October. 1910. 



KNOWLEDGE. 



413 



OSTRICH F.AKMIXG.— In an interesting paper on the 

 possibilities of ostrich fanning in the Transvaal (Trans. Agnc. 

 Joitrn. . ]u\y, 1910). Mr. E. Thornton, the Govenniient Expert, 

 throws out the suggestion of a Government experimental 

 farm, where both good and common birds should be kept, the 

 former to be used for paying the expenses of the farm, and 

 the latter for experimental purposes. One of the advantages 

 of such a farm, he suggests, would be to test the certain 

 poisonous weeds which have proved fatal to cattle and small 

 stock. Standard types of feathers should also be made and 

 loaned to the farmers. There would seem to be great future 

 possibilities in South .Africa for such an e.xperimental farm in 

 connection with w hat is a profitable industry. 



GEOLOGY. 



By G. W. TVRREI.L. .\.K.C.S.. F.G.S. 



THE GEOLOGICAL SLRM^V. SCOTL.AND. — The 

 Annual Summary of Progress of the Geological Survey for 

 1909. just issued, contains some interesting matter, especially 

 in regard to Scottish igneous and economic geology. The 

 structure of Ben Nevis is dealt with by Mr. H. B. Maufe in an 

 appendix. The detailed mapping of the district has brought 

 out the fact that the lavas of the summit rest on schists and 

 not on granite. The schists, however, have been almost 

 entirely concealed from view by the uprise of the granite. 

 The latter is shown to be composed of two distinct intrusions, 

 an older porphyritic granite forming an outer ring, and a 

 central plug of fine-grained biotite granite, intrusive in the 

 former, and with a perpendicular junction against the lavas 

 and basement schist. It is shown that the structure in this 

 area admits of a similar interpretation to that of the Glen Coe 

 caldera. 



Mr. C. T. Clough has examined the evidence for an 

 unconformity between the L'pper Carboniferous Red Barren 

 Measures and the Productive Coal Measures in the West of 

 Scotland, and has come to the important conclusion that it 

 does not justify a stratigraphical break between these 

 formations. Consequenth-. wherever the Red Barren Measures 

 appear at the surface, the Productive Coal Measures may be 

 expected below them. 



THE GEOLOGICAL SURVEY, E.NGLAM). — For 

 England and Wales we ha\e the announcements that the 

 survey of the South Wales Coalfield has been completed, and 

 that, in the Xottinghamshire and Derbyshire Field, a junction 

 has been effected with the work on the six-inch scale carried 

 out long ago in Yorkshire by the late Professor Green. We 

 are also informed that the survey of the Southern District 

 Devon and Cornwall) has been completed as far as con- 

 templated at present. A number of small inliers of Devonian 

 rocks, brought up by folding and faulting, have been found in 

 the Culm Measures to the west of Dartmoor. Interesting 

 observations ha\e also been made on the celebrated granite 

 mass of this area. The general slope of the original upper 

 surface of the granite, as shown by the remains of the 

 sedimentary co\er, is \'ery low, varying from twenty-three to 

 thirty-two degrees. This accounts for the fact that the 

 metamorphic aureole attains the great width of nearly four 

 miles in the neighbourhood of Peter Ta\y and Mar\' Tavy. 



THE X.A.TURAL CLASSIFICAl ION OF IGNEOUS 

 ROCKS. — Under this title an important paper by Dr. Whitman 

 Cross appears in the Quarterly Journal for August. Dr. 

 Cross is one of the authors of the Quantitative Classification, 

 proposed by four eminent American petrologists some 3'ears 

 ago. This system, based on arithmetical relations between 

 the quantities of certain standard minerals into which the 

 analysis of a rock is calculated, is not " natural," in the sense 

 that its divisions are arbitrary and do not coincide with any 

 natural lines of cleavage in the rocks themselves. Dr. Cross 

 contends that a natural classification is improbable, if not 

 impossible, because all the important characters of igneous 

 rocks, the products of complex geological conditions, are more 

 or less gradational — that no natural boundaries between rocks 

 really exist in nature. He passes under review the possibilities 



of natural classifications based on chemical composition, 

 magmatic differentiation, eutectics, mineral composition, and 

 rock-texture, and finds that no one of these factors gives rise 

 to divisions upon which to base a final petrographic sj-stem. 

