554 



NATURE 



[February 23, 191 1 



to clear the way for an appreciation of the successive 

 faunas. The Lower Siwalik Beds, with Deinothermm 

 indicum and Tetrabelodon angustidens are classed as 

 Tortonian and Sarmatian ; the Middle Siwalik Beds, with 

 Mastodon, Stegodon, Hipparion, and Helladotherium, as 

 Pontian ; and the Upper Siwalik Beds, with Equus, Bos, 

 Elephas, and Sivatherium, as truly Pliocene. Mr. C. S. 

 Middlemiss (p. 206) revises the " Silurian-Trias sequence " 

 in Kashmir, in a paper covering a wide field. 



In the Quarterly Journal of the Geological Society of 

 London, vol. Ixvi., part iii., p. 420, Mr. J. B. Scrivenor 

 describes the relations of the igneous rocks of islands 

 between Johore and Singapore, and connects these rocks 

 successfully with types in Borneo and Amboyna. A 

 granite has caught up masses from a gabbroid magma, 

 while this magma has in turn invaded the consolidated 

 granite. The paper is important for those who have to 

 consider the question of segregation-patches as against 

 inclusions brought up from below. In a subsequent paper 

 {p. 435) Mr. Scrivenor describes a number of remarkable 

 rocks from the Kinta Valley of Perak, consisting of tour- 

 maline and corundum. These mostly contain carbon as a 

 separate constituent, and are " evidently derived from 

 certain beds forming part of a series overlying massive 

 beds of limestone." Residual structures remain in these 

 highh' altered rocks which strongly suggest oolitic grains. 

 The mineralisation is believed to have taken place during 

 extensive intrusions of granite in the district. Cassiterite 

 " frequently occurs in schists with which the tourmaline- 

 corundum rocks are associated." 



If Egypt, for geological purposes, may be included as a 

 British land, it should be mentioned that Dr. Hume, 

 the director of its Geological Survey, has published a 

 memoir on " The Building Stones of Cairo Neighbourhood 

 and Upper Egypt " (Survey Department Paper No. 16, 

 1910, price 150 mmes.). Maps of the quarry-areas are 

 given, with names in Arabic and English. Analyses of 

 many of the limestones are quoted, and their durability 

 and power of absorbing water are considered. Much of 

 the information was collected by the late Mr. T. Barron. 



Dr. Hume also states his views on " The Origin of the 

 Nile Valley in Egypt" (Geological Magazine, 1910, p. 385). 

 He believes that the dome-structure of the strata in the 

 Gulf of Suez has been cut across by notable fractures, of 

 which there is still more marked evidence in Sinai. But 

 the main structure of Egypt and of the Nile Valley lying 

 in it has been determined by folding and erosion rather 

 than by trough-faulting. Egypt is formed by a synclinal 

 following on the " wave-crest " that is revealed by the 

 Eastern Desert and Sinai. The Nile ravine follows the 

 axial line of the centre of the synclinal trough, and has 

 been assisted by the presence of easily eroded Cretaceous 

 and Middle Eocene strata. A transverse system of folds, 

 fairly east and west, is also traceable. The oases seem to 

 be due, in the first instance, to the main north and north- 

 west folding. 



The Cairo Scientific Journal for September, 1910, con- 

 tains a general review of the origin of petroleum, by Dr. 

 Hume, with special bearing on the Egyptian oil-area at 

 Gebel Zeit. The author inclines to the view that the 

 Egyptian oil is derived from animal matter included in 

 the deposits of a drying Mediterranean Sea, and points out 

 that the associated gypsum supports this theory. Major 

 H. de Lotbini^re (p. 221) shows how the clays in the Nile 

 Valley bear up the water now introduced by irrigation 

 into the overlying sands and the cracked clays of the 

 surface. This rise in the water-table, discussed by Mr. 

 Ferrar and others, is one of the newest agricultural 

 problems that Egypt has to face. 



South Africa continues to produce a wealth of geological 

 memoirs. The Transvaal Mines Department issues an 

 explanation of Sheets 5 and 6 of the large-scale geological 

 map, covering the country round Zeerust and Mafeking 

 (price 2S. 6d.). The Geological Commission of the Cape 

 of Good Hope has allowed the use of its map to complete 

 the Mafeking sheet drawn up by its neighbour. Messrs. 

