The Upper "T.f" Letter Stage is now widely accepted to be the later part of the Middle Miocene and the Late Miocene (c. 12 to 5 mybp). This convention follows Adams (1970), although the mass extinction of larger forams at about 12 mybp was the event that was first proposed as the top of Tf. What we now call Upper Tf was originally "T.g" (Leupold & van der Vlerk 1931), and likewise the T.f 1 to 3 subdivisions have ambiguous meanings to different generations.
- Limestone from Margamukti N. C. Java (564 KB). This site was first descibed by Hetzel (1935) in the mapping quadrangle reports for Sheet 54, Majengang. The sediments here were mapped as the "Lawak Beds". These consisted of flaggy (up to 20 cm thick) grey-yellow foraminiferal limestone, between brittle mudstone with minor volcaniclastic (andesite) sandstone. Tan Sin Hok determined the following foraminifera from the limestone: Cycloclypeus indopacificus Tan (with very variable sculpture), Radiocycloclypeus sp., Trybliolepidina radiata Martin, Trybliolepidina stellata (Scheffen), Trybliolepidina sp. 1. aff. rutteni van der VIerk. He dated the sample as Middle Miocene as Cycloclypeus most commonly has 6 nepionic chambers (range 4 to 8). Recent work on nannofossils re-dates this unit as the lower to mid Late Miocene (lower part of Zone NN11, on the presence of Discoaster quinqueramus, D. berggrenii and Helicosphaera orientalis.
The sample shown here is from the river Cicabe, downstream from the village of Margamukti. Hetzel reported an oil seep / rock smelling of oil at this locality, from blue-gray, slightly marly claystone or tuffaceous claystone.
- Limestone from Penyaten Beds N. C. Java (600 KB). Above the Lutut area. The specimens of Lepidocyclina are of the Trybliolepidine form.
