DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 25 



geology of the British Isles has probably never been adequately acknowledged. For 

 this want of due recognition the author himself was no doubt in some measure to blame. 

 He refers distinctly enough to various previous writers, notably to Jameson and 

 Macculloch, but he modestly mingles the results of his own personal examinations with 

 theirs in such a way that it is hardly possible to ascertain what portions are the outcome 

 of his own original observations. Less credit has accordingly been given to him than he 

 could fairly have claimed for solid additions to the subjects of which he treated. In the 

 later years of his life, I had opportunities of learning personally from him how extensive 

 had been his early peregrinations in Scotland, and how vivid were the recollections which, 

 after the lapse of half a century, he still retained of them. Judged simply as a well-ordered 

 summary of all the known facts regarding the geology of Scotland, his Essai must be 

 regarded as a work of very great value. Especially important is his arrangement of the 

 volcanic phenomena of Scotland, which stands far in advance of anything of the kind 

 previously attempted. Under the head of the " Terrain Volcanique," he treats of the 

 basaltic formations, distinguishing them as sheets {nappes, coulees) and dykes ; and of 

 the felspathic or trachytic formations which he subdivides into phonolites, trachytes, 

 porphyries (forming mountains and also sheets), and felspathic or trachytic dykes. In 

 the details supplied under each of these sections he gives facts and deductions which 

 were obviously the result of his own independent examination of the ground, and he 

 likewise marshals the data accumulated by Jameson, Macculloch, and others in such a 

 way as to present a comprehensive and definite picture of the volcanic phenomena of 

 Scotland such as no previous writer had ventured to give. 



L. A. Neckee, as the grandson of the illustrious De Saussure, had strong claims on 

 the friendly assistance of the Edinburgh School of Geology when he went thither in 1806, 

 at the age of twenty, to prosecute his studies. He was equally well received by the 

 Plutonists and Neptunists, and devoted much time to the exploration of the geology, not 

 only of the Lowlands, but of the Highlands and the Inner Hebrides. Most of his 

 observations appear to have been made in the year 1807, but it was not until fourteen 

 years afterwards that he published his Voyage en Ecosse et aux lies Hebrides/''' The 

 geological part of this work must be admitted to be somewhat disappointing. The 

 author's caution not to commit himself to either side of the geological controversy then 

 waging, makes his descriptions and explanations rather colourless. He adds little to what 

 was previously known, and even as regards the true volcanic origin of the basalts of 

 the Western Islands he could not make up his mind, contenting himself by referring 

 them to "the trappean formation." But these islands had so fascinated him that 

 eventually he returned to them as his adopted home, passed the last twenty years 

 of his life among them, and died and was buried there. Besides his Voyage, he 

 published in French an account of the dykes of the Island of Arran which appeared 

 in vol. xiv. of the Transactions of this Society. 



* See biographical notice of L. A. Necker, by Principal J. D. Forbes, Proc. Boy. Soc. Edin., v. (1862) p. 53. 



