332 The American Geoloijiaf. Novomber, ife97 
189G. This work, begun in 1881 under Verbeek, has been prosecuted, 
with intarrujjtions, till 189(5, including the time required for publication, 
and in the meantime several other geologists have; assisted, and several 
other important enterprises have been completed, the most important 
being, perhaps, the exploitation of the volcano Krakatoa after the mem- 
orable eruption of August, 1883. 
The geologic range of the rocks described, belonging to Java, is from 
certain ancient schists, seen at the islands Karimoun diawa, whope age 
is undetermined but earlier than the Carboniferous, to tiie Tertiary and 
the modern. There is, however, a great interval from the oldest schists 
to the Cretaceous, unrepresented by any geologic formation. The fol- 
lowing table expresses the percentage of superficies occupied by the va- 
rious rocks. 
per cent. 
The oldest schists (only at Karimoun diawa). . 0.046 | 
Cretaceous, including eruptive rocks (gabbro, ] 
diabase, quartzose jjorphyry te) . 125 | i i c- 
Eocene, including eruptives i 0.232 f . ' ' 
Oligocene, including eruptives 0.004 | 
The oldest audesyte and basalt 0. 723 J 
Neo-Tertiary Mi 14 . 419 ] 
Neo-Tertiary Mz 13.526 !>37 .752 
Neo-Tertiary My 9. 807 J 
Leucitic and phonolitic rocks 1.590 \ nr~ nt)-. 
Volcanoes 26.031 ^ "''^^^ 
Quaternary 21 .024 / oo ^7(1 
Modern 12.44G \ '^ ^'^'^^ 
100.000 
If all the superficies older than the Mi(x;ene, including the eruptive 
rocks at the base of the Miocene, be grouped together, they constitute 
therefore, as remarked by the authors, only one per cent, of the surface 
of Java: the Miocene forms .38 per cent.; the volcanic rocks 28 per cent., 
and the post-Tertiary sediments 3.3 per cent. 
The oldest schist, which is supposed to be of the same age as that 
which also appears in Sumatra and Borneo, is considered to be either 
Devonian or Silurian. 
The Cretaceous beds are referred to the Senomian. l)ut not with pos- 
itiveness, there being a scarcity of fossils. 
The sediments of the Tertiary and their volcanoes occupy the chief 
place in the descriptive portions of this work. 
One hundred and thirty one volcanoes are listed by name, ranging 
from an altitude of .3676 meti-es to 63 metres, Krakatoa being 822 metres. 
Of these volcanoes 29 are said to be active, although any one of them 
is liable to resume activity. Tlie highest voleaiioes are, in general, the 
most active, Krakatoa being however an exception. It had, still, been 
in repose for 203 years before the eruption of 1883. A moderate estimate 
of the amount of matter ejected at that time makes at least 18 cubic- 
kilometres. Compared with this the volumeof rock ejected by the other 
mtich larger volcanoes of Java must have been at least ten times thif? 
volume, and probably more than fifty times, in the form of lava streams 
and sheets and volcanic ash and breccia. 
