President's Address. 381 



Lower Cambrian terrane of North America. This dis- 

 covery fixed the Lower Cambrian ^ age of these strata, 

 which up to that time had been looked upon as Lower 

 Silurian. The discovery was soon followed up by Mr 

 Macconochie, who, in 1894, obtained a suite of fossils from 

 the Fucoid beds on Meall a Ghuibhais, near Kinlochewe, 

 also in Eoss-shire, which yielded several species of Olenellus, 

 one of which is very near to 0. Gilherti, the form which 

 characterises the zone in the Western States of America, as 

 well as other fossils of American type.^ Mr Macconochie 

 afterwards proved the presence of this fauna in these 

 beds from EriboU in Sutherland to Sleat in Skye. Up to 

 the time of the above-mentioned discoveries, the Durness 

 Limestone was considered to be of Silurian age, in accord- 

 ance with the determination in 1859, by Salter, of the fossils 

 found at Durness by C. W. Peach.^ In the same paper 

 Salter also pointed out the American facies of the fossils. 

 The study of the fossils gathered by the Geological Survey 

 from the Durness Limestone in 1883 and 1884 led to the 

 belief that they belong to a lower horizon than that 

 assigned to them by Salter. In 1888 Sir A. Ceikie showed, 

 by means of fossil evidence, that a set of marbles that occur 

 in the Strath district of Skye, and which had been looked 

 on as Liassic limestones altered by Tertiary plutonic masses, 

 are really inliers of Durness Limestone.'* During the pro- 

 gress of the G-eological Survey in Skye, further collections 

 of fossils were made from these strata, and in 1899 a list of 

 fossils gathered from these beds appeared in the " Summary 

 of Progress for 1898." ^ The list shows that many of the 

 forms are common to the limestones of Strath and two of 

 the subdivisions of these limestones at Durness, as well as 

 to certain rocks in Newfoundland. In the last-mentioned 

 region the rocks containing these forms have been shown by 



1 "The Olenellus Zone in the N.W. Highlands," Quart. Jour, Geol. Soc. 

 vol. xlviii. p. 227. 



2 Qicart. Jour. Geol. Soc, vol. li., 1894. 



* QuaH. Jour. Geol. Soc, vol. xi. pp. 374-381, 1899. 



* Quart. Jour. Geol. Soc, vol. xliv. p. 62, 1888. 



* Mem. Geol. Sur., "Samraary of Progress for 1898," p. 55, 1899. 



