﻿1851.] 



LOGAN — GEOLOGY OF SINGAPORE. 



317 



of laterite-rock in Government Hill (35), Mount Sophia (48), and 

 Mount Seligi (47), where the clay is intercalated amongst the sand- 

 stone, which latter is highly indurated. 



On the Batam side of the Strait the sandstone is found from Sunge 

 Ledi in Batam Bay to Bulan Bay, and at some places contains iron- 

 rock. The east side of Bulan Bay and the whole N.E. promontory 

 of Batam with Pulo Nongsa is granite, which differs from that of 

 Singapore in colour and in heing larger-grained. 



3rd zone. — On the east coast of Batam, in contact with the granite, 

 are found iron-rock and clay, and, in the granite, iron-dykes contain- 

 ing casts of shells. The third zone includes the island of Pulo Ubin, 

 consisting of various forms of granite and syenite (often approaching 

 to and sometimes passing into greenstone) and remarkable for its 

 tabular and concentrically laminar structure and its extraordinary 

 grooves, resulting from the action of decomposition on its rocks ; — 

 the eastern promontory of Singapore has a similar composition ; Pulo 

 Nanas or Kirimkin, and the mainland opposite are composed of green- 

 stone-porphyry ; the hills on the mainland at Tanjong Tanguloh of 

 decomposed plutonic rock, similar to the prevailing Singapore clay, 

 and, like it, containing ferruginous and jaspideous fragments ; the 

 small islets of P. Sijahat and P. Hantu III, consisting of foliated clay- 

 stone and chert, varying from subcrystalline to highly crystalline, 

 generally very hornblendic, and traversed in P. Sijahat by a dyke of 

 greenstone-porphyry ; Pulo Tikong Besar and Pulo Tikong Kichi 

 are chiefly sandstone, highly indurated, and with iron-rock ; in the 

 sea off the S.W. point of Tikong Besar rocks of granite occur, called 

 Batu Kapala Tua* ; Marbukit (Johdr Hill) is composed of clays 

 and conglomerates, indurated, passing into crystalline chert, &c, and 

 of quartz and iron-rock ; — the coast of Bintang, from Tanjong Ka- 

 lumpong to Tanjong Subong, is probably granitic. 



4th zone. — In the fourth zone we find on the east bank of the Johor 

 River, at Johor Lamaf, granite ; to the south of it, grit and con- 

 glomerate, from Tanjong Iladong to Tana Runto (in the conglomerate 

 of which fragments, partially decomposed, of chloritic granite, some 

 very little rounded, are found), and probably as far as Tanjong Boe ; 

 in Gunong Ban and the lower hills behind it on the S. Karang, green- 

 stone, varying from compact to granular, the latter approaching the 

 fine-grained granites of Pulo Ubin ; along the south coast of the S.E. 

 promontory of the Peninsula at Tanjong Tiram greenstone-porphyry ; 

 at T. Telumpong, granite ; at Tanjong and Pulo Rumnia, shales, 

 further to the E. passing into subcrystalline rocks ; at T. Penyusoh 

 (Point Romania), Peak Rock, South Island, and Pedro Branco (not 

 included in the map), syenite ; North Rock, shale ; along the east 

 coast, facing the China Sea, at Tanjong Pungai and Tanjong Kinawar, 

 talcose sandstone and shale, sometimes semi-crystallized, with abun- 

 dance of iron-rock in large rounded shining blocks, and quartz J ; — 



* J. T. Thomson, Esq. 



f This Bugis town is further north than the map extends. 

 X See my " Notices of the Geology of the East Coast of Johore." Journ. Ind. 

 Arch. vol. ii. p. 625. 



