The book is a comprehensive compilation of all aspects of the geology of Northwest Borneo (Sarawak, Brunei and Sabah) and the contiguous South China and Sulu Seas. The sedimentary formations are described, their palaeontology tabulated and ages discussed. Stratigraphic charts illustrate their relationships across the whole region. Detailed geological maps of selected areas are accompanied by cross sections based on outcrop patterns and drilling and seismic data offshore. Palaeocurrent maps are presented and the palaeogeography for different ages described and sedimentary provenance discussed. Descriptions of the ophiolite sequences, volcanic and plutonic rocks are accompanied by tables of selected chemical analyses and geochemical plots and their tectonic significance discussed. All radiometric data are tabulated and discussed. Regional structures and the predominantly Tertiary tectonics are described. In Sarawak, the mountains are constructed of Upper Cretaceous to Lower Eocene greenschist facies shaly turbiditic Rajang Group, uplifted before the end of the Eocene. In Sabah, the Western Cordillera is constructed of Eocene to Lower Miocene sandy turbidite uplifted in the Late Miocene and Pliocene. Miocene intrusion of Mount Kinabalu and uplift of the Cordillera is related to collision at the Northwest Borneo Trough. Gold, antimony, mercury and copper deposits are described and the tectonic setting of oil and gas deposits discussed. It includes correlation tables, descriptions and ages of all major sedimentary formations of Sarawak, Brunei and Sabah. It covers the petrology, geochemistry and ages of all volcanic and plutonic formations of North West Borneo and their tectonic significance. It also contains the economic geology including the geological setting of offshore oil and gas deposits.