Eevicus — Geological Survey— Summary of Progress. 521 



petrographical departments during the past year. The record is one 

 which indeed reflects credit on the small band of enthusiastic workers 

 which compose the Survey. Their reports have been pieced together 

 by the Director General, who has himself contributed notes on the 

 Dalradian schists and Ohl Ked volcanic rocks near Oban, on the 

 volcanic rocks in the Carboniferous Series of Somerset, and on the 

 oUler rocks of Skye and Scalpa. 



It is hardly possible to do more than glance generally at the 

 contents of this detailed report. The subject-matter is arranged in 

 stratigrapbical order, beginning with the Pre-Cambrian rocks of 

 Koss-shire and continuing to the Peat-bogs of Ireland. Something 

 of interest will be found for all students and workers, in the 

 occurrence of minerals and fossils, in the discussions on schists and 

 rock-structures, in the accounts of volcanic and plutonic rocks, of 

 contact metamorphism, faults and foldings, in the descriptions of 

 new railway-cuttings, well-borings, and in the analyses of dolomites 

 and iron -ore. 



The accounts of the Pre-Cambrian rocks of Ross-shire contain 

 much that is interesting, while on some points further information 

 is desirable. Mr. Peach divides the rocks into two main groups — 

 (1) the Lewisian gneisses and (2) the Moine type of gneisses and 

 muscovite-biotite-schists. The Lewisian gneiss is supposed to be the 

 older, and is stated (p. 7) to have been " thrust forward among the 

 Moine schists," but there does not seem to be any clear evidence of 

 tliis, for a little further on he says " there seems to be a definite 

 order in at least the local succession," and the "Moine schists always 

 lie next to the older gneisses, while the centres of the synclines of 

 these schists are occupied by the muscovite-biotite gneiss." This does 

 not give the impression of a " thrust-plane" junction, and, indeed, it 

 is practically stated only a few lines further on that the junction is 

 an unconformity. If this is so, one would expect a pebbly base to the 

 Moines, but no mention of such a base occurs. Neither is there any 

 information as to the age of the crystallization of the two groups of 

 rocks, whether they are of the same age or not. An interesting 

 series of foliated granites is described on p. 9. 



Mr. Home, in the Fannich area, gives an account of several rock- 

 groups that he has been able to map out, which are a continuation of 

 those already mapped by Mr. Gunn. Five of these are mentioned in 

 " what appears to be descending Order." The remarkable part of 

 this sequence is that No. 1, or the highest, is stated to " resemble 

 certain types of Lewisian gneiss." The lowest. No. 5, is obviously 

 the same as the lower member of the Moine schist of Mr. Peach. 

 The difficulty with regard to No. 1 is recognized by Mr. Home, who 

 suggests two explanations of it, the first of which indicates a structure 

 similar to that of the Archasan gneiss of Loch Maree. We may also 

 note (p. 15) that No. 5, the most persistent type of the Moine 

 schists, was probably crystallized " prior to the Post-Cambrian 

 movements." 



Mr. T. I. Pocoek describes somewhat similar groups, but on p. 17 

 the following statement is made : — " The basic portions of the 



