Triassic beds with Halobia and Monotis are well-developed in Rotti and appear also to occur in Timor.
Fragments of Jurassic rock have been found amongst the volcanic material on the island of Rotti, but they have not yet been discovered in situ.
Dutch Timor gives its name to a residency comprising, besides its own territory, the small adjacent islands, Rotti, Peman, &c., the Savu islands, Sumba or Sandalwood island, the Solor and Allor group of islands, and the eastern half of Flores, all lying between 8° 5' and 11° 5' S.
It is divided into four administrative districts - Timor, Rotti and Savu, Larantuka (eastern Flores) and Sumba.
Rothpletz, Die Perm-, Trias-, and Jura-Formation auf Timor and Rotti im indischen Archipel, Palaeontographica (1892) pp. 57106.