248 THE GEOLOGY OF THE MALAY PENINSULA. 
The chert series of. South Selangor, Negri Sembilan and’ 
Pahang is overlain by grits, quartzites, and shales, the lower portion 
of which includes beds of conglomerate, in which the pebbles consist 
in the main of quartz, quartzite, radiolarian chert, and rocks of the 
Pahang Volcanic series. It is probable that this quartzite and 
shale series is separated by a considerable unconformity from the 
underlying cherts and quartzites, and that strong folding move- 
ments. which affected the latter, had ceased when the shallow -water 
conditions of the Rhaetic and Jurassic periods had set in. 
In Yunnan and parts of Indo-China there were land conditions 
from the upper Triassic to the present day, but the Shan sea basin, 
described below, extended into Yunnan, so some Rhaetic beds were 
formed resembling the Napeng beds of the Shan States. The 
Napeng beds are fossiliferous clays, sometimes calcareous, laid down 
on the irregular surface of the Plateau Limestone. The fossils 
they contain are sometimes ill-developed, owing to the fact that 
they hved in cups in the limestone not in free communication 
g 
with the open sea, while in other places the fossils are well grown. 
The number of new species shows that great changes in the “distri- 
bution of sea and land had taken place between the deposition 
of the Permo-Carboniferous and the Napeng beds, and the basin 
of the Shan sea was isolated from the main ocean. It extended 
into Yunnan, as mentioned above, and into the Malay Peninsula, 
where characteristic Rhaetic fossils have been found in three or 
four places east of tle Main Range, possibly also in Singapore 
Island, and certainly on the west ‘coast of Sumatra. Im French 
Indo-China the Rhaetic period was represented by shallow-water 
beds also, including the coal beds of Tien Yen Lang Then. 
Jurassic. 
As already mentioned, there is an extensive series of shallow- 
water and, estuarine shales and quartzites, of Jurassic age, in the 
Malay Peninsula. The shales have usually been converted into 
phyllites by the earth-movements which took place at the time of 
the intrusion of the Mesozoic granite masses, and they show sharp 
folds and faults. The shales are locally carbonaceous, and certain 
intrusions are known, consisting of about forty or fifty per cent 
carbon and the remainder siliceous material, which probably re- 
present coal seams which were altered by the granite. 
In Burma, the Mergui series of slates, argillites, clay-schists, 
and silicified tufts, with subordinate quartzites and conglomerates, 
have been regarded as corresponding with the shallow- water Juras- 
sic series of quartzites and shales further south in the Peninsula. 
However, as the Officiating Director of the Geological Survey of 
India in his General Report for 1920 (page 26), describes the 
series as underlying the Moulmein Limestone formation, it 
now appears that the rocks are of Carboniferous or pre- 
Carboniferous age, and that they correspond with the similar series 
Jour. Straits Branch 
