L, A. Necker de Saussure Vot/age en Ecosse. I95 



mountains to the liorth of this valley, the latter in thos« to the 

 south. The limit between this last formation and that of the 

 schistous chlorite is less distinct, but it mav be placed approxi- 

 matively on a line directed from S.W. to N.E., bednnine at 

 larbet on the western coast, passing along the south side of 

 Loch-Fine, through Glen-Dochart, Loch-Tay, to Killicrankie 

 and thence proceeding towards a point between Stonehaven and 

 Aberdeen, on the eastern coast, where it terminates. Mr 

 iNecker doubts whether the fundamental granite of Werner be 

 visible in Scotland. The gneiss shews itself well characterized 

 only in the most ancient parts of the formation, which by in 

 specting a map, we shall find, on the above principles of general 

 direction of strata, must be in the Hebridian Isles, where the 

 three elements of that rock are in nearly equal proportion On 

 the mainland, on approaching the mica-schists, the feldspar di- 

 minishes, the mica augments, and the rock assumes a more 

 toliated structure. Serpentine, amphibolite, diabase, primitive 

 imestoue, mica-schist, a species of clay-slate, and euphotide. 

 (gabbro of the Italians and Von Buch,) form subordinate beds 

 in the gneiss. Of all these subordinate beds none plays a 

 greater part in this formation than the quartz rock, whether 

 compact or granular, sometimes pure, sometimes mixed with 

 niica, and occasionally with feldspar ; the quartz rock is so 

 abundant in this district, that it constitutes by itself nearly the 

 country of Assynt and Groinard, on the north-Avest coast of 

 ^Gotland, forming mountains which are nearly 3,000 feet hio-h 

 Its vertical beds resisting decomposition much more than The 

 gneiss, present intheirhigh summits the forms of towers, needles 

 peaks, and sharp ridges, which resemble the protogine of the' 

 bavoy Alps. .Mr. Necker conceives that Dr. Mac Culloch 

 should have ranked his primitive red standstones with quartz 

 rocks, and he refers, in justification of this criticism, to M de 

 Saussure, Brochant, and d'Aubuisson. The formation of gneiss 

 is characterized by a great abundance of granitic veins, which 

 intersect the strata in different directions, and vary infinitely 

 in length and thickness. The only district in this formation 

 which has hitherto presented metallic veins is at Strontian In 

 the viica-schist formation are placed the highest mountains of 

 Scotland, occasionally rising to 3,600 feet. 



The formation of schistous chlorite, or chlorite slate, which 

 term Mr. Necker substitutes for clay slate, has subordinate 

 rocks very distinct from those contained by the older forma- 

 tions. Such are those mixtures of feldspar, quartz, and talc, or 

 chlorite, which according to the greater or less developement 

 ot crystallization, assume so many difl^erent aspects, but which, 

 however, should all come under the denomination oiprotocjine. 

 Ihe breadth of the stripe of ground occupied by this forma- 

 tion 18 not very considerable. It extends from the line indi- 



