ch mention has already been made, there occurs Lake Luar,
and there are several lake expanses of a similar character in the basins
of the Barito and Kutei rivers. The only really fine natural harbour in
the island of which any use has been made is that of Sandakan, the
principal settlement of the North Borneo Company on the north coast.

_Geology._--The geology of Borneo is very imperfectly known. The
mountain range which lies between Sarawak and the Dutch possessions,
and may be looked upon as the backbone of the island, consists chiefly
of crystalline schists, together with slates, sandstones and
limestones. All these beds are much disturbed and folded. The
sedimentary deposits were formerly believed to be Palaeozoic, but
Jurassic fossils have since been found in them, and it is probable
that several different formations are represented. Somewhat similar
rocks appear to form the axis of the range in south-east Borneo, and
possibly of the Tampatung Mountains. But the Muller range, the Madi
plateau, and the Schwaner Mountains of west Borneo, consist chiefly of
almost undisturbed sedimentary and volcanic rocks of Tertiary age. The
low-lying country between the mountain ranges is covered for the most
part by Tertiary and Quaternary deposits, but Cretaceous beds occur at
several localities. Some of the older rocks of the mountain regions
have been referred to the Devonian, but the evidence cannot be
considered conclusive. _Vertebraria_ and _Phyllotheca_, plants
characteristic of the Indian Gondwana series, have been recorded in
Sarawak; and marine forms, similar to those of the lower part of the
Australian Carboniferous system, are stated to occur in the limestone
of north Borneo. _Pseudomonotis salinaria_, a Triassic form, has been
noted from the schists of the west of Borneo. In the Kapoewas district
radiolarian cherts supposed to be of Jurassic age are met with.
Undoubted Jurassic fossils, belonging to several horizons, have been
described from west Borneo and Sarawak. The Cretaceous beds, which
have long been known in west Borneo, are comparatively little
disturbed. They consist for the most part of marls with _Orbitolina
concava_, and are referred to the Cenomanian. Cretaceous beds of
somewhat later date are found in the Marpapura district in south-east
Borneo. The Tertiary system includes conglomerates, sandstones,
limestones and marls, which appear to be o