The geological relationship between Mt Kinabalu and neighbouring regions

Abstract

For this meeting an account has been requested of the relationship between Mt Kinabalu and the geology of the neighbouring regions in as far as this is likely to have influenced the fauna and flora. This involves a consideration of two of the most interesting and striking features in South-East Asia. The first is Mt Kinabalu itself; at 13455 ft. it is the highest and most spectacular peak in the Malayan Archipelago. Unlike many other facts this is not only true scientifically, but can readily be seen to be so, for approaching North Borneo on either its east or west coast one of the first sights, and a most impressive one, is of the mountain mass dominating the sky-line and often even rising above the scattered white cumulus clouds. The second feature is the Sunda Shelf, one of the most extensive and best defined shelf areas in the world. The identification of this shelf area in the first half of the last century marks it as one of the earliest regional geological features to be recognized in South-East Asia; we will examine it in the light of recent investigations and in particular the findings of palaeontological and age determination work. Figure 26 shows the main features of their regional setting. The two features mentioned above appear to be of primary importance in influencing the regional fauna and flora. The influence of Mt Kinabalu will be referred to first, but only briefly as the mountain is being described by Mr Collenette and Mr Askew; the Sunda Shelf will then be considered more fully. Mt Kinabalu influences the fauna and flora by a number of factors of which the more important are its altitude, its composition and its relationship to other highland areas now separated from it by lowlands and seas. Of these the last two are geologically significant. The composition of the rock forming the mountain is varied: the main peaks are granodiorite, but within the massif there are two large areas of older ultra-basic rock and also a highland area (Pinosuk Plateau) formed in more recent times from rock debris. The rock composition is a factor in determining the soils which in turn affect the flora, but it is the geological relationship of the mountain to the surrounding islands and mainland area which is of particular regional interest. An outline of the regional geology enables this to be appreciated. In the last fifteen years there has been a substantial increase in the knowledge of the geology of British Borneo, Malaya and southern Thailand, but with some exceptions full descriptions of the findings have yet to be published; thus attempts to correlate regionally the new data with older results and ideas are scanty. An attempt to do this is made below and the following features are outlined: ( a ) the regional geology, ( b ) the Sunda Shelf, and ( c ) the geological relationship of Kinabalu to the surrounding area.