by the 

 materials brought forward by the Glen- 

 coul Thrust-plane. The outcrop of this 

 thrust-plane has been traced con- 

 tinuously from the shore of Loch Glen- 

 coul, southwards by Loch na Gainmhich 

 along the base of the western slope of 

 Glasven, to the Poll an Droighinn burn, 

 thence by the base of Ben Fhuarain and 

 Coinne-mheall of Ben More, till it is 

 eventually overlapped by the Ben-More 



