92 



NA TURE 



[NOVEMBER 23, 1905 



below the Victoria Falls, from which he had just returned. 

 .Mr. Lamplugh, who penetrated down stream tor a distance 

 .if 71. miles from the halls, accepts and confirms the ex- 

 planation given by Mr. Molyneux, of Bulawayo, who 

 attributes the zigzags to the guidance of the stream-erosion 

 by transverse joints in the basalt plateau through which 

 tlie gorge has been cut. 



Prof. Penck read a paper, illustrated by a fine series 

 of lantern slides, on the Glacial deposits of the Alps. 



Mr. Kynaston, director of the Geological Survey of the 

 Transvaal, gave an account of the recent work of the 

 survey. Since its re-organisation in 1003, the attention of 

 the survey has been chiefly occupied with the later form- 

 ations forming the central portion of the country, and the 

 results obtained bear testimony to the able way in which 

 the work has been carried on. The igneous complex of 

 the Bushveld to the north of Pretoria may be mentioned 

 as forming an interesting petrographical province. It 

 illustrates the differentiation of a magma, in what is 

 probably an enormous laccolite, intruded between the 

 Pretoria and Waterberg series, into zones of increasing 

 basicity, ranging from the red granite of the central region 

 to the norites, pyroxenites, serpentine, and magnetite- 

 rock of the margin. 



Dr. F. H. Hatch explained the views arrived at by Dr. 

 Corstorphine and himself as to the correlation between 

 the pre-Karroo beds of the Transvaal and those of Cape 

 Colony (" Geology of South Africa," 1905). Dr. Hatch 

 also exhibited an instrument, devised by Mr. Oehmen, for 

 surveying bore-holes, that is, for determining the amount 

 and direction of the inclination of the bore-hole to the 

 vertical at any given depth — a problem of considerable 

 importance in a country where diamond drilling is so 

 largely used as in South Africa, as a deep bore-hole 111. i\ 

 deviate as much as 30 or more in its lower levels. 



The Rev. S. S. Dornan gave an account of his observ- 

 ations on the geology of Basutoland. The rocks belong to 

 the Stormberg series, and consist of sandstones, mud- 

 stones, and shales forming the Molteno Beds and the over- 

 lying " Red Beds." Fossils are rare, but a few plant and 

 reptile remains have been found in the former. Above the 

 Red Beds lies the Cave Sandstone, a thick-bedded sand- 

 stone, which forms the crests of the hills and contains 

 caves sometimes showing Bushman paintings. Reptile 

 tracks are frequent, but few other fossils occur. The 

 higher ridges of the Drakensberg and Maluti ranges are 

 formed of lava-flows and intrusive sheets belonging to 

 the volcanic series. This communication was of special 

 interest on account of the difficulty of making observations 

 and collecting fossils in Basutoland, as it is a native 

 reserve, and the natives are unwilling to allow any pro- 

 specting, fearing lest they might lose their country should 

 gold be discovered. 



On the last day of the meeting Mr. C. B. Horwood 

 read a description of the Dolomite formation, which is 

 important as being practically the only source of under- 

 ground water supply in the Transvaal. The rock is prob- 

 ably a deep-sea deposit, which has subsequently undergone 

 dolomitisation in shallow water, and has lost in the process 

 all trace of organic remains, so that its age is unknown. 

 Mr. W. Anderson contributed a paper describing the first 

 Tertiary rocks of marine origin which have been dis- 

 covered in South Africa. These comprise sands, marls, 

 and shales, with marine Mollusca (identified as probably 

 of Eocene age) and Foraminifera in the upper beds, while 

 in the lowermost shales occur numerous isolated bones of 

 Mammalia (elephant, rhinoceros, hippopotamus, &c), with 

 water-worn fragments of fossil wood, and fish and crus- 

 tacean remains. The beds, which are confined to the coast 

 of Natal and Zululand, are probably of estuarine origin. A 

 calcareous grit, forming the Bluff at Durban, is also 

 probably Tertiary in age. 



A paper by Mr. E. T. Mellor dealt with the evidences 

 in the Transvaal ol glacial conditions in Permo-Carbon- 

 iferous times, and the distribution of the glacial con- 

 glomerates forming the base of the Karroo svstem, which 

 corresponds to the Dwyka conglomerate of Cape Colonv. 

 Here, as in the country to the south, the striations, as 

 well as the nature of the boulders, point to a northerlv 

 origin. Mr. Lamplugh read a note on the occurrence of 

 Dwyka conglomerate at Kimberley Mine. 