 •A logical classification must therefore be based on the 

 quantitative development of fund.imental characters, and the 

 divisions of the scheme must have sharp artificial boundaries. 

 .A reply is made to certain criticisms of the Quantitative 

 System which is the outcome of these ideas. 



THE BRITISH ASSOCIATION. — Geologists in the 

 British .Association this year were fortunate in having as 

 President of the Association such an eminent geologist as 

 Dr. T. G. Boiiney. It is necessary to go back eighteen years 

 to the meeting at Edinburgh under the presidency of Sir 

 .Archibald -Geikie, to find the last time the .Association was 

 headed by a geologist. In his Presidential .Address Dr. 

 Bonney discussed some aspects of the glacial history of 

 Western Europe, especially in relation to the .Alps, upon 

 which, by his extensive travels and researches, he is eminently 

 qualified to speak. One school of glacialists claimed for 

 glaciers a very large share in the sculpture of the Alps. The 

 other school contended that the action of glaciers was abrasive 

 rather than erosive, and that, whilst rock basins might be 

 hollowed out under special circumstances, the sculpture of 

 ridges, crags, and valleys was mainly accomplished by the 

 ordinary agencies of running water and atmospheric denuda- 

 tion, and only slightly modified by the subsequent action of 

 ice. Dr. Bonney made no secret of his preference for the 

 latter view, whilst recogniEing the importance of recent work 

 tending to support the rival view of the erosive power of 

 glaciers. 



THE BRITISH ASSOCIATION. REPORTS OF 

 GEOLOGICAL COMMITTEES.— The Committee on the 

 Excavation of Critical Sections in the Palaeozoic Rocks of 

 Wales and the West of England report that during 1909 

 excavations were made in the Cambrian of Comley, Shropshire. 

 .A vertical section of the Comley Sandstone Series has now 

 been constructed from the information obtained during the 

 excavations of 1907-1909. In the Report of the Connnittee on 

 the Faunal Succession in the Lower Carboniferous (.Avonian) 

 of the British Isles. Dr. \'aughan describes the results of his 

 correlation of the Dinantian of Belgium with the Avonian of 

 Britain. A brave attempt is made by a Committee, under 

 the chairmanship of Prof. J. W. Gregory, to straighten out the 

 terminological tangle of South .African stratigraphy, but as 

 shown in the table of voting (.Appendix I), local geologists 

 have by no means arrived at unanimity. The end of the 

 labours of the Committee on the Composition and Origin of 

 the Crystalline Rocks of .Anglesey, the fifth report of which is 

 presented, is now within sight. We are promised a map this 

 autumn, and later, a descriptive memoir. The detailed work 

 of Mr. C. I. Gardiner and Prof. S. H. Reynolds on the 

 Sihu'ian Areas of Cos. Mayo and Galway continues. A 

 memoir on the Glensaul area has been published, and work is 

 now proceeding on the rocks of the Kilbride Peninsula (Loch 

 Nafooey area). Much good w-ork seems to have been 

 accomplished by the committees during the past year. 



METEOROLOGY. 



By John .A. Cirtis. F.R.Met.Soc. 



THE WEATHER for the week ended August 20th was warm 

 but unsettled. Temperature was above the normal every- 

 where, but rain was also in excess in all parts except the East 

 and South-East of England, while Sunshine was about the 

 average. Thunderstorms were experienced on the 14th, 15th, 

 and 15th, those of the 15th being widely spread, and strong 

 winds were felt in many places towards the end of the week. 

 While the average temperatures were high, the extremes were 

 not excessive, the highest reported being 79° in Guernsey, but 

 in Scotland N., and in Ireland N.. the maximum did not 

 exceed 69°. The lowest shade minimum was 42° at 

 Marlborough. 