 Hall and Humphrey, authors of the memoir, point out the 

 large part played by contact-metamorphism in the rocks 

 of the Pretoria series of the Transvaal system. The 

 Bushveld plutonic complex is held to be responsible for 

 the widespread production of slates with biotite, cordierite, 

 and andalusite. The gold-bearing quartz-reefs along the 

 NO. 2156, VOL. 85] 



Malmani River near Ottoshoop are reported on, and it is 

 suggested that work in them was abandoned when the 

 water-level in the adjacent dolomite was reached. Hill- 

 shading has been added to these maps, which is a great 

 improvement. It is doubtful, however, if the rivers on a 

 heavily coloured geological sheet should be shown in blue, 

 since it is always important to trace out their courses 

 at a glance. The geologists, moreover, are probably not 

 responsible for the choice of scale, which is provokingly J 

 near i cm. to i mile, but still nearer 3 inches to 7 miles. ■ 

 This is a heart-rending thing to work with, whether miles 

 or kilometres are familiar to one's mind. 



Mr. A. L. Hall has written for the Transvaal Survey 

 an important memoir on the " Pilgrims' Rest Gold Mining 

 District " (1910, price 7s. 6d.), in which a large map of 

 the Lydenburg and Barberton districts is inserted. The 

 great escarpment of the Drakensberg, formed of the lowest 

 sandstones of the Transvaal system, runs from north to 

 south down the eastern part of the area, and the hill- 

 shading portrays for the first time the numerous immature 

 valleys dropping steeply from it to the broken granite 

 lands of Barberton. The Blyde River has an interesting 

 course, mainly on the Dolomite, past Pilgrims' Rest, 

 within and parallel with the escarpment, catching the first 

 waters on the dip-slope, and escaping finally over the edge 

 by a long notch in which the granite is exposed. Its 

 basin is clearly threatened by the recession of the great 

 escarpment. Westward, the beds of the Pretoria series, 

 above the Dolomite, come in, remaining almost level over 

 broad areas, as we reach the true plateau-land of the 

 Transvaal. The general fall of the country northward to 

 the Olifant's River is seen, however, in the parallel courses 

 of the streams, of which the Blyde River is the most 

 easterly, and their valleys give a rolling character to the 

 landscape. The important auriferous deposits of the area 

 consist mainly of quartz-reefs lying at definite horizons in 

 the Dolomite, with certain cross-reefs cutting across the 

 bedding. An area for future prospecting is indicated 

 towards the Olifant's River (p. 144). The handsome illus- 

 trations in this memoir will interest anyone who has stood 

 on the Drakensberg edge in eastern Transvaal, and has 

 seen the huge inland plains terminate suddenly against the 

 highland air. Yet here, as Prof. Penck has urged, it is 

 not necessary to invoke a fault to account for the rapid 

 fall towards the Indian Ocean. Folding and erosion, the 

 same processes that have given us our Chilterns and our 

 Cotteswolds, seem alone responsible for the impressive 

 margin of the veld. 



The Geological Commission of the Colony of the Cape 

 of Good Hope has published in 1910 Sheets 32 and 40 of 

 the map on the scale of i inch to 3-75 miles. Here, 

 again, the scale, i : 238,000, has a truly British and un- 

 compromising air. Sheet 32 has Van Wyk's Vlei near 

 its centre, where depressions occur on rocks of the Ecca 

 series, between flat-topped kopjes. The dolerites in the 

 Karroo system form characteristic ring-like outcrops. 

 Sheet 40, showing the country around Marydale, includes 

 the north-westerly stretch of the Orange River on the 

 edge of Griqua Land West. It is a very interesting map 

 for the student, as may be seen at once in the section at 

 its foot. The contrast of the old schists on the west, 

 invaded and almost eaten up by granite, with the un- 

 dulating beds of the Transvaal system on the east, is only 

 one of its many attractive features. 



We cannot do justice to the numerous papers in the 

 Transactions of the Geological Society of South Africa. 

 Prof. Schwarz (vol. xi., 1909, p. 107) points out the interest 

 of the occurrence of high Senonian or Danian beds (the 

 Alexandria formation) on the south coast of Africa. Their 

 age appears to be determined by Mr. W. D. Lang from 

 the pol3'zoa onl)s and they seem to have been deposited 

 near a shore. Their position implies an epoch of sub- 

 mergence after the elevatory movement that carried the 

 Lower Cretaceous Uitenhage beds to a height of 4000 feet 

 above the sea. The discussion on this paper will be found 

 in vol. xii., 1910, p. xxxv. Dr. Rogers here points out 

 that there may not be such a gap in the African Creta- 

 ceous as Prof. Schwarz suggests, if we regard the Pondo- 

 land beds as Senonian rather than Cenomanian. Mr. 

 Recknagel (vol. xi., p. 83) has. the advantage of describing 

 a new field in his paper on some mineral deposits in the 

 Rooiberg district, where tin-ore and tourmaline figure 



