April 2, 1903] 



NA TURE 



507 



serious work began. He starts at once (p. 19) with 

 the interesting- observation that the coarse auriferous 

 gravels near Sintang show that the carrying power 

 of the rivers was formerly greater ; and the explanation 

 is found in the greater height of the ranges of the 

 interior in late Cainozoic times. The author returns 

 to these deposits in his valuable geological summary 

 (pp. 453-9), where he states his conclusion that Borneo 

 has undergone continuous degradation, through atmo- 

 spheric action, in the Quaternary era. The products 

 of decav have encroached on what was in earlier times 

 a shallow sea, broadening the land, and connecting 

 island after island with the central mass by new deposits 

 of alluvium. At the same time, the alluvium has 

 accumulated on the decaying ranges, burying their 

 lower slopes in material which they themselves sup- 

 plied. In opposition to the elevation-theory of Pose- 

 witz, Molengraaff sees in the growth of the river- 

 deposits the real cause of the post-Pliocene extension 

 of Borneo. 



From Semitau, higher up the Kapoewas, the author 

 diverged through the thick forest, up a side-stream to 

 Mount Kenepai. This is a steep mass 1136 m. above 

 the sea, carved out of granite injected by andesite, the 

 granite (p. 432) being of post-Jurassic age. Still more 

 interesting igneous features are seen in the next range 

 visited, on the Mandai River, where huge horizontal 

 beds of volcanic tuff give rise to " table-mountains " 

 bounded by vertical rock-walls. Molengraaff (p. 65) 

 names this range the Muller Mountains, after the mur- 

 dered explorer Georg Muller, who is believed to have 

 penetrated the area. The volcanic action that here 

 poured out rhyolite and andesite and abundant tuffs 

 along an east-and-west line in Central Borneo was 

 probably post-Cretaceous (p. 441), and may have con- 

 tinued throughout Cainozoic times. The range is now 

 known to extend over at least 280 km., and has doubt- 

 less (p. 445) an important relation to the post-Cretaceous 

 movements of the land. Have we here, indeed, un- 

 expectedly revealed by Molengraaff, one of those 

 volcanic chains that accompany the Eurasian " Alpine " 

 svstem of folding? The author shows how the Muller 

 Mountains have been piled on sunken land (p. 44.s), 

 which has been lowered by east-and-west faults from 

 the south flank of the Upper Kapoewas range. This 

 old range, the slates of which are possibly of Palaeozoic 

 age, was at one time covered by Jurassic rocks, the age 

 of the latter being determined by Dr. Hinde's observa- 

 tions on the radiolaria. These rocks, now preserved by 

 the downward faulting in the lake-district north of 

 Semitau (pp. 123 and 414), are grouped by Molengraaff 

 as the " Danau formation." The faulting has affected 

 the " Eogene " sandstone strata, which once spread 

 across the folded Cretaceous and Danau systems, and 

 terminated somewhere on the flanks of the Upper 

 Kapoewas chain. The plain of the Upper Kapoewas 

 River was thus determined by the downthrow of the 

 Danau beds in Middle Cainozoic times, whereby the 

 chain of mountains to the north was more than ever em- 

 phasised. While intrusions of granite had already (p. 449) 

 accompanied the post-Jurassic and pre-Eocene move- 

 ments, the volcanic line of the Muller Mountains made 

 its appearance along one of the Middle Cainozoic faults. 

 NO. I744, VOL. 67] 



In the eyes of Suess (" Antlitz," Bd. iii., pp. 312, 315, 

 and Tafel xi.), the Upper Kapoewas range forms part 

 of a great bow extending southward from the Philip- 

 pines, and the volcanoes have arisen on the faulted 

 outer side. 



The association of radiolarian cherts with diabase 

 and diabase-tuff, as described so often by the author, 

 seems almost inevitable, although the beds in Borneo 

 are of Jurassic or early Cretaceous age. Mr. J. J. H. 

 Teall has discussed this phenomenon ; and it seems 

 independent of geological age. One is reminded of 

 Anglesey, where Mr. Greenly (Quart. Journ. Geol. Soc, 

 1902, p. 433) has been led to consider the cherts as of 

 organic origin, on account of their association with 

 " pillowy diabase " — so firmly has the connection of 

 these two types of rock, however improbable at first 

 sight, become established in recent years as an article 

 of geological belief.' 



We must merely mention the interesting ascent of 

 Mount Kelam, a strangely smooth boss of pre-Creta- 

 ceous microgranitic rock, the surface of which (p. 138) 

 peels off like the layers of an onion, as in the instances 

 studied by Branner in Brazil. It soon becomes clear to 

 the reader that Central Borneo is rich in a variety 

 of mountain-forms. While Dr. Molengraaff 's land- 

 scapes will interest the geographer and the artist, other 

 illustrations are of ethnographical value. The chapter 

 on river-curves (p. 473) introduces a new term, 

 "pintas," the Dyak name for a natural short-cut 

 formed across the loop of a meandering stream. Un- 

 fortunately it has no convenient European plural, or 

 it might be of much service in geography. 



Dr. Hinde's important appendix is already known 

 to palaeontologists. The English in the translated 

 part of the volume is, as a whole, clear and carefully 

 printed. The two misprints in the title of plate lii. 

 should, however, have been avoided, but are more than 

 balanced by the action of the English binders, who 

 have curtailed the author's name on the exterior of 

 both the volumes. Dr. Molengraaff has added so much 

 to our knowledge of a difficult country, especially in 

 regard to its tectonic history, that we trust that political 

 disturbances have not removed him permanently from 

 another field of observation, where his work was 

 only just begun. Grenville A. J. Cole. 



PROCEEDINGS OF THE GERM AS 

 ZOOLOGICAL SOCIETY. 

 Verhandlungen der deutschen zoologischen Gesell- 

 schaft, xii. Versammlung, Giessen, 1902. Pp. 

 iv + 221. (Leipzig: Engelmann, 1902.) 



THE German Zoological Society consists of about 

 240 experts, who meet in variable numbers for 

 two or three days annually in some happily chosen 

 hospitable spot, where they hold high discourse. There 

 were only about sixty members present at last 

 summer's (twelfth) meeting in Giessen, but the Society, 

 if not large in numbers, is strong in quality. It is 

 not pecuniarily rich, for it has backed out of more 

 than an honorary responsibility with regard to one of 

 its offspring— an expensive child—" Das Tierreich," 

 which the Berlin Academy of Science will henceforth 

 solely foster, but it is rich in enthusiasm, as we infer 