NO. 1882, VOL. 73] 



In a paper on the diamond pipes and fissures 1 1 South 

 Africa, Mi. II. S. Harger expressed his view that the 

 source of the diamond lay in a zone of ultra-basic rocks 

 eclogites, lherzolites, and pyroxenites — in which it may 

 In- an original constituent crystallising from the magma, 

 for it has been frequently found in garnet- and more 

 rarely in olivine, and has been produced artificially in 

 thi' latter. The blue ground filling the diamond pipes and 

 the associated fissures is an altered breccia formed by the 

 shattering of these ultra-basic diamondiferous rocks during 

 a period ol volcanii activity, probably in late Triassic or 

 Jurassic times. Mr. Harger's paper was especiallj valu- 

 able as embodying the results of careful personal observ- 

 ations carried on through several years on the occurrence 

 and associations of the diamond in the numerous mines 

 scattered up and down the country, some of which are 

 little known outside South Africa. An interesting collec- 

 tion ol specimens of the associated minerals was on ex- 

 hibition in the adjoining museum. 



Papers were also communicated to the meeting by Dr. 

 J. T. Carrick, on the geology of the West Rand; bj Mr. 

 F. P. Mennell, on the plutonic rocks and their relations 

 to tlie crystalline schists; and by Mr. E. Heneage, on a 

 consideration of the Archaean period of North America 

 ,wv\ South Africa with reference to mineral occurrences. 



Apart from the papers read, a more than usual amount 

 of interest attached this year to the geological excursions, 

 of which a large and' most interesting series were 

 organised bj Dr. Mi lengraaff, Prof. R. B. Young, and 

 Mr. Rogers, to whom, with the other gentlemen wl ■>• ted 

 as leaders, the thanks of the section are especiallj due. 



These excursions -many ol which occupied several days 

 and were on a scale hitherto unprecedented, except 

 possibly at the Toronto meeting in 1897 — afforded the 

 members of the Geological Section a unique opportunity 

 ot seeing the most interesting features of the country 

 under the guidance of the men bj whom they had been 

 investigated, members id the various surveys be in" -pared 

 for the purpose by their respective Governments. 



After the nice line at Cape Town Mr. Rogers led a party- 

 through the Karroo, visiting, among much else of interest, 

 the folded ranges of the Ilex River district, and exposures 

 of the Dwyka conglomerate (or Boulder-clay) and of the 

 Beaufort beds which have yielded Pareiasaurus and other 

 characteristic reptiles. While' in Natal, several members 

 visited the glaciated surfaces .oil overlying beds at 

 Vryheid, under the guidance ol Mr. W. Anderson, the 

 Government geologist, and Dr. Me lengraaff, formerly State 

 geologist of tin- Transvaal. During the- meeting in 

 Johannesburg a number of afternoon excursions were made 

 to the gold mines and other points of interest, while after 

 its conclusion several more extended expeditions took 

 place. These included one to Vereeniging, under Dr. 

 Hatch, tu examine the sandstones and coal-seams of the 

 Ecca series, which have yielded the Glossopteris flora, and 

 the ass,,, iated beds, and to see Mr. T. N. Leslie's collections 

 of fossil plants from the Ecca sandstone and of flint imple- 

 ments from the Vaal River. Another party had an oppor- 

 tunity of studying the norites and syenites of the Plutonic 

 complex of the Bushveld, at the Pyramids and in the 

 neighbourhood of the Pienaar's River, to the math of 

 Pretoria, under Mr. Kynaston and Mr. A. L. Hall; while 

 a third party, with Mr. Hall and Mr. Frames, visited the 

 Duivels Kantoor, at the eastern edge of the Transvaal 

 plateau, where the escarpment of the Black Keel series 

 and Dolomite overlooks the floor of Archaean rocks, on the 

 denuded surface of which they rest unconformable. 



Excellent opportunities were also afforded of studying 

 the occurrence of the- diamond, both at the Premier and 

 other Transvaal mines, under Mr. Cullman, the chairman 

 of the Premier Diamond Company, and Messrs. Hall, 

 Harger, Kynaston, and Trevor, and at Kimberley through 

 the kind offices of Mr. Gardner Williams, the chairman of 

 lie Beers. 



In addition to this, there was a great deal of interest to 

 the student of surface geology to be seen during the long 

 train journey, among which may be mentioned the hill- 

 country in the north of Natat, the flat and sandy bush- 

 scenery along the line to the north, and the wonderful 

 examples eel weathering in the granite country of the 



Matopo Hills. 



