June 24, 1897J 



NATURE 



179 



100 miles from the mouth of Loch Eriboll into Sleat in 

 Skye. Not only the bands of the Durness limestone, 

 but the "fucoid beds" and the marked subdivisions of 

 the underlying quartzite retain their general characters 

 throughout the whole extent of their outcrop. 



The mapping of the Isle of Man has now been com- 

 pleted by Mr. Lamplugh. Much information has been 

 obtained as to the structure of the " Skiddaw Slates " of 

 that island, but no further evidence has been found to 

 fix their true geological age. i 



The revision of the Silurian formations of the Southern 

 Uplands of Scotland has been brought to a close by 

 Messrs. Peach and Home, with the assistance of Mr. A. j 

 Macconochie. The whole complicated structure of that 

 extensive region has now been unravelled. Among the 

 more interesting recent additions made by these observers 

 to our knowledge of the ground, has been the wide de- 

 velopment of volcanic rocks associated with the Lower j 

 Silurian sediments. The chief interval of volcanic 

 activity seems to have been the Arenig period ; but last i 

 year evidence was met with of contemporaneous lavas 

 in the Bala series of Peebleshiie. In the Report some j 

 valuable details are supplied by Mr. Teall regarding the | 

 volcanic series of the Southern Uplands, and also the 

 Galloway granites with their apophyses and attendant 

 metamorphism. 



The Silurian areas of Ireland are likewise undergoing 

 revision, with the view of bringing the maps up to the pre- 

 sent state of knowledge on the subject. The whole of | 

 the country north of Dublin has now been completed by i 

 Messrs. Egan and McHenry ; while the fossil collector, j 

 Mr. Clark, has discovered many new localities for fossils j 

 in the Silurian rocks. The revision proceeds upon a 

 careful search for organic remains, alid the subdivisions 

 of the Silurian formations are based essentially on the 

 evidence of these remains. 



Some important modifications of previously published 

 views were obtained last year by Sir Archibald Geikie 

 and Mr. Kilroe in the west of South Mayo and North 

 Galway. Evidence was gathered which showed that the 

 volcanic rocks of that region, hitherto regarded as of 

 Upper Silurian age, undoubtedly belong to the lower 

 division of the system. 



In the Old Red Sandstone, the chief work accomplished 

 bv the Survey in 1896 lay in Ross-shire, Arran, and 

 .Argyllshire. In the first-named country two hitherto un- 

 known outliers of this formation, capping hills of schist, 

 were found by Mr. Gunn — striking monuments of the 

 denudation of that region. In Lome considerable pro- 

 gress has been made in the mapping of the interesting 

 volcanic series of the Old Red Sandstone, and some 

 suggestive observations have been made by Mr. Kynaston 

 as to the possible connection of the andesite lavas with 

 the granite of Ben Cruachan. 



Among the Carboniferous rocks, the chief task on 

 which the Survey is at present engaged is the revision 

 of the coal-fields on the scale of six inches to a mile. 

 Good progress is reported in the mapping of the great 

 coal-field of South Wales, and a beginning has now been 

 made with the publication of the re-survey. The new 

 maps cannot fail to be of great value in the future de- 

 velopment of the mineral resources of this important 

 region. In general, each coal-owner knows only his own 

 ground, and that often very imperfectly. No general 

 acquaintance with the structure and resources of the 

 whole coal-field can be obtained until all the scattered 

 observations at the different mines are correlated and 

 generalised. This, however, is a result which could 

 hardly be effected by private enterprise. It is essen- 

 tially a national undertaking, and it is this task on 

 which the Geological Survey is now engaged. Mr. 

 Strahan and his colleagues, who are charged with the 

 re-survey, are to be congratulated on the excellent maps 

 which they are producing. Not only are the Coal- 



NO, 1443, VOL. 56] 



measures receiving attention, but the surrounding older 

 formations, the mapping of which is required for the 

 completion of the sheets of the coal-field, are undergoing 

 careful examination, and have already yielded some 

 interesting new results. Thus Mr. Strahan last year dis- 

 covered that the igneous rocks, which have long been 

 supposed to be intrusive in the Carboniferous Limestone 

 of West Somerset, really include intercalated tuffs, 

 marking the sites of volcanic eruptions during Carbon- 

 iferous time in the south-west of England. 



Strata of Permian age are reported from the northern 

 end of the Isle of Man, where they have been detected 

 in some unsuccessful borings for coal. The younger red 

 sandstones of the Isle of Arran are regarded as not im- 

 probably belonging to the same geological system. 



Triassic and Rhaetic rocks have been mapped over 

 considerable tracts along the southern side of the South 

 Welsh coal-field, and some interesting data have been 

 obtained by Mr. Cantrill regarding the nature and origin 

 of the breccias lying at the local base of these formations 



The most important area of Jurassic rocks examined 

 last year lies in the district of Strath, in Skye, where 

 the ground was mapped by Mr. H. B. Woodward, wha 

 has traced the lithologicai and paheontological sub- 

 divisions of the Lower and Middle Lias. 



The Cretaceous system over considerable tracts of the 

 south of England was examined during the past year 

 for the purpose of mapping its subdivisions, the clear 

 delineation of which is now found to have so important 

 a bearing in questions of water-supply. Mr. Jukes 

 Browne is engaged on the preparation of a general 

 memoir on the Upper Cretaceous formations, and has 

 had much assistance from Mr. William Hill, whose ex- 

 tensive and accurate knowledge of the subject has been 

 placed at the service of the Survey. 



The field-work in the south of England during 1896 

 lay, for the most part, outside of the areas of the Ter- 

 tiary formations. Most of the mapping among rocks of 

 that series was carried on in the west of Scotland, where 

 so large and varied a development of Tertiary igneous 

 masses occurs. Mr. Harker continued his investigation 

 of the eruptive rocks of Skye, and contributes some 

 important facts to the Annual Report. Mr. Hinxman 

 noted two remarkable vents in Raasay, while Mr. Gunn 

 was successful in adding a number of previous unknown 

 particulars to our knowledge of the younger igneous 

 rocks of Arran. 



The Superficial Deposits, formerly entirely neglected,, 

 now receive a large share of the attention of the Geo- 

 logical Survey. As they thickly cover wide tracts of 

 country, they are of paramount importance in regard to- 

 agriculture, water-supply, drainage and many other ques- 

 tions of daily life. It is most desirable, therefore, that 

 their nature and limits should be accurately delineated 

 upon maps. This has been done by the Survey over the 

 whole of the northern half of England, and the same 

 investigation is now in progress in the southern half. 

 When the " Drift Survey," as it is called, is completed, 

 the British Isles will be in possession of a map which 

 will serve as an admirable guide to the farmer, well- 

 sinker, engineer, and generally to the whole of that wide 

 public that is practically interested in the relation of 

 the soils and subsoils to all kinds of sanitary questions. 



The Survey, while dealing with these applications ot 

 its work, does not lose sight of the intensely interesting 

 geological problems presented by the various superficial 

 formations. The present Report, like its predecessors,, 

 contains much fresh information on this subject. From 

 the cwms of South Wales to the downs of Kent, the 

 surveyors have been at work among the various drifts, 

 and the more important of their observations are sum- 

 marised by the Director-General. Of special interest 

 are Mr. Lamplugh's generalisations regarding the suc- 

 cessive stages in the history of the glaciation of the Isle 



