DEPOSITS OF ASSYNT.

343

visited, two years ago, the district near Whiton Head, in whichthe sections occur that are said most thoroughly to demon-strate this superiority of the gneiss to the quartz rock, butwas prevented from examining them by a tract of wet andvery boisterous weather. There seems, however, to be a linkwanting in the evidence, in its bearing on the matter speciallyin hand,—the position of the Assynt deposits. The gneissof the Moin,—a dreary waste, that stretches between LochEriboll and the Kyle of Tongue ,—does seem to overlie thequartz rock of Whiton Head, just as in many other localitiesgenuine gneiss holds, on the small scale, a superior position togenuine quartz rock; but it has perhaps still to be shownthat the quartz rock here is at all of the same age, or occu-pies relatively the same place, as that which in Assynt over-lies the calcareous flagstones, and forms the summit of BenMore. The nearest Red Sandstone to the gneiss and under-lying quartz rock of Whiton Head is that of Craig na "Vrechan,at Tongue ; and it very decidedly overlies the gneiss. Butthis special point I do not profess to have examined.

In conclusion let me remark, that while, from the reasonsadduced, I have been led to conclude that the sandstone de-posit of the west of Sutherland, with its associated quartzrock and limestone beds, represents the Lower Old Red Sand-stone of the eastern coast, I do not regard the conclusion asfounded on other than merely a strong probability. In specu-lating on the true place of a deposit in which fossils do notoccur, and whose stratigraphical relations to the well-knownfossiliferous rocks cannot be traced, we must, I suspect, becontent with simply the probable. For my own part, theoccurrence in one of the flagstones of Strongchrubie, of thespine of a Cheiracanthus, or of a few scales of Dipterus, orof the plates of a Coccosteus, would satisfy me more thoroughlythan all the arguments ever derived from mineralogical char-racter, or from the occurrence, in a certain order of certain