NA TURE 



49 



THURSDAY, MAY i6, i{ 



BORNEO. 



Borneo : Etitdeckungsreisen iind Untersuchungen ; Gegen- 

 wiir/iger Stand der Geologischen Kenntnisse ; Ver- 

 breitung der Ntitzbaren Mineralien. Von Dr. Theodor 

 Posewitz. (Berlin: Friedlander, 1889.) 



IN the work before us, Dr. Theodor Posewitz, of the 

 Hungarian Geological Institute, gives the results of 

 his three years' personal explorations in the Island of 

 Borneo, with which he has incorporated the more im- 

 portant observations which are recorded in the literature 

 of the subject. The larger portion of this literature being 

 in Dutch, it is, as a whole, not very widely known ; 

 it is, accordingly, a matter of considerable importance to 

 have it here summarized and critically examined by so 

 competent an authority. 



The three parts into which the volume is divided are : 

 (i) Political and Historical ; (2) Geological ; and (3) 

 Economic Mineralogy. Each of these parts is further 

 subdivided into a number of clearly-defined sections, so 

 that there is no difficulty experienced in at once master- 

 ing the range and contents of the work, which are further 

 indicated by means of four excellent maps, showing re- 

 spectively, (i) the routes of travellers, (2) the political 

 divisions, (3) the geological structure, and (4) the 

 distribution of useful minerals. 



We are told, in Part I., that two-thirds of the island 

 belong to the Dutch, but that the States on the north 

 coast are more or less under British influence. 



The history of exploration, as conducted by the Dutch, 

 is treated separately from that which originated in con- 

 nection with British colonial enterprise. During the 

 last century, only one extensive journey was undertaken 

 in Dutch Borneo, and scientific exploration was then 

 altogether prohibited. 



The genuine exploration of the country did not begin 

 till 1820-30, when a Natural History Commission was 

 established in Batavia, and its members undertook to 

 investigate artd describe various islands. Among others, 

 Horner, G. Miiller, Dr. Schwaner, and Von Gafifron 

 devoted themselves to Borneo, and to the two last we 

 owe our knowledge of South Borneo. Between the years 

 1850-60, systematic explorations for useful minerals were 

 carried on by Dutch engineers in South-West Borneo, 

 and these explorations have been recently resumed, after 

 an interval of twenty years. 



To Alexander Dalrymple, who travelled in 1769, we 

 are indebted for our first knowledge of North Borneo ; 

 other early travellers were Burns, Hugh Low, and 

 Spenser St. John, who visited Sarawak, Brunei, and the 

 north-east coast, and ascended the Kina Balu Moun- 

 tains. Among later travellers, Crocker and H. Everett 

 merit special notice ; as also do the courageous pioneers 

 in the British Ntsrth Borneo Company's territory — Dobree, 

 Peltzer, Wetti, Von Donop, Pryer, and F. Hatton. 



With regard to the geological and physical structure, 



which are dealt with in Part II., we are told that there 



is no uninterrupted central mountain chain in Borneo, 



though such is represented on most maps. Isolated 



Vol. XL. — No. 1020. 



mountains occur at intervals, surmounting table-lands 

 which extend in a north-east to south-west direction ; but 

 it is not yet decided whether a regular chain exists in 

 any part of the interior. The Kina Balu Mountains, 

 which have a maximum elevation of 13,698 feet, are, so 

 far as is at present known, the highest in the island ; they 

 are situated in the territory of the British North Borneo 

 Company. 



The largest rivers — the Barito, Kapuas, Redjang, and 

 Mahakkam — rise in the centre of the island. 



The geological structure is remarkably free from com- 

 plexity. The isolated mountains are of slate or schist 

 penetrated by granite and diorite — conditions, it may be 

 remarked, which are in many countries accompanied by 

 the occurrence of mineral veins ; this also seems to be 

 the case in Borneo. 



Succeeding these are rocks of Devonian age, in 

 which auriferous veins occur. Till quite recently no 

 formations had been recognized between them and the 

 Tertiary deposits which have long been known, but Car- 

 boniferous strata (mountain limestone), which it is be- 

 lieved occur throughout a large area in Northern Borneo, 

 have within the last few years been recognized, and 

 Cretaceous rocks have been discovered in a single 

 locality in West Borneo. 



Tertiary formations belonging to several subdivisions 

 are distributed over considerable areas ; they form the 

 plateaus through and above which the mountain chains 

 rise. The older Tertiary strata were first studied by 

 Verbeek and Pengaron in South Borneo. They are 

 divisible into sandstone, marl, and limestone groups. 

 The majority of the coral deposits occur in the sand- 

 stone,, and the limestones consist mainly of wide-spread- 

 ing coral reefs. These older Tertiary strata are often 

 much disturbed and • broken by intrusive masses of 

 andesite. Oligocene strata are only known in Eaist 

 Borneo, where they include extensive deposits of coal. 



The diluvium of our author is of considerable economic 

 importance. It spreads over wide undulating tracts sur- 

 rounding the Tertiary hills. It includes the principal 

 sources of the gold and diamonds which, together with 

 coal, constitute the most valuable mineral resources of 

 the island. From the diluvium to the alluvium which is 

 in process of formation at present, there is a gradual 

 transition. 



There are no evidences of any post-Tertiary volcanic 

 energy in Borneo. The Kina Balu Mountains, at one 

 time thought to be volcanic, are now known to consist of 

 ancient eruptive masses. Earthquakes occur, but rarely, 

 and so far as is known they originate in neighbouring 

 islands. 



In West Borneo a deposit which appears to be identical 

 with one form of Indian laterite, is described as resulting 

 from the weathering of the rocks. A similar laterite 

 occurs near Singapore. 



Taking a general survey of the probable geological 

 history of Borneo, it appears that, up to the beginning of 

 the Tertiary period, what now forms one united island 

 consisted of an archipelago like that between Singapore 

 and Banka. After the deposit of the Tertiary strata 

 there followed a period when the island had the form of 

 the Celebes. A tradition among the natives, that the sea 

 formerly reached to the foot of the mountains, is referred 



D 



