Our knowledge of the stratigraphy of the young-paleozoic and particularly of the post-paleozoic rocks of the Netherlands East Indies is fairly extensive. Very little is known about the older paleozoic. Older paleozoic sediments are mentioned on various occasions, but the determination of the age of the rocks is mostly based on an assumption, that is made more ore less probable by the stratigraphic relation to younger fossil-bearing rocks, and not by the actual fossils, which are typical for that formation. The metamorphic rocks, which are exposed over large areas, were considered by early investigators as to belong to a very early epoch of geologic history: mostly pre-cambrian. A few fossils proved the presence of younger metamorphic rocks since. Part of these metamorphic rocks are of paleozoic age.