Reviews — The Work of the Geological Survey. 475 



to have been arrested by the influx of water into the workings, 

 although in one instance they evidently displayed some considerable 

 intelligence in draining a particularly good seam between Belmout 

 Hall and Ipstones by driving a level to carry off the mine water. 



3. The Summary of Progress for 1902 conveys an excellent idea 

 of the vitality of the Geological Survey, under its present able 

 Director, Mr. J. J. H. Teall, F.K.S., whose zealous activity in 

 planning the work is only equalled by the energy displayed by his 

 staff in carrying it into execution. 



In England and Wales the field-work has mainly covered four 

 areas — Devon and Cornwall, South Wales, the Midlands, and the 

 London district. In Scotland the work has been distributed over 

 six districts, four being in the unsurveyed portion of the Highlands 

 and two in the Carboniferous areas of the Midland Valley. In 

 Ireland the Drift Survey was continued in the neighbourhood of 

 Belfast. A few of the more important features of the work of tbe 

 year may be referred to here. 



Highland Metamorphic Bocks. — Probably the oldest rocks with 

 which the Survey has had to deal in the course of the year occur 

 in the Highland metamorphic region. Previous work in the areas 

 occupied by the Eastern Highland schists in the north of Scotland 

 have demonstrated the existence of extensive tracts of country 

 composed of rocks closely resembling certain portions of Lewisian 

 gneiss, especially those which occur in zones of secondary sheai'ing. 

 Those varieties of gneiss to which reference is made consist of 

 alternations of acid and basic material, with occasional lenticles 

 of ultra-basic rock ; but they differ from the unmodified gneisses 

 in possessing a granulitic structure. Two belts composed of rocks 

 of this type have been met with by Mr. Hinxman in Strathconan 

 Forest, Ross- shire, where they are seen to be most intimately 

 interfolded with siliceous granulites of the Moine type. Although 

 the exact meaning of these facts is not apparent, it may safely be 

 predicted that they will be found to have a most important bearing 

 on the origin of the Eastern Highland schists of Sutherland and Eoss. 



Other facts bearing upon the same subject have been observed 

 by Mr, Clough in central Ross-shire, a granitic rock at some early 

 period having been intruded into sediments which have been con- 

 verted into hornfels by contact-action. Zones of thrusting and 

 shearing comparable to those which have been described in the 

 Lewisian gneiss ti'averse both the granitic area and that occupied 

 by the altered sediments, the hornfels having, as a result, been 

 converted into mica-schists, and the granitic rocks into finely foliated 

 augen-gneisses, with a granulitic matrix. 



Important observations have been made in the Southern Highlands 

 by Dr. Peach and the officers acting under his direction, both on 

 the mainland and the islands of Argyllshire. 



The great quartzite formation of Islay and Jura, which has been 

 split up into several recognizable zones, in some of which flattened 

 worm-casts (nnnelide-burrows) occur, has been followed into Scarba, 

 and evidence obtained that the boulder-beds, so well developed in 



