30 



These rocks were not formed by the eruption of 1883 but are 

 part of the old mantle of Krakatao ') Locally the slopes are here 

 so steep that the coarse blocks of pumice-stone, which may have 

 fallen down upon them, could not remain where they fell, but rolled 

 or leapt downwards, whilst the ashes and fine pumice-grit were 

 soon washed away or slided down into the ravines or into the sea. 

 At this corner of Krakatao the sea was filled up by the eruptive 

 products and therefore in the first years after the eruption, till far 

 from the coast, rather shallow 2 ). Already in October 1883, two 

 months after eruption, the old rocks of Zwarte Hoek were found to 

 be locally bare, as appears from plate 25 in the album accompanying 

 the work on Krakatao by V e r b e e k. Therefore it is quite possible, 

 even probable, that here also, in well-sheltered localities, part of 

 the old vegetation has survived. 



Definite data about the composition of the old vegetation of 

 these rocks do not exist, as no botanist has visited them before 

 the eruption of 1883. But probably this locality will have borne the 

 same flora as the old lava-streams which Verbeek saw in the 

 no-more existing northern part of Krakatao. These lava-streams, which 

 may have been formed by the eruption of 1680 :! ) and possibly much 

 earlier, were after a lapse of at least two centuries yet unweathered, 

 and bore a very scanty vegetation. A such-like, little weathered, 

 sterile lava-stream is found at present on the eastern declivities 

 of Mount Ountur, above Tjipanas (near Caroot), and its vegetation 

 answers to the general description given by Verbeek. When in 

 )ava such sterile rocky localities are found in regions where the 

 east-monsoon, as a rule, is interrupted by repeated rains and where, 

 consequently, no extreme droughts entirely prevent the growth of 

 plants, the rocks bear, especially in their crevices, a peculiar 

 vegetation, which, for the rest, is almost restricted to vertical walls 

 of hollow roads and terraces and steep riversides. Such plants, 



1 ) Cf. Esclier in Handel. Eerste Ned--lnd. Natuurwetensch. Congres (1920), 

 p. 205; ,,lt appears from the topographical map of 1908 (jaarverslag lopogr. Dienst 

 1908) that immediately west of Zwarte Hoek a distinct valley runs in a south-eastern 

 direction. I found this valley to be the boundary between the old basaltic island and 

 the young pumice-tuffs- East of the valley basalt is found down to sea-level, west 

 of the valley pumice-tuffs down to the level of the sea". In fig- 3 of Escher's 

 paper this is distinctly marked- A very fine plate is found in (aarverslag Topogr. 

 Dienst NedIndie (Year-book of the Topographical Survey Service of the Dutch East- 

 Indies) 1920, plate XXIX. 



2 ) See the paper of Escher in Handel- Eerste Ned.-lnd. Natuurwetensch. 

 Congres (19201, p. 204 and the large map accompanying it. 



') Verbeek, Krakatau (1888), p. 5, p. 164. If in 1680 no eruption has taken 

 place these lava-streams must have flown out before that year- 



