MILLER NORTHERN HIGHLANDS. 583 



shape of a narrow belt about 3 feet wide extending in a straight 

 line from the bottom about two-thirds of the whole height upwards, 

 dipping to the east conformably with the enveloping body of gneiss. 

 In this section we have a well-marked example of a true limestone 

 apparently altered by heat, regularly interstratified with gneiss above 

 as well as below ; and to remove all doubt in the matter, large masses 

 of the limestone, loosened by the frost and rains, have fallen down and 

 can be seen beside the road, presenting the dull ashen appearance of 

 burnt shale just taken out of a furnace, from Craig na fielin the 

 limestone is continued along the eastern shore of Loch ErriboU 

 nearly to the mouth of the Eiver of Hope, dipping to the east and 

 overlaid by the gneiss and quartzites. In one of his memoirs Pro- 

 fessor Nicol says it can be traced northwards from the River of Hope 

 to Whiten Head ; and to satisfy myself on this point, I went by boat 

 to Whiten Head and coasted along the cliffs to the Eiver of Hope, but 

 failed to detect the limestone north of the Eiver of Hope. I do not 

 assert, however, that there is no limestone to be seen in that locality, 

 because the cliffs are high, attaining the elevation of 500 feet at 

 Whiten Head, and during spring tides (which was the case when I 

 visited it) it is dangerous to approach too near the cliffs, and I merely 

 leave it to future observers to describe the limestone of Whiten Head. 

 Central Gneiss of the North Highlands. — In one of his late me- 

 moirs on this subject. Sir Eoderick Murchison says that " this deposit, 

 from its junction with the sandstones and quartzites of the west 

 coast, rolls over the central districts of the North Highlands until it 

 meets the Devonian rocks of the east coast ; " and the description is a 

 most happy one. Prom the eastern shores of Loch ErriboU east- 

 ward to the Eiver of Strathy, and even to the centre of Caithness at 

 Dirlet Castle, the gneiss generally dips to the east or south-east, and 

 literally rolls over this wide extent of country (nearly 70 miles) 

 unchecked by any other formation ; and it can be seen passing under 

 and beyond the sandstones and conglomerates in the neighbourhood 

 of Tongue, at Ehi Tongue and Coldbackie, and other places, and 

 continuing its course eastward in one unbroken formation, at least 

 on the north coast, until it reaches the points just mentioned. I do 

 not mean that throughout this distance it always dips to the east, 

 because it often exhibits very fine examples of vertical strata, as in 

 the hill which the road ascends immediately after crossing the Eiver 

 of Borgie going eastward, and again at the parish church of Earr; 

 and wherever a hill of elevation occurs, there a western dip is gene- 

 rally visible as well as an eastern dip ; but, as a quarryman of the 

 district told me when I was examining the rocks, '^ All the quarries 

 in Lord Eeay's country work to the eastward," which was tanta- 

 mount to a declaration that all the rocks in the northern half of 

 Sutherland dip to the east, — as the quarrymen in this country foUow 

 the dip, their quarries being generally worked not far from the sur- 

 face ; and when we see the gneiss dipping to the east and overlaid 

 by the true Old Eed Sandstone or Devonian rocks, as proved by its 

 fossils, at Portskerray, Sandside, various places in the parish of Eeay, 

 Dirlet Castle, in the neighbourhood of the Ord of Caithness, and of 

 the Morven range of hills, we must admit that Sir Eoderick Mur- 



