Yol. 50.] ANNIVERSARY ADDRESS OF THE PRESIDENT. 87 



Group ' is probably nearer the mark. The subsequent discovery of 

 the Olenellus-zone in the ' Fucoid'-beds may perhaps induce Mr. Peach 

 to regard the Durness fauna as probably an Upper Cambrian one. 



We should now seek for a parallel to the Durness Limestone in 

 other parts of Scotland, outside the area technically known as the 

 North-west Highlands. This may be found, according to Sir 

 Archibald Geikie, in the Altered Limestone of Strath in Skye, 

 which had been regarded by great authorities as an instance of 

 contact-metamorphism in a rock of Liassic age. Many years ago 

 the Author expressed a suspicion that this rock might turn out to be 

 of the age of the Durness Limestone, and recent investigation has con- 

 vinced him that such is the case. In lithological characters the rock 

 differs from the Lias of the district, consisting in its lower part of 

 dark limestones full of black cherts, and comprising a higher group of 

 white limestone with little or no chert. Moreover, white quartzite 

 is found in association with the limestone at several places in 

 Strath ; also representatives of the well-known ' Fucoid '-beds at 

 Ord in Sleat. These latter strata form a persistent band which 

 may be traced from Sutherland into Skye. The palaeontologieal 

 evidence is also favourable. It would seem that the Lias rests upon 

 this Cambrian limestone unconformably, and actually contains at 

 its base a coarse breccia largely composed of pieces of the older 

 limestone akmg with fragments of chert and quartzite. The most 

 singular thing is that the metamorphism is stated to be confined to 

 the Cambrian limestone and to have been produced by large bosses 

 of granophyre (syenite) of Tertiary age. Mr. Marr considered that 

 the recognition of the Durness Limestone in Skye might be expected, 

 and referred to the Stinchar Limestone of the Girvan district as 

 being of the same age, viz., that of the Ort7iocer-as-limestone of 

 Sweden. 



A further advance has been made in the survey of the Cambrian 

 area of the North-west Highlands by the discovery of Olenellus in 

 the ' Fucoid '-beds and ' Serpulite '-grit of the Dundonnell Forest in 

 Ross-shire. Particulars are given by Messrs. Peach and Home in a 

 recent communication to the Society, wherein they comment upon the 

 remarkable persistence of the sub-zones already identified in Assynt 

 and at Loch Eriboll. The basal quartzites are, for the most part, 

 destitute of those worm-casts so characteristic of the overlying zone, 

 but in the Ben Eay forest, south of Loch Maree, certain dark grey 

 shales, which may probably yield organic remains at some future 

 time, occur near the base of the series. The five sub-zones in the 



92 



