238 THE GEOLOGY OF THE MALAY PENINSULA. 
known in considerable detail. For example, no explanation has 
vet been given of the recently extinct volcanoes which occur in a 
belt of Tertiary beds in Burma, between the Irrawaddy and the 
Shan States. If they were situated near the great fault-plane 
which passes ‘from north to south many miles to the east, their 
presence could easily be explaimed, but their occurrence in Tertiary 
beds, so far from this great fault, is a mystery. 
Earth Movements. 
The geographical and geological features of the area were 
established as the result of “foliding-movements of at least three 
different periods, but the earth-movement in the late Mesozoic 
period (Hereynian), and the Tertiary earth-movement, which affect- 
ed Europe, North Africa, and the other parts of -Asia, have had a 
. more widespread effect on our area than the earliest one. Folding 
movements before the Mesozoic period took place on a large scale 
only in the northern part of the area, Indo China and probably 
Yunnan, although the presence of fragments of granite in volcanic 
ashes and tuffs in Singapore, probably older than the Mesozoic 
granite of the Malay Peninsula, and the Palaeozoic granite, older 
than Permian, alluded to by Verbeek in describing the eeology of 
Amboyna, are indications that this earth-movement took place to 
some extent also in the Malay Peninsula and East Indies. 
The anfluence of the later movements is very marked in all 
of the countries under consideration, and successive parallel mount- 
ain folds, arranged roughly en échelon, can be traced through the 
area, beginning i in the northwest, near Tibet, at the eastern end of 
the huge Himalayan mountain range. ‘To these folds Suess gave 
the name “Coulisses,” and, talking of our area, he says, “Then, in 
“the Shan States of Burma, several of the coulisses which approach 
“from the north and northeast disappear beneath a karst-lke 
“plateau of Palaeozoic limestone, which is folded and! owes its 
“tabular form to denudation. Fresh coulisses make their appear- 
“ance in the south and form the Malay Peninsula.......“In this 
“Way the mighty swell of the Altaides in Thibet subsides and is 
“dispersed. The whole continent becomes lower. Many coulisses 
"disappear. Only a few long branches are continued ‘on the east 
‘onto the cordillera of Annam; on the west, always giving rise to 
“fresh coulisses, through the Malay Peninsula, and still “further, 
“to Java and bey ond.” 
The most prominent coulisse in the western part of the area 
is the Naga-Arakan-Andaman-Nicobar-Barissan fold, with its axis 
extending from Upper Burma in the northwest, running south 
through the Andaman Islands, and the Nicobar Islands, and turn- 
ing east through Sumatra and Java. Another important couliisse 
ean be traced as the Main Range in the Malay Peninsula, through 
Singkep and Banka, and the result of the earth- movement which 
caused this particular fold was the intrusion of the Mesozoic granite, 
accompanied by the mineralisation from which originated the 
Jour. Straits Branch 
